JP4476915B2 - Digital demodulator, control method therefor, program for digital demodulator, recording medium storing program for digital demodulator, and digital receiver - Google Patents

Description

  The present invention relates to a digital demodulator that demodulates a modulated signal subjected to interleave processing, a control method thereof, a program for a digital demodulator, a recording medium that records a program for a digital demodulator, and a digital receiver.

  A digital demodulator that demodulates a modulation signal includes a tuner that performs channel selection processing on the modulation signal and a demodulator that performs demodulation processing. And the control part of a digital demodulator performs various control which changes the operation parameter with respect to each circuit component which comprises a tuner and a demodulator.

  However, an error may occur in a signal handled by the digital demodulator by the control as described above. The digital demodulator disclosed in Patent Document 1 has a configuration in which the influence of power control is less likely to affect the received signal by turning the power on or off during the guard interval.

JP 2001-251275 A

  However, the control by the digital demodulator of Patent Document 1 can be performed only during the guard interval. Further, even when control is performed during the guard interval period, such control may affect the signal beyond the guard interval period. Then, an error that has occurred in the signal beyond the guard interval period remains in the received signal, and there may arise a problem that accurate information cannot be acquired when acquiring information such as images and sounds from the demodulated signal. .

  SUMMARY OF THE INVENTION An object of the present invention is to provide a digital demodulator capable of obtaining more accurate information from a demodulated signal, a control method thereof, and a digital demodulation It is an object to provide a recording medium on which a program for a device, a program for a digital demodulation device are recorded, and a digital receiving device.

Means for Solving the Problems and Effects of the Invention

  A digital demodulator according to the present invention includes a plurality of circuit components that constitute a tuner that performs channel selection processing on a reception signal that has been subjected to interleave processing, and a demodulator that performs demodulation processing on the reception signal from the tuner. ing. The digital demodulator also includes a deinterleave unit that performs a deinterleave process on the received signal from the tuner that has been subjected to an interleave process, and a reception that the deinterleave unit performs a deinterleave process. Error correction means for correcting an error included in the signal.

  The digital demodulator is provided with the following means as control means for the tuner or demodulator. First, an operation parameter changing unit that changes at least one operation parameter of the plurality of circuit components, and a first circuit component in which the operation parameter is changed by the operation parameter changing unit among the plurality of circuit components. And a first change determining means for determining a change amount of the operating parameter relating to the first circuit component, and a second circuit component whose operating parameter is changed by the operating parameter changing means among the plurality of circuit components. The first change determination means determines the operation parameter of the first circuit component determined by the first change determination means, as compared to the case where the operation parameter related to the second circuit component is not changed. The error that is included in the received signal when the operating parameter changing means changes by the changed amount As the amount of errors is positive means included in the received signal after the correction is reduced, it is a second change determining means for determining the change amount of the operating parameters according to the second circuit component.

  Further, as means for determining whether or not an error that is expected to occur can be corrected, the change determined by the first change determination means is the operation parameter of the first circuit component determined by the first change determination means. Error estimating means for estimating the amount of virtual error that will occur in the received signal when the operation parameter changing means changes by an amount, and the operation of the first circuit component determined by the first change determining means Whether or not the error correction means can correct an error that is included in the received signal by changing the parameter by the change amount determined by the first change determination means by the operation parameter change means. First correctability determination means for making a determination based on the amount of the virtual error estimated by the means is provided.

  Further, as a means for performing control based on the determination of whether or not error correction is possible, the first correction possibility determination means determines that the error correction means cannot correct an error included in the received signal. In this case, the operation parameters of the first and second circuit components determined by the first and second change determining means are changed by the change amounts determined by the first and second change determining means, respectively. In addition, parameter change control means for controlling the operation parameter change means is provided.

  Further, the control method of the digital demodulator according to the present invention includes a plurality of circuits constituting a tuner that performs channel selection processing on a reception signal that has been subjected to interleaving processing, and a demodulator that performs demodulation processing on the reception signal from the tuner. Parts, deinterleaving means for performing deinterleaving processing on the received signal from the tuner subjected to interleaving processing, and error correcting means for correcting an error included in the received signal subjected to deinterleaving processing by the deinterleaving means; A control method for a digital demodulator comprising an operation parameter changing means for changing an operation parameter of at least any one of the plurality of circuit components, wherein the operation parameter changing means among the plurality of circuit components The first circuit component whose operation parameter is changed by the first circuit component and the first circuit component A first change determination step for determining a change amount of the operation parameter; a second circuit component whose operation parameter is changed by the operation parameter changing means among the plurality of circuit components; and the second circuit The operation parameter of the first circuit component determined in the first change determination step is equal to the change amount determined in the first change determination step than the case where the operation parameter related to the component is not changed. The operation parameter related to the second circuit component is reduced so that the amount of error included in the received signal after the error correcting unit corrects the error included in the received signal by the changing unit being changed. A second change determining step for determining a change amount of the first circuit component, and an operation parameter of the first circuit component determined in the first change determining step. An error estimation step for estimating the amount of virtual error that will occur in the received signal when the operating parameter change means changes the change amount by the change amount determined in the first change determination step; The operation parameter changing means changes the operation parameter of the first circuit component determined in the change determination step by the change amount determined in the first change determination step, and is included in the received signal. A first correctability determination step for determining whether the error correction means can correct an error based on the amount of the virtual error estimated in the error estimation step; and an error to be included in the received signal Is determined in the first and second change determination steps when it is determined in the first correction possibility determination step that the error correction means cannot correct the error. Parameter change control for controlling the operation parameter changing means so that the operation parameters of the first and second circuit components are changed by the change amounts determined in the first and second change determination steps, respectively. And steps.

  Further, the program for a digital demodulator according to the present invention includes a plurality of circuit components that constitute a tuner that performs channel selection processing on a reception signal that has been subjected to interleave processing, and a demodulator that performs demodulation processing on the reception signal from the tuner. A program for use in a digital demodulator comprising: a deinterleaving unit that performs a deinterleaving process on a received signal from the tuner that has been subjected to an interleaving process; and the deinterleaving unit that has performed the deinterleaving process. An error correction unit that corrects an error included in the received signal, an operation parameter change unit that changes an operation parameter of at least one of the plurality of circuit components, and an operation parameter change unit that operates among the plurality of circuit components. First circuit component whose parameter is changed and the first circuit A first change determining means for determining a change amount of an operation parameter related to a product; a second circuit component whose operation parameter is changed by the operation parameter changing means among the plurality of circuit components; The operation parameter of the first circuit component determined by the first change determination unit is equal to the change amount determined by the first change determination unit than when the operation parameter related to the circuit component is not changed. The operation parameter related to the second circuit component is reduced so that the amount of error included in the received signal after the error correcting unit corrects the error included in the received signal by the changing unit being changed. Second change determining means for determining a change amount of the first circuit component, and operating parameters of the first circuit component determined by the first change determining means for the first change. Error estimating means for estimating the amount of virtual error that will occur in the received signal when the operating parameter changing means changes by the change amount determined by the determining means, and the first change determining means determined by the first change determining means The virtual parameter estimated by the error estimation unit is an error that is included in the received signal when the operation parameter change unit changes the operation parameter of the circuit component by the change amount determined by the first change determination unit. First correction enable / disable determining means for determining whether or not the error correction means can correct based on the amount of errors, and the first error correction means if the error correction means cannot correct the error included in the received signal. When the correction enable / disable determining means determines, the operating parameters of the first and second circuit components determined by the first and second change determining means are the first and second circuit components. The digital demodulator is caused to function as parameter change control means for controlling the operation parameter change means so that the change amount determined by the second change determination means is changed.

  According to the digital demodulating device, the control method thereof, and the program for the digital demodulating device of the present invention, the errors remaining after error correction by the error correcting means among the errors caused by the change of the operating parameters related to the first circuit component are Reduced by changing operating parameters associated with circuit components. For this reason, it is possible to obtain more accurate information from the received signal even when an error that is included in the received signal when the operation parameter related to the first circuit component is changed is not correctable. . In this specification, “changing the operation parameter of the circuit component” means changing the parameter such as the power consumption of the circuit component, but controlling the power consumption of the circuit component itself to change. Is equivalent to

  In the digital demodulator according to the present invention, the first correction enable / disable judging means derives a threshold value of an amount of error that is included in the received signal due to an operation parameter change in the first circuit component. 1 threshold deriving means, and when the error amount estimated by the error estimating means is less than or equal to the threshold derived by the threshold deriving means, the first change determining means determines the When the error correction unit can correct an error included in the received signal by changing the operation parameter of the first circuit component by the change amount determined by the first change determination unit by the operation parameter change unit. It is preferable to judge. According to the above configuration, it is possible to easily determine whether or not the error included in the received signal can be corrected by comparing with the threshold value.

  In the digital demodulator according to the present invention, the first threshold value derivation means is built in the tuner, and at least one of a modulation method and a coding rate in a received signal is transmitted from the demodulator to the tuner. It is preferable that the first threshold deriving unit derives the threshold based on at least one of a modulation scheme and a coding rate in the received signal. According to the above configuration, information necessary for deriving the threshold can be extracted from information acquired when the demodulator performs demodulation processing on the received signal. Therefore, an appropriate threshold value is derived according to the method adopted for the received signal.

  In the digital demodulator according to the present invention, the second change determining means determines the operation parameter of the first circuit component determined by the first change determining means. Based on the amount of the virtual error estimated by the error estimation means so that the error that is included in the received signal by the change of the operation parameter by the change amount can be corrected by the error correction means. Preferably, the second circuit component and the change amount of the operation parameter related to the second circuit component are determined.

  In the control method of the digital demodulator according to the present invention, in the second change determination step, the operation parameter of the first circuit component determined in the first change determination step is used as the first change determination. The virtual parameter estimated in the error estimation step is such that an error that is included in the received signal by the operation parameter changing means being changed by the change amount determined in the step can be corrected by the error correcting means. It is preferable to determine a change amount of the operation parameter related to the second circuit component and the second circuit component based on the amount of error.

  According to the above configuration, even if it is determined that an error that is included in the received signal due to a change in the operation parameter related to the first circuit component is uncorrectable, the operation is performed so that such an error can be corrected. Since the second circuit component related to the parameter change and the change amount related to the change of the operation parameter are determined, the error included in the received signal is corrected by the error correction means. As a result, accurate information is obtained from the received signal.

  In the digital demodulator of the present invention, the first and second change determining means determine the operating parameters of the first and second circuit components determined by the first and second change determining means. Whether or not the error correction means can correct an error that is included in the received signal by changing the operation parameter change means by the change amount based on the virtual error amount estimated by the error estimation means. And a second correctability determination means for determining whether the error correction means cannot correct an error to be included in the received signal, and is included in the received signal. The first and second change determining means determine the second correction determining means when the second correction determination means determines that the error correcting means can correct the error to be corrected. Preferably, the parameter change control means controls the operation parameter changing means so that the operation parameters of the second circuit component are changed by the change amounts determined by the first and second change determining means, respectively. .

  In the control method for the digital demodulator according to the present invention, the first and second change determinations may be performed on the operation parameters of the first and second circuit components determined in the first and second change determination steps. An error that is included in the received signal when the operation parameter changing unit changes by the change amount determined in the step, based on the virtual error amount estimated in the error estimating step, Further comprising a second correction possibility determination step for determining whether or not the error correction means cannot correct an error to be included in the received signal, and is determined in the first correction permission determination step. In addition, when it is determined in the second correction possibility determination step that the error correction means can correct an error included in the received signal, The operation parameters of the first and second circuit components determined in the first and second change determination steps are changed by the change amounts determined in the first and second change determination steps, respectively. It is preferable to control the operation parameter changing means in the parameter change control step.

  According to the above configuration, when error correction is possible by changing the operating parameter related to the second circuit component, the operating parameter in the first and second circuit components is changed. As a result, error correction is possible even if the operating parameters of the first circuit component are changed.

  In the digital demodulator according to the present invention, the second correction possibility determination means sets a threshold value of an amount of error that is included in the received signal due to an operation parameter change in the first and second circuit components. Second threshold deriving means for deriving and the change determined by the first and second change determining means for the operating parameters of the first and second circuit components determined by the first and second change determining means A total error amount deriving unit for deriving an error amount to be included in the received signal by the operation parameter changing unit by an amount based on the virtual error amount estimated by the error estimating unit; And when the error amount derived by the total error amount deriving unit is equal to or less than the threshold derived by the second threshold deriving unit, the first and second change determining units are An error that is included in the received signal when the operation parameter changing unit changes the determined operation parameter of the first and second circuit components by the change amount determined by the first and second change determining unit. Is preferably determined by the error correction means. According to the above configuration, it is possible to easily determine whether or not the error included in the received signal can be corrected by comparing with the threshold value.

  In the digital demodulator of the present invention, the second threshold deriving means is built in the tuner, and at least one of a modulation method and a coding rate in a received signal is transmitted from the demodulator to the tuner. And the second threshold deriving means derives the threshold based on at least one of a modulation scheme and a coding rate in the received signal. According to the above configuration, information necessary for deriving the threshold can be extracted from information acquired when the demodulator performs demodulation processing on the received signal. Therefore, an appropriate threshold value is derived according to the method adopted for the received signal.

  In the digital demodulator according to the present invention, when both the first and second correction possibility determination means determine that the error correction means cannot correct an error included in the received signal, the first correction It is preferable that the parameter change control means controls the operation parameter changing means so that the operation parameters of the first and second circuit components determined by the first and second change determining means are not changed. According to the above configuration, an error that cannot be corrected does not occur in the received signal due to the change of the operation parameter, and accurate information can be acquired from the received signal.

  In the present invention, the second change determining means determines the amount of change related to the operation parameters of the second circuit component and the second circuit component so that the error correction capability of the error correcting means is improved. It is preferable to do. According to the above configuration, the error correction capability is improved, so that more errors are corrected by the error correction means, and more accurate information can be acquired from the received signal.

  In the present invention, the second circuit component determined by the second change determining means is at least one of the plurality of circuit components constituting the tuner, and the second circuit component It is preferable that the second change determination means determines a change amount related to an operation parameter of the second circuit component so that power consumption increases. According to the above configuration, the power consumption of the circuit components constituting the tuner increases, so that the performance of the circuit components can be improved, and errors that occur in the received signal can be reduced.

  Further, in the present invention, when the first correction possibility determination means determines that the error correction means cannot correct an error included in the received signal, the second change determination means determines The first circuit component determined by the first change determination means after the operation parameter change means has changed the operation parameter of the second circuit component by the change amount determined by the second change determination means. Preferably, the operation parameter changing unit changes the operation parameter by the change amount determined by the first change determining unit. According to the above configuration, since the operation parameter related to the first circuit component is changed after the operation parameter related to the second circuit component is changed, the error amount is changed before the operation parameter related to the first circuit component is changed. The reduction effect is more likely to appear. Thereby, the influence on the received signal of an error caused by the change of the operation parameter related to the first circuit component can be further reduced.

  In the digital demodulator according to the present invention, the deinterleave processing performed on the received signal by the deinterleave means is time deinterleave processing, and the operation parameter of the second circuit component determined by the second change determining means The first circuit determined by the first change determining means after the time interleave length has elapsed after the operation parameter changing means has changed by the change amount determined by the second change determining means. Preferably, the operation parameter changing unit changes the operation parameter of the component by the amount of change determined by the first change determining unit.

  In the method for controlling a digital demodulator according to the present invention, the deinterleaving process performed on the received signal by the deinterleaving means is a time deinterleaving process, and the second circuit determined in the second change determining step is used. Determined in the first change determination step after a time interleave length has elapsed after the operation parameter change means has changed the operation parameter of the component by the change amount determined in the second change determination step. Preferably, the operation parameter changing means changes the operation parameter of the first circuit component by the change amount determined in the first change determination step.

  According to the above configuration, after the effect of reducing the error amount due to the change of the operation parameter related to the second circuit component is sufficiently exhibited, the operation parameter related to the first circuit component is changed. Thereby, the influence on the received signal of an error caused by the change of the operation parameter related to the first circuit component can be further reduced.

  In the digital demodulator according to the present invention, the operation parameter changing unit may change the operation parameter of the second circuit component determined by the second change determining unit by the amount of change determined by the second change determining unit. From the time of change to the time when the operation parameter changing means changes the operation parameter of the first circuit component determined by the first change determining means by the amount of change determined by the first change determining means. The change amount determined by the second change determination unit after the change unit does not change the operation parameter of the second circuit component and the operation parameter change unit changes the operation parameter of the first circuit component. The operation parameter changing means can return the operation parameter of the second circuit component from the operation parameter after the change by the operation parameter to the operation parameter before the change. It is preferred. According to the above configuration, when the power consumption temporarily increases due to the change of the operation parameter related to the second circuit component, the operation parameter related to the second circuit component is returned to the state before the change. Therefore, power consumption can be kept low.

  In the digital demodulator according to the present invention, the deinterleave processing performed on the received signal by the deinterleave means is time deinterleave processing, and the operation parameter of the second circuit component determined by the second change determining means From the time when the operation parameter changing means changes by the change amount determined by the second change determining means, the first change of the operation parameter of the first circuit component determined by the first change determining means is performed. It is preferable that the operation parameter change unit does not change the operation parameter of the second circuit component until the time interleave length has elapsed after the operation parameter change unit has changed by the change amount determined by the determination unit. .

  In the method for controlling a digital demodulator according to the present invention, the deinterleaving process performed on the received signal by the deinterleaving means is a time deinterleaving process, and the second circuit determined in the second change determining step is used. The operation parameter of the first circuit component determined in the first change determination step from the time when the operation parameter change means changes the operation parameter of the component by the change amount determined in the second change determination step. Until the time when the time interleave length elapses after the operation parameter change means changes the change amount determined in the first change determination step by the operation parameter change means. Without changing the parameter, the operating parameter changing means changes the operating parameter of the first circuit component. Later, it is preferable that the operating parameters of the second circuit component operating parameters before change from operating parameters of the changed by changing amount determined by the second change determining step returns said operating parameter changing means.

  According to the above configuration, after the influence of the error caused by the change of the operation parameter related to the first circuit component is sufficiently reduced, the operation parameter related to the second circuit component is returned before the change. For this reason, since the effect of reducing the error amount due to the change of the operation parameter related to the second circuit component is ensured for a long time, the error caused by the change of the operation parameter related to the first circuit component can be corrected more. easy.

  In the digital demodulator of the present invention, the first circuit component and the change amount related to the operation parameter of the first circuit component are set to the first circuit component so that power consumption of the first circuit component is reduced. Preferably, the change determining means determines. According to said structure, the power consumption of the whole digital demodulator can be suppressed low.

  In the present invention, the operation parameter changing means before the operation parameter changing means changes the operation parameter of the first circuit component determined by the first change determining means by the change amount determined by the first change determining means. An error amount deriving unit for deriving an amount of pre-change error included in the received signal, wherein the first correction possibility determination unit includes the virtual error amount estimated by the error estimation unit and the error amount deriving unit; It is preferable to determine whether or not the error correction means can correct an error to be included in the received signal from the amount of the error before change derived from the above. According to the above configuration, the amount of error contained in the received signal before the operation parameter is changed is derived, so whether or not error correction is possible according to the error before the change. A more accurate determination can be made.

  In the present invention, the error amount deriving means is constructed in the demodulator, and the correction possibility judging means is constructed in the tuner, respectively, and the error amount deriving means derived by the error amount deriving means in the demodulator is before the change. Preferably, the tuner receives an error amount from the demodulator. According to the above configuration, the error amount before change calculated when the demodulator performs demodulation processing on the received signal can be used to determine whether correction is possible. The exact amount is used to determine correctability.

  Further, in the present invention, the error amount deriving unit causes the operation parameter of the first circuit component determined by the first change determining unit to be equal to the operation parameter by the change amount determined by the first change determining unit. It is preferable to have error rate deriving means for deriving the error rate of the received signal before the changing means changes. According to the above configuration, it is possible to more accurately determine whether or not error correction is possible based on the error rate before the operation parameter is changed.

  Further, in the present invention, the error amount deriving unit causes the operation parameter of the first circuit component determined by the first change determining unit to be equal to the operation parameter by the change amount determined by the first change determining unit. It is preferable to have a deviation derivation means for deriving a deviation from the specified value of the constellation of the received signal before the changing means changes. According to the above configuration, it is possible to make a more accurate determination as to whether error correction is possible based on a deviation from the constellation stipulated value before the operation parameter is changed.

  Further, in the present invention, the error amount deriving unit causes the operation parameter of the first circuit component determined by the first change determining unit to be equal to the operation parameter by the change amount determined by the first change determining unit. It is preferable to have CN ratio deriving means for deriving the CN ratio of the received signal before the changing means changes. According to the above configuration, it can be determined whether or not error correction can be performed more accurately based on the CN ratio before the operation parameter is changed.

  In the present invention, the operation parameter changing unit changes the operation parameter of the first circuit component determined by the first change determining unit a plurality of times by the change amount determined by the first change determining unit. It is preferable that the operating parameter changing unit changes the operating parameter of the first circuit component so that the range occupied by the error does not overlap each other in the received signals after the deinterleave processing. According to the above configuration, control is performed so that errors due to the change of the operation parameter do not overlap after the deinterleaving process, so that an error caused by the change of the operation parameter can be suppressed to a more correctable range.

  In the present invention, the deinterleaving process performed by the deinterleaving unit is a time deinterleaving process, and the operation parameter change related to the first circuit component performed by the operation parameter changing unit is within a time interleave length range. It is preferable that it is once or less. According to the above configuration, since errors generated by the control do not overlap after the time deinterleave processing, the errors generated by the control can be suppressed to a range that can be corrected more reliably.

  Further, in the present invention, the operation parameter of the first circuit component determined by the first change determining means at the timing at which the first circuit component handles the front ends of a plurality of unit signals included in the received signal. It is preferable that the operation parameter changing unit changes the amount of change determined by the first change determining unit. According to the above configuration, the range in which the error caused by the change of the operation parameter in the first circuit component affects is suppressed to the minimum unit signal.

  In the present invention, the operation parameter changing means changes the operation parameter of the first circuit component determined by the first change determining means by the amount of change determined by the first change determining means. It is preferable that the range of the received signal before the time deinterleaving process of the error to be generated is within the range of one symbol. According to the above configuration, the range affected by the error caused by the change of the operation parameter in the first circuit component is limited to the range of one time interleave length in the received signal after the time deinterleave processing.

  In the present invention, the tuner includes an RF amplifier, a mixer, a filter, an IF amplifier, and a VCO / PLL, and the first or second change determining means determines the first or second. The circuit component is preferably one of an RF amplifier, a mixer, a filter, an IF amplifier, and a VCO / PLL. According to the above configuration, the optimum operation parameter can be changed based on the determination as to whether error correction is possible in each circuit component constituting the tuner.

  In the present invention, it is preferable that the error estimation unit estimates the amount of the virtual error based on at least one of a modulation scheme and a coding rate in the received signal. According to the above configuration, information sufficient to estimate the amount of error that is expected to occur due to a change in the operating parameter is ensured, and it can be determined more accurately whether error correction is possible.

  In the present invention, it is preferable that the error estimation means is built in the tuner, and the tuner receives at least one of a modulation scheme and a coding rate in the received signal from the demodulator. According to the above configuration, the amount of virtual errors can be estimated based on accurate information acquired when demodulation processing is performed in the demodulator.

  In the present invention, the first change determining means determines the amount of change of the operation parameter in the first circuit component and the first circuit component for a plurality of times, and the error estimating means includes the first The total virtual errors that are generated in the received signal by the operation parameter changing unit changing the operation parameter of the first circuit component a plurality of times according to the change amount for the plurality of times determined by one change determining unit. It is preferred to estimate the amount. According to the above configuration, it is possible to determine an appropriate change amount of the operation parameter in the second circuit component corresponding to the change of the operation parameter in the first circuit component multiple times.

  In the present invention, each of the first and second circuit components includes a plurality of small circuit components, and the first and second change determining means constitute the first and second circuit components. Preferably, the amount of change of the operating parameter in at least one of the small circuit components to be determined is determined. According to the above configuration, since the operation parameter is changed for each smaller circuit component constituting the first and second circuit components, an appropriate change of the operation parameter can be selected.

  In the present invention, each of the first and second circuit components is composed of a plurality of small circuit components, and m (m is a natural number) among the small circuit components constituting the second circuit component. When both of the first and second correction enable / disable determining means determine that the error correcting means cannot correct an error that will be included in the received signal when the operating parameter is changed, It is preferable that the second change determining means determines the amount of change of the operation parameter in n (n is a natural number), which is larger than m of the small circuit components constituting the circuit component. According to the above configuration, since more operation parameters are changed in the second circuit component, the degree to which errors are reduced by changing the operation parameter in the second circuit component can be increased.

  The digital demodulator according to the present invention can be employed in various digital receivers such as mobile phones and digital TVs that perform reproduction processing of at least one of data such as characters, images, programs, and sounds. Such a digital receiving apparatus acquires information relating to data such as characters, images, programs, voices, and the like from the received signal demodulated by the digital demodulating apparatus of the present invention, and performs processing for reproducing characters and the like.

  The above-described program for a digital demodulator of the present invention is a removable recording medium such as a CD-ROM (Compact Disc Read Only Memory) disk, flexible disk (FD), or MO (Magneto Optical) disk, or a fixed hard disk or the like. In addition to being able to be recorded and distributed on a computer-readable recording medium such as a type recording medium, it can be distributed via a communication network such as the Internet by wired or wireless telecommunication means. In addition, these programs may not be dedicated to the digital demodulator, but may be programs that cause a general-purpose processor to function as a digital demodulator by being used in combination with a program related to channel selection processing or digital demodulation processing. There may be.

  Further, in this specification, the “circuit component” means a circuit component constituting a tuner or a circuit component constituting a demodulator. Specifically, for example, a circuit configuring each unit included in the tuner 2 illustrated in FIG. 2, a circuit configuring each unit of the demodulation unit 301 included in the demodulator 3 illustrated in FIG. Any unit of components such as a component equivalent to one transistor constituting the circuit can correspond to a circuit component. Further, the “small circuit component” with respect to the circuit component indicates a circuit, component, or the like in a unit smaller than the circuit component. For example, when the circuit component indicates an RF amplifier or the like, the small circuit component indicates a component such as a transistor constituting the RF amplifier or the like.

  The following is a description of a digital demodulator which is a preferred embodiment of the present invention. FIG. 1 shows an overall schematic configuration of the digital demodulator 1.

  The digital demodulator 1 of the present invention is provided in a mobile phone 201 (digital receiver). The signal Sr received from the antenna by the mobile phone 201 is demodulated by the digital demodulator 1. Then, information related to data such as characters, images, sounds, and programs is extracted from the demodulated signal output from the digital demodulator 1, and the data such as characters, images, sounds, and programs are reproduced, and the mobile phone 201 is reproduced. Is provided to a telephone user through a display, a speaker, etc. (not shown) provided in the telephone. The digital demodulator 1 may be employed in a digital TV, a wireless LAN device, a PC equipped with a wireless LAN, etc. (hereinafter, a digital receiving device) in addition to a mobile phone.

  The digital demodulator 1 includes a tuner 2, a demodulator 3, and a control unit 4. The tuner 2 is electrically connected to the demodulator 3. The tuner 2 is electrically connected to an antenna or the like, and receives a signal using the antenna or the like. The tuner 2 amplifies the received signal Sr, converts the signal Sr into an IF (Intermediate Frequency) signal Si, and transmits the signal Sr to the demodulator 3. The demodulator 3 receives the IF signal transmitted from the tuner 2, forms a demodulated signal such as a TS (Transport Stream) signal from the IF signal, and outputs the demodulated signal. The control unit 4 controls the operations of the tuner 2 and the demodulator 3.

<Tuner>
The following is a description of the tuner 2. FIG. 2 is a diagram illustrating a configuration of the tuner 2.

  The tuner 2 includes an RF amplifier unit 21, a mixer unit 22, a VCO / PLL unit 23, a filter unit 24, and an IF amplifier unit 25. The signal Sr received by the tuner 2 is amplified by the RF amplifier unit 21 and sent to the mixer unit 22. On the other hand, the VCO / PLL unit 23 forms a mixing signal based on the frequency corresponding to a specific channel in accordance with the channel control signal sent from the control unit 4 (channel selection process). The mixing signal formed by the VCO / PLL unit 23 is sent to the mixer unit 22. The mixer unit 22 mixes the signal Sr sent from the RF amplifier unit 21 and the mixing signal sent from the VCO / PLL unit 23 to form an IF signal corresponding to the IF frequency.

  The IF signal formed by the mixer unit 22 is sent to the filter unit 24. The filter unit 24 removes unnecessary signal components from the IF signal sent from the mixer unit 22. The IF signal Si from which unnecessary signal components are removed is sent to the IF amplifier unit 25, amplified by the IF amplifier unit 25, and transmitted to the demodulator 3.

<Received signal>
The following is a description of the signal Sr received by the tuner 2. As an example of the present embodiment, a case where a transmission system related to digital terrestrial broadcasting in Japan is adopted in the transmission of the signal Sr is shown. In this case, the signal Sr received by the tuner 2 relates to an ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) system. An OFDM (Orthogonal Frequency Division Multiplexing) method is adopted as the transmission method of the ISDB-T method.

  Note that the received signal of the digital demodulator according to this embodiment may be a signal that employs a guard interval. Therefore, in addition to the above ISDB-T system, European DAB (Digital Audio Broadcasting), DVB-T (Digital Video Broadcasting-Terrestrial), DVB-H (-Handheld) system, Korean DMB (Digital Multimedia Broadcasting) system, An IEEE 802.11a / b / g / n method used for a wireless LAN may be used. Furthermore, the present invention may be applied to a cable TV or the like without an antenna that employs an OFDM scheme and a guard interval.

  The OFDM scheme is a transmission scheme as follows. First, this method is a multi-carrier method in which a plurality of carrier waves having different frequencies are used for carrying data. The carriers used in the OFDM system have waveforms that are orthogonal to each other. Here, “the two waveforms are orthogonal” means that the function (inner product) obtained by multiplying each function representing the amplitude of the wave with respect to time and performing time integration in an integration range corresponding to one period becomes zero. Say.

  At the time of data transmission, a modulated signal is formed by superimposing a plurality of carriers modulated according to each value of data to be transmitted. That is, each data value is distributed to a different carrier according to the arrangement order of a plurality of data values included in the transmitted data. Then, the carrier wave is modulated according to the distributed data value, and an OFDM signal is formed by superimposing the plurality of modulated carrier waves. Forming an OFDM signal in this way in the OFDM scheme is equivalent to performing an inverse Fourier transform. In the following description, the effective symbol length refers to the reciprocal of the frequency interval of the carrier used in the OFDM system.

  Next, in order to reduce the influence of delayed waves other than the direct wave, a guard interval is further inserted into the modulated signal in which a plurality of carriers modulated as described above are superimposed. The guard interval is obtained by copying a part of one end of this signal at the other end for each signal (corresponding to the main signal) per effective symbol length in the modulated signal. The modulated signal with the guard interval inserted in this way is transmitted as an OFDM signal.

  A signal composed of an effective symbol length signal and a guard interval length is called one symbol. An OFDM signal is composed of a plurality of such symbols. When a signal in which an OFDM signal and a delayed wave that is delayed in time and arrives at the reception side is received is received, a portion where signals included in different symbols are overlapped is included in the received signal. The guard interval is used to extract a portion where signals included in different symbols do not overlap.

  In terrestrial digital broadcasting, encoding is performed on data transmitted by an OFDM signal to correct errors generated by noise and interference waves generated in the transmission path. For encoding, Reed-Solomon code (RS code) and Viterbi code are used. In the RS code used in terrestrial digital broadcasting, the last 16 bytes of the transmitted 204 bytes of data are check bits, and an error of up to 8 bytes in 204 bytes can be corrected.

In the Viterbi code, with respect to n bits to be transmitted after encoding, the encoding rate when the data before encoding is k bits is k / n, and 1/2 to 7/8 is standardized. Has been. In order to restore the RS-encoded and Viterbi-encoded data, RS decoding and Viterbi decoding are performed on the receiving side. In the present embodiment, “error correction is possible” refers to a case where the bit error rate after decoding is a predetermined value or less. For example, a case where the bit error rate after RS decoding is 1 × 10 ⁻¹¹ or less is a case where error correction by RS decoding and Viterbi decoding is possible.

  By the way, depending on the state of the transmission path, there may occur a burst error in which errors are concentrated on a transmission signal in terms of time or frequency. In addition, after Viterbi decoding for restoring a Viterbi-encoded signal, burst errors generally occur in many cases. When an error occurring in a signal having a certain length is corrected by error correction as described above, the number of errors that can be corrected per signal having this length is limited. Therefore, when a burst error as described above occurs, it may be impossible to correct the error.

  In terrestrial digital broadcasting, various interleaving processes are performed on data transmitted by a transmission signal so that error correction is possible even when a burst error occurs in the transmission signal. Interleaving includes bit interleaving, byte interleaving, time interleaving, and frequency interleaving, and rearranges data corresponding to signals included in a transmission signal in terms of time and frequency. In particular, there is temporal interleaving for the purpose of rearranging temporally continuous signals. In addition, there is frequency interleaving in order to rearrange a plurality of carrier waves that are continuous in frequency at random in frequency. For example, time interleaving and time deinterleaving for returning the data subjected to time interleaving to the original are performed as follows.

  FIG. 3 is a schematic diagram illustrating an example of time interleaving and time deinterleaving. FIG. 3 shows three signals before and after the interleaving and deinterleaving processing. As shown in FIG. 3, these three signals are composed of a plurality of symbols Sb that are continuous in time.

  The modulated OFDM signal Sr consisting of a plurality of carriers is rearranged as shown in FIG. 3 according to a predetermined order for each data corresponding to the length of the symbol Sb by time interleaving. When a signal corresponding to the rearranged data is transmitted, a burst error 101 occurs in a part of the signal depending on the state of the transmission path. When this signal is received, time deinterleaving is performed on the receiving side. Data once rearranged by time interleaving is returned to the original order again by time deinterleaving. Here, the burst error 101 generated across a plurality of symbols in the transmission path is dispersed like the error 102 for each symbol by time deinterleaving.

  As shown in FIG. 3, the symbols are rearranged so that each symbol moves to a position after the temporal position before the time interleaving by the time interleaving. Further, signals included in carrier waves having different frequencies in each symbol are included in different temporal positions in the rearranged signals.

  As described above, even when a burst error in which errors are concentrated in time occurs, the error is distributed after time deinterleaving, so that error correction can be performed.

  In byte interleaving, rearrangement of signals in units of bytes is performed so that data is distributed in units of 204-byte RS encoding. In bit interleaving, signals are rearranged in bit units. Further, in frequency interleaving, symbols are rearranged across the carriers included in the OFDM signal Sr.

  In terrestrial digital broadcasting, in addition to this, energy diffusion is performed in order to prevent energy bias of transmission signals due to data bias. Energy diffusion is performed by randomizing data by taking a bitwise exclusive OR of pseudo-random data and data related to a transmission signal.

<Demodulator>
The following is a description of the demodulator 3. FIG. 4A is a block diagram showing the configuration of the demodulator 3. As shown in FIG. 4A, the demodulator 3 includes a plurality of components such as an ADC unit 31 shown below. Each of the following components may be a component having a circuit specialized to perform each function, or a general-purpose CPU, RAM, etc., and a program that causes the CPU to function to perform each of the following functions. It may be composed of In the latter case, the FFT unit 33 and the like described below are constructed by combining hardware such as a CPU and a program.

  The demodulator 3 includes an ADC unit 31, an AFC / symbol synchronization unit 32, an FFT unit 33, a frame synchronization unit 34, a detection unit 35, a waveform equalization unit 37, and an error correction unit 36. The demodulator 3 performs demodulation processing and error correction processing on the IF signal.

  The IF signal transmitted from the tuner 2 is input to the ADC unit 31. The ADC unit 31 converts the input IF signal, which is an analog signal, into a digital signal, and sends the converted digital signal to the AFC / symbol synchronization unit 32. The AFC / symbol synchronization unit 32 performs correction processing such as filter processing on the digital signal sent from the ADC unit. Then, the AFC / symbol synchronization unit 32 determines a starting point of Fourier transform by the FFT unit 33 described later, that is, a symbol synchronization point. Then, the synchronized digital signal is sent to the FFT unit 33. Further, the AFC / symbol synchronization unit 32 derives information related to the mode indicating the effective symbol length, and sends the information related to the mode to the tuner control unit 4. Modes indicating the effective symbol length include mode 1 (effective symbol length 252 μs), mode 2 (effective symbol length 504 μs), and mode 3 (effective symbol length 1008 μs).

  In the determination of the symbol synchronization point, a point at which optimum reception with the least influence of delayed waves and the like that arrive after delay is possible is set as the synchronization point. As a method of determining such a synchronization point, a method of referring to signal correlation, a method of correcting a phase shift using a pilot signal, or the like is used.

  An FFT (Fast Fourier Transform) unit 33 performs Fourier (time-frequency) conversion on the digital signal sent from the AFC / symbol synchronization unit 32. A so-called fast Fourier transform (FFT) is generally used for the Fourier transform. That is, since this digital signal is an OFDM signal, it has a waveform obtained by inverse Fourier transform, that is, a waveform in which a plurality of carrier waves modulated according to data values are superimposed. The FFT unit 33 extracts a plurality of carrier waves modulated according to the data value from the superimposed waveforms by Fourier transform. Then, the FFT unit 33 rearranges the digital signals corresponding to the respective data values distributed to the respective carrier waves so as to be temporally aligned in the original arrangement order of the data, and the digital corresponding to the data before forming the OFDM signal Reshape the signal. Then, the FFT unit 33 sends this digital signal to the frame synchronization unit 34.

  The frame synchronization unit 34 synchronizes the digital signal sent from the FFT unit 33 in units of frames. One frame is composed of, for example, 204 symbols, and one set of TMCC information is acquired from one frame signal. The digital signal synchronized by the frame synchronization unit 34 is sent to the waveform equalization unit 37 and simultaneously sent to the detection unit 35.

  The waveform equalizer 37 performs waveform equalization on the digital signal synchronized by the frame synchronizer 34 based on the scattered pilot signal included in the digital signal. Then, after performing signal correction by waveform equalization, the digital signal corresponding to the data value is demodulated, and the demodulated digital signal is sent to the error correction unit 36. The waveform equalizing unit 37 derives a difference between the constellation of each carrier wave subjected to waveform equalization based on a scattered pilot signal included in the digital signal and a specified value (deviation derivation unit). Then, information on the MER (Modulation Error Ratio) or CN ratio of the received signal is extracted from the difference between the derived constellation and the specified value. Further, the MER or CN ratio is sent to the control unit 4.

  On the other hand, the detection unit 35 extracts TMCC information included in the digital signal. Then, the extracted MER or CN ratio and information related to TMCC are sent to the control unit 4. TMCC information includes carrier modulation schemes such as 64QAM, 16QAM, and QPSK, convolutional coding rates (1/2, 2/3, 3/4, 5/6, 7/8), guard interval length, and other transmission schemes. Such information is included. Further, as the guard interval length, lengths of 1/4, 1/8, 1/16 and 1/32 of the effective symbol are employed.

  The error correction unit 36 includes a deinterleave unit 41, a decoding unit 42, and an energy despreading unit 43, as shown in FIG. The deinterleave unit 41 performs deinterleave processing on the digital signal transmitted from the waveform equalization unit 37. As shown in FIG. 4B, the deinterleave unit 41 includes a frequency deinterleave unit 51, a time deinterleave unit 52, a bit deinterleave unit 53, and a byte deinterleave unit 54. These deinterleaving sections 51 to 54 perform frequency deinterleaving, time deinterleaving, bit deinterleaving, and byte deinterleaving corresponding to various interleavings as described above. The digital signal that has been subjected to various interleaving processes is returned to the digital signal before the interleaving process by these deinterleaving processes.

  The decoding unit 42 decodes the digital signal sent from the waveform equalization unit 37. The decoding unit 42 includes a Viterbi decoding unit 61 and an RS decoding unit 62 as shown in FIG. These decoding units 61 and 62 perform Viterbi decoding and RS decoding as described above, respectively. By these decoding, the digital signal subjected to Viterbi encoding and RS encoding is returned to the digital signal before encoding.

  The energy despreading unit 43 returns the digital signal sent from the detection unit 35 to the digital signal before being subjected to energy diffusion.

  These various deinterleaving, decoding, and energy despreading are performed in an order corresponding to the various interleaving, encoding, and energy spreading performed on the transmission side. In the case of ISDB-T, frequency deinterleaving, time deinterleaving, bit deinterleaving, Viterbi decoding, byte deinterleaving, energy despreading, and RS decoding are performed in this order.

  Note that the error correction unit 36 calculates the bit error rate of the digital signal based on the number of corrected errors (error rate deriving means). Then, the calculated bit error rate is sent to the control unit 4. This bit error rate may be a ratio of the number of bits corrected by Viterbi decoding and RS decoding to the number of bits of the signal immediately after the bit deinterleaving process is performed. Alternatively, it may be the ratio of the number of bits corrected by RS decoding to the number of bits of the signal immediately after the byte deinterleaving process is performed.

<Operation parameter change based on error correction judgment>
The following is a description of changes in operating parameters of the tuner 2 and the like based on determination of whether error correction is possible. In the following, it is assumed that the signal state is stable, and errors other than errors caused by changing the operating parameters are always constant unless otherwise specified. In the following, the first embodiment related to the operation parameter change control will be described first, and then the second embodiment will be described.

[First Embodiment]
The control unit 4 performs control to change various operation parameters in the tuner 2 and the demodulator 3 as described above. For example, the control unit 4 changes the operation parameter related to the power consumption of the VCO / PLL unit 23 so that the power consumption of the VCO / PLL unit 23 and the like is reduced. However, if the operation parameters of the components of the tuner 2 are changed in this way, an error may occur in the IF signal Si. FIG. 5 shows an error that occurs in the signal Si due to such a change in operating parameters. In the present embodiment, as shown in FIG. 5, it is assumed that the influence of errors falls within one symbol.

  A curve 71 indicates an error that occurs in the received signal due to, for example, the control unit 4 changing an operation parameter of a certain part of the tuner 2. If such an error 74a finally remains in the signal Si, accurate data cannot be acquired when acquiring data from the signal Si after demodulating the received signal Sr.

  On the other hand, a signal included in one symbol of the signal Si including a plurality of symbols Sb is dispersed in the range of the time interleave length Li by time deinterleaving in the demodulator 3. The error 74a generated by changing the operation parameter in the components of the tuner 2 as described above is dispersed within the period P1 by the time deinterleaving process, as indicated by the one-dot chain arrow in FIG. As a result, the error 74a is dispersed into the error 74b. The distributed error 74 b is corrected by the error correction unit 36.

  However, as illustrated in FIG. 5, the error amount of the error 74b may exceed a threshold that can be corrected by the error correction unit 36 even after dispersion by time deinterleaving processing. In such a case, the error correction unit 36 cannot correct the error 74b. Therefore, when it is expected that the error correction unit 36 cannot correct the error after distribution, the control unit 4 has the following configuration so that the error after distribution can be corrected. FIG. 6 is a block diagram illustrating a configuration of the control unit 4. The control unit 4 includes an error estimation unit 91, a correctability determination unit 92, a change determination unit 93, and an operation parameter change unit 94.

  The error estimation unit 91 estimates the amount of virtual errors that will occur in the signal Si when it is assumed that the control unit 4 has changed the operating parameters of the components of the tuner 2 and the demodulator 3. Specifically, the amount of error depends on components related to the operation parameter being changed and the amount of change, a carrier modulation scheme, a coding rate, and other variables. Therefore, the error estimation unit 91 holds a table indicating the correspondence between these variables and the error amounts in advance. Then, the error estimation unit 91 derives the amount of error that occurs from such a table and the TMCC information including the carrier modulation scheme transmitted from the detection unit 35 as described above. Alternatively, the error estimation unit 91 may obtain an error amount generated from a function of the error amount related to these variables.

  When the operation parameter is continuously changed a plurality of times for the first part, the error estimation unit 91 estimates the total error generated by the change of the operation parameter in the first part. . In the following determination by the correctability determination unit 92, the total error amount estimated by the error estimation unit 91 is used.

  The correctability determination unit 92 uses the error amount estimated by the error estimation unit 91 and the error rate sent from the error correction unit 36, and the total amount of errors per time interleave length that the signal Si includes due to the change of the operation parameter Is calculated. Then, the calculated total amount of errors is divided by the time interleave length to calculate an error in the signal Sd after the time deinterleave processing. On the other hand, the correctability determination unit 92 holds the maximum error amount that can be corrected by the error correction unit 36 as a threshold value. When the error in the signal Sd after the time deinterleaving process calculated as described above exceeds the threshold value, the correction possibility determination unit 92 causes the error correction unit 36 to detect an error that the signal Sd includes due to the change of the operation parameter. Judge that it cannot be corrected. When the total amount of errors is less than or equal to the threshold value, the correction possibility determination unit 92 determines that the error correction unit 36 can correct an error included in the signal Sd by changing the operation parameter. Since the case where the signal state is stable as described above is assumed, the error rate or the like sent from the demodulator 3 may be an average value in a certain time range.

  The error estimator 91 may derive the error generated by the change of the operation parameter by the amount of noise generated by the change of the operation parameter. Then, based on the amount of noise derived by the error estimation unit 91 and the information on the CN ratio sent from the detection unit 35, the CN ratio corresponding to the total amount of errors included in the signal Si due to the change of the operation parameter is obtained. It may be sought. Alternatively, the error estimation unit 91 is included in the signal Si by the change of the operation parameter, based on the difference between the amount of error generated by the change of the operation parameter and the specified value of the constellation sent from the FFT unit 33. The total amount of errors may be derived.

  As described above, in order to measure the error amount (pre-control error amount) included in the signal Si before the operation parameter is changed (error amount deriving means), in addition to the error rate, the above-described value derived in the demodulator 3 is used. A CN ratio, a deviation from a constellation prescribed value, or the like may be used. When determining whether correction is possible, a threshold corresponding to a deviation from the CN ratio corresponding to the error amount or the constellation specified value is used. That is, the correction availability determination unit 92 determines whether or not error correction is possible based on the comparison between the CN ratio corresponding to the error amount and the total error amount estimated by the error estimation unit 91 and the threshold corresponding to the CN ratio. Since the case where the signal state is stable as described above is assumed, the CN ratio or the like derived in the demodulator 3 may be an average value in a certain time range.

  The threshold value of the error amount held by the correctability determination unit 92 is set so that the error can be corrected to the maximum value by RS decoding and Viterbi decoding. However, the correctable value differs depending on the carrier modulation scheme and the coding rate of the convolutional code. For this reason, the correctability determination unit 92 holds in advance a table indicating the correspondence relationship between the carrier modulation scheme and the like and various threshold values, and obtains an appropriate threshold value from such a table and TMCC information. Threshold deriving means).

  Further, when the signal state of the reception signal Sr (signal Si) is unstable, the error amount threshold value may be set smaller than the maximum correctable value as described above. As a result, for example, even when the CN ratio changes or the signal strength decreases in a short time, it is determined whether or not correction can be performed more reliably. On the contrary, when the signal state of the reception signal Sr (signal Si) is stable, it is considered that the CN ratio does not change in a short time, and therefore it may be set to a value close to the maximum value that can be corrected. As a result, the operation parameter can be changed more flexibly according to the signal state.

  The change determination unit 93 determines first, second, and third parts that the operation parameter change unit 94 (to be described later) changes, and the amount of change of the operation parameter related to each part. Specifically, the change determination unit 93 first determines the first component whose operation parameter is to be changed and the operation parameter change amount related to the first component (first change determination means). The change of the operation parameter related to the first component includes, for example, reducing the power consumption of the VCO / PLL unit 23 as described above. Next, the correctability determination unit 92 determines whether or not the error that the signal Si includes when the operation parameter is changed with the first component and the change amount determined by the change determination unit 93 can be corrected. .

  When the correction possibility determination unit 92 determines that the error correction is impossible, the change determination unit 93 sets the second parameter whose operation parameter is changed by the operation parameter change unit 94 to be described later and the operation parameter related to the second component. A change amount is determined (second change determination means). Here, the change determination unit 93 sets the second value so that the total amount of errors that are included in the signal Si due to the change of the operation parameter related to the first component falls within the range that the error correction unit 36 can correct. Determine parts and amount of change. Specifically, it is as follows.

  The change determination unit 93 holds an error reduction component table in which components that reduce errors that are included in the signal Si by changing operation parameters are listed. The error reduction component table includes information relating to the relationship between the amount of change in the operation parameter of such a component and the amount of error reduction that is to be reduced depending on the amount of change. For example, as the amount of amplification by which the RF amplifier unit 21 of the tuner 2 amplifies the signal increases, the amount of noise relative to the signal decreases. In this case, the error reduction component table includes information indicating the relationship between the amount of change in the amplification amount in the RF amplifier unit 21 and the amount of reduction in the error amount in the signal. Alternatively, the error reduction component table is a relationship between an increase in correction performance that the error correction unit 36 of the demodulator 3 corrects an error and a difference in error amount that can be corrected by the error correction unit 36 before and after the increase in correction performance. Is included.

  Note that the error reduction component table may have a relationship between the absolute amount of the operation parameter and the absolute amount of error, instead of the relationship between the change amount of the operation parameter and the reduction amount of the error.

  The change determination unit 93 selects the second component from the components listed in the error reduction component table. Then, from the amount of error expected to be included in the signal Si when the operation parameter related to the first component is changed, the operation parameter related to the second component necessary to make this error amount correctable. The amount of change is derived.

  Next, the change determination unit 93 determines a timing T1 when the operation parameter related to the first component is changed and a timing T2 when the operation parameter related to the second component is changed. The timings T1 and T2 may be determined uniformly so as to be separated from each other in time by a time interleave length Li or more. Alternatively, the timings T1 and T2 are brought close in time to the limit that the error correction unit 36 can correct an error that is included in the signal Si by changing the operation parameter in the first and second components. May be determined.

  Further, it is preferable that the timing T1 is determined to be performed at most once within the range of the time interleave length Li when the operation parameter related to the first component is changed a plurality of times. That is, it is preferable that the timing T1 is determined so that errors that are included in the signal Sd after time deinterleaving do not overlap when the operation parameter related to the first component is changed a plurality of times. Thus, the error correction unit 36 can more reliably correct an error that is included in the signal Sd when the operation parameter of the first component is changed a plurality of times.

  Furthermore, the timing T1 is preferably determined in accordance with the timing at which the first component handles the tip of each symbol (unit signal) included in the signal Sr. As a result, the range affected by the error that occurs due to a single change of the operating parameter is suppressed to the minimum number of symbols. Further, the amount of change of the operation parameter relating to the first component and the first component is adjusted so that the error occurring in the signal Si before time deinterleaving is within the range of one symbol due to the change of the operation parameter. Is preferred. As a result, the range in which the error is dispersed after dispersion by time deinterleaving is suppressed within the range of the time interleave length in the signal Sd after time deinterleaving.

  As described above, it is preferable that the change amount related to the second component is determined so that the error amount included in the signal Si is within a range in which the error correction unit 36 can correct the error. However, the operation parameter related to the second component may be changed with an arbitrary change amount regardless of whether or not the error amount is within a correctable range. Also by this, more accurate information can be obtained from the signal Si as compared with the case where the operation parameter related to the second component is not changed.

  Further, the change determination unit 93 determines the third component for changing the operation parameter, the change amount of the operation parameter related to the third component, and the change timing T3. The third part is determined to be the same part as the second part. The change amount of the operation parameter related to the third component is determined by the difference between the operation parameter before the change of the operation parameter related to the second component and the operation parameter after the change. Further, the timing T3 may be uniformly determined so as to be temporally separated from the timing T2 by the time interleave length Li or more. Alternatively, the error that is included in the signal Si by changing the operation parameter in the first to third parts is determined in time proximity to the timing T2 to the limit that the error correction unit 36 can correct. May be. By changing the operation parameter with the third component and the change amount determined in this way, the operation parameter of the second component is returned to the state before the change at the timing T2.

  When the operation parameter is changed so that the error is reduced by the change of the operation parameter related to the second part, generally, the power consumption of the second part often increases. According to the above configuration, for example, when the amplification amount of the RF amplifier unit 21 is increased, the second component whose power consumption has increased due to the change of the operation parameter related to the second component is the original power consumption state. Returned to In addition, when it is not necessary to return before the change of the operation parameter concerning a 2nd component, determination of the change amount of a 3rd component and this operation parameter does not need to be performed.

  By the way, in the above, the specific objects of the first to third parts are, for example, circuits constituting each part of the tuner 2 shown in FIG. 2 and the demodulator 3 shown in FIG. These are parts of every unit such as circuits constituting each part of the demodulator 301 and parts equivalent to one transistor constituting these circuits. The first to third parts may be parts of different units. That is, the first component may be a circuit composed of a plurality of transistors and the second component may be composed of one transistor, or the first component may be composed of one transistor and the second component The part may be a circuit composed of a plurality of transistors. When the first and second parts are composed of a plurality of transistors, the operation parameters of one or a plurality of transistors among the plurality of transistors constituting the first and second parts are changed.

  Further, even if the operation parameters related to a plurality of small parts, which are smaller parts constituting the second part, are changed, the error generated in the signal Si cannot be corrected due to the change of the operation parameters related to the first part. When the correctability determination unit 92 determines, it is preferable to increase the number of small parts whose operation parameters are changed in the second part. In other words, if the error cannot be corrected even if the operation parameters of m small parts (m is a natural number) are changed in the second part, the operation is performed on n (n is a natural number) small parts greater than m. Preferably, the amount of change of the operating parameter is determined so that the parameter is changed. As more operating parameters are changed in the second part, the degree of error reduction increases.

  The operation parameter changing unit 94 changes the operation parameters of the first to third components determined by the change determining unit 93 as described above by the respective change amounts determined by the change determining unit 93 (parameter change control means). At this time, the change of each operation parameter is performed at the timings T1 to T3 determined by the change determination unit 93.

  FIGS. 7 and 8 show error amounts included in the signal Si and the signal Sd when the operation parameter changing unit 94 changes the operation parameters related to the first to third components. FIG. 7 shows a case where the timings T1 to T3 are separated from each other in time by the time interleave length Li. A curve 71 indicates an error that occurs in the signal Si before time deinterleaving due to the change of the operating parameter in the first part. A curve 172 shows an error in the signal Sd after the time deinterleave processing caused by the change of the operation parameter in the first to third parts.

  At the timing T2, an operation parameter change 81 for the second component is performed. This reduces errors contained in the signal Si as shown by curve 71. Note that the amount of error reduction caused by the operation parameter change 81 is distributed by time deinterleaving. For this reason, as shown by the curve 172, in the signal Sd, errors gradually decrease over the period P2 having the length of the time interleave length Li.

  At timing T1, the operation parameter of the first component is changed. This causes an error 74a in the signal Si. As shown in curve 172, error 74a is distributed in period P1 by time deinterleaving. Since the reference value of the error amount is lowered due to the change 81 of the operation parameter, the error amount in the period P1 is smaller than the threshold value as shown by the curve 172. As a result, even when the operation parameter change 81 is not performed, even when the correct information is not acquired from the signal Si, the error can be corrected, so that the correct information is acquired. As indicated by the curve 71, the tip of the error 74a is aligned with the tip of the symbol 73. In addition, the operation parameter of the first component is changed at most once within the range of the time interleave length Li.

  At timing T3, an operation parameter change 82 for the third component is performed. As a result, the error amount whose reference value has decreased due to the operation parameter change 81 increases to the amount before the operation parameter change 81 is performed. Note that the increase in error due to the change 81 in the operation parameter is distributed over the period P3 by the time deinterleaving process as described above.

  FIG. 8 shows a case where the separation times of timings T1 and T2 and the separation times of T2 and T3 are each less than the time interleave length Li. Therefore, in FIG. 8, the error is reduced by the period P4 in which the error is reduced by the operation parameter change 181 in the second part, the period P1 in which the error 74a is dispersed, and the change in the operation parameter 182 in the third part. The period P5 to be overlapped with each other. However, changes related to the first to third components and each component so that the error included in the signal Sd does not exceed the threshold at T1 or T4 where the error included in the signal Sd after the time deinterleaving process is the largest. The quantity and the timings T1 to T3 are determined. For this reason, as indicated by the curve 172, the error included in the signal Sd caused by the change of the operation parameter in the first to third parts does not exceed the threshold value.

<Overall control flow>
The following is the overall flow of the operation parameter change control according to the first embodiment. FIG. 9 is a flowchart showing such an overall flow.

  First, the change determination unit 93 determines the first component whose operation parameter is to be changed, the change amount relating to the first component, and the timing T1 (S1).

  Next, the error estimation unit 91 estimates the amount of error that will occur in the signal Si when the operation parameter is changed with the first component and the change amount determined in S1 (S2). Then, based on the amount of error estimated in S2 and information such as the error rate sent from the demodulator 3, it is determined whether or not the error correction unit 36 can correct the error included in the signal Si. The unit 92 determines (S3). If it is determined that correction is possible (S3, YES), the timing T1 determined in S1 is compared with the current time (S9). If they do not match, the process of S9 is repeated (S9, NO). When the timing T1 coincides with the current time (S9, YES), the operation parameter changing unit 94 changes the operation parameter related to the first component by the change amount determined in S1 (S10). Then, the operation parameter changing process ends.

  On the other hand, when the error correction availability determination unit 92 determines that correction is impossible in S3 (S3, NO), the change determination unit 93 determines the change amount related to the second component and the second component, and the third component. And the change amount and timing T2 and T3 which concern on a 3rd component are determined (S4).

  Next, it is determined whether or not the timing T2 coincides with the current time (S5). If they do not coincide, the process of S5 is repeated (S5, NO). If they match (S5, YES), the operation parameter changing unit 94 changes the operation parameter of the second part by the change amount determined in S4 (S6).

  Next, it is determined whether or not the timing T1 coincides with the current time (S7). If they do not coincide, the process of S7 is repeated (S7, NO). If they match (S7, YES), the operation parameter changing unit 94 changes the operation parameter of the first part by the change amount determined in S1 (S8).

  Next, it is determined whether or not the timing T3 coincides with the current time (S11). If they do not coincide, the processing of S11 is repeated (S11, NO). If they match (S11, YES), the operation parameter changing unit 94 changes the operation parameter of the third component by the change amount determined in S4 (S12). Then, the operation parameter changing process ends.

[Second Embodiment]
The following is a description of the second embodiment related to operation parameter change control. Since many of the configurations of the second embodiment are the same as the configurations of the first embodiment, description thereof will be omitted as appropriate in the following.

  The second embodiment is different from the first embodiment as follows. First, regardless of whether or not an error caused by the change of the operation parameter related to the first part can be corrected, the change amount and timing T2 of the operation parameter related to the second part and the second part are determined. . Specifically, the change determination unit 93 determines in advance the second component, the change amount, and the timing T2 prior to the change of the operation parameter related to the first component, and holds information related to these. The change determination unit 93 also determines in advance the third component (the same component as the second component), the amount of change and the timing T3 related to the third component. Note that the change determination unit 93 may select a second part or the like from a table relating to information on a plurality of parts and the amount of change.

  If it is determined that the error caused by the change of the operation parameter related to the first part is uncorrectable, the change of the operation parameter related to the first part is changed by the change of the operation parameter related to the second part. A correction propriety determination unit 92 further determines whether or not an error caused by the cause can be corrected (second correction propriety determination unit). If it is determined that the correction is possible, the operation parameter changing unit 94 changes the operation parameters related to the first to third parts. When the correction possibility determination unit 92 determines that correction is not possible, the change of the operation parameter related to the first to third parts is not performed for any of the parts. In addition, when it is determined that an error caused by the change of the operation parameter related to the first part can be corrected without the change of the operation parameter of the second part, only the change of the operation parameter of the first part is performed. Is done.

  Whether or not an error caused by the change of the operation parameter related to the first component can be corrected by the change of the operation parameter related to the second component is determined as follows. First, in the error reduction component table, as in the first embodiment described above, components that reduce errors that are included in the signal Si by changing the operation parameters are listed. However, the error reduction component table of the second embodiment is not the relationship between the change amount of the operation parameter and the decrease amount of the error that is reduced by the change amount, but some numerical values related to the change amount of the operation parameter. , And a reduction amount of error when the operation parameter is changed with each numerical value. Then, the change determination unit 93 selects an arbitrary one from the parts of the error reduction part table as the second part, and selects an arbitrary one from the higher numerical values as the change amount of the operation parameter in the second part. select. The second part and the change amount are determined based on the error amount estimated by the error estimation unit 91 and the like.

  Next, the correction possibility determination unit 92 acquires the error reduction amount corresponding to the second component and the change amount determined by the change determination unit 93 from the error reduction component table. The error amount estimated by the error estimation unit 91 related to the change of the operation parameter in the first part is reduced by the error reduction amount acquired from the error reduction part table by the change of the operation parameter in the second part. is expected. The correctability determination unit 92 derives an error amount reduced by the error reduction amount acquired from the error reduction component table from the error amount estimated by the error estimation unit 91 (total error amount deriving unit). On the other hand, the correctability determination unit 92 holds a threshold value related to the error amount as in the first embodiment. Then, when the amount of error reduced by the reduction amount in the signal Sd after the time deinterleaving processing is equal to or smaller than the threshold value, the correction possibility determination unit 92 determines that the error correction unit 36 can correct this error. To do. That is, the correctability determination unit 92 determines that an error that occurs in the received signal when the operation parameters of the first and second components are changed based on the determination of the change determination unit 93 can be corrected.

  The error amount threshold is derived based on the received signal modulation scheme and coding rate (second threshold deriving means), as in the first embodiment.

  With such a configuration, when an error caused by the change of the operation parameter related to the first component is not correctable, only when the error can be corrected by further changing the operation parameter related to the second component, The operation parameters related to the first to third parts are changed. That is, if the correction is not possible, the operation parameter is not changed, and no error occurs. In addition, when it is determined that correction is possible, the operation parameters of the first to third parts are changed, so that the change of the operation parameters of the first part is ensured, and an error caused by this is ensured. This can be corrected by changing the operation parameter of the second part.

  Further, in the above configuration, compared to the first embodiment in which the second component and the change amount are determined so that they can be corrected, a table indicating the correspondence between the error reduction amount and the change amount is not sufficient. It is necessary and the second part or the like can be easily determined.

  Note that the first component in the second embodiment, the change amount of the operation parameter related to the first component, and the determination of the timing T1 are the same as those in the first embodiment.

<Overall control flow>
The following is the overall flow of the operation parameter change control according to the second embodiment. FIG. 10 is a flowchart showing an overall flow of the operation parameter change control according to the second embodiment.

  First, the change determination unit 93 determines in advance the second and third parts, the change amounts of the operation parameters related to these parts, and the timings T2 and T3 (S21). Even if the second and third parts are not determined each time the operation parameter related to the first part is changed, the predetermined second and third parts are used every time. Good. Then, the change determining unit 93 determines the first component, the amount of change related to the first component, and the timing T1 (S22).

  Next, the error estimation unit 91 estimates the amount of error that will occur in the signal Si when the operation parameter is changed with the first component and the change amount determined in S1 (S23). Then, based on the error amount estimated in S23 and the information such as the error rate sent from the demodulator 3, it is determined whether or not the error correction unit 36 can correct the error included in the signal Si. The unit 92 determines (S24). If it is determined that correction is possible (S24, YES), the timing T1 determined in S22 is compared with the current time (S30). If they do not match, the process of S30 is repeated (S30, NO). When the timing T1 coincides with the current time (S30, YES), the operation parameter changing unit 94 changes the operation parameter related to the first component by the change amount determined in S22 (S31). Then, the operation parameter changing process ends.

  On the other hand, when the error correction possibility determination unit 92 determines that the correction is impossible in S24 (S24, NO), whether or not the correction is possible when the operation parameter of the second part is changed is corrected. The determination unit 92 determines (S25). If it is determined that correction is not possible (S25, NO), the operation parameter changing process is terminated without changing the operation parameter in any of the first to third components.

  On the other hand, when the correction is possible and the correction possibility determination unit 92 determines in S25 (S25, YES), it is determined whether or not the timing T2 matches the current time (S26). The process of S26 is repeated (S26, NO). If they match (S26, YES), the operation parameter changing unit 94 changes the operation parameter of the second part by the change amount determined in S21 (S27).

  Next, it is determined whether or not the timing T1 coincides with the current time (S28). If they do not coincide, the process of S28 is repeated (S28, NO). If they match (S28, YES), the operation parameter changing unit 94 changes the operation parameter of the first component by the change amount determined in S22 (S29).

  Next, it is determined whether or not the timing T3 coincides with the current time (S32). If they do not coincide, the process of S32 is repeated (S32, NO). If they match (S32, YES), the operation parameter changing unit 94 changes the operation parameter of the third component by the change amount determined in S21 (S33). Then, the operation parameter changing process ends.

<Modification>
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims.

  For example, in the above-described embodiment, time interleaving is described in which symbols are rearranged so that each symbol is positioned after the temporal position before interleaving. However, the present invention may be applied when block interleaving is performed in which rearrangement is performed within a predetermined range of blocks in the signal. Further, the present invention may be applied to the case where byte deinterleaving is performed in which rearrangement is performed such that each symbol is positioned after the temporal position before interleaving, as in time deinterleaving.

  Alternatively, the above-described control may be performed according to the frequency deinterleaving process. In this case, for example, the correction possibility determination unit 92 determines whether or not the error correction unit 36 can correct the error after being distributed by frequency deinterleaving. Alternatively, whether to perform control, how many times to perform control, or the like is determined according to the range in which errors are dispersed by frequency deinterleaving.

  Alternatively, in the above-described embodiment, a state where the signal state is stable is assumed, but the present invention can also be applied to a case where the signal state is unstable. When the signal state is stable, an average error rate, CN ratio, etc. in units of time interleave length may be used, but when the signal state is unstable, an average CN ratio in smaller units, etc. May be calculated. As a result, a more precise calculation of the CN ratio or the like is performed, so that it can be reliably determined whether or not the error can be corrected even when the signal state is unstable and the error amount changes in a short time. In the above-described embodiment, an average value such as an error rate is used, but an instantaneous value may be used.

  Or in the above-mentioned embodiment, the bad influence to IF signal Si produced by the change of the operation parameter concerning the 2nd part is not taken into consideration. However, such adverse effects are in a range that can be predicted in advance, and the above-described embodiment may be implemented in consideration of such adverse effects. For example, the first correction possibility determination unit holds in advance information on the amount of error caused by the change of the operation parameter related to the second component, and it is determined whether correction is possible based on such information. May be.

  Alternatively, in the above-described embodiment, it is assumed that an error that occurs due to a change in the operation parameter is within the range of one symbol, but the present invention is applied when an error occurs across a plurality of symbols. May be. In this case, it is considered that errors that occur across a plurality of symbols are distributed to a range that is greater than or equal to the time interleave length by the time deinterleave processing. For example, the time interval between the timings T2 and T3 is set to a time interval longer than the time interleave length.

  Alternatively, in the above-described embodiment, the control unit 4 is formed outside the tuner 2 and the demodulator 3, but each unit included in the control unit 4 may be built inside the tuner 2 and the demodulator 3. Alternatively, the control unit 4 is constructed by a host CPU that controls the entire terminal installed in an information terminal such as a mobile phone in which the digital demodulator of the present embodiment is adopted and a program that causes the CPU to function as the control unit 4 May be.

  Or although control of the control part 4 was performed according to the front-end | tip of a symbol in the above-mentioned embodiment, control may be performed at arbitrary timings.

  Or, in the overall flow of the change of the operation parameter described above, the case where the error amount is estimated once for each change of the operation parameter in the first part or a plurality of times is shown. When the change is performed once, the flow shown in FIG. 9 or 10 may be repeated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an overall schematic configuration of a digital demodulator as an embodiment of the present invention and a schematic diagram of a portable information terminal having the digital demodulator. FIG. 2 is a block diagram illustrating a configuration of a tuner illustrated in FIG. 1. It is a figure which shows the interleaving and deinterleaving which are performed to the signal which the tuner shown in FIG. 1 receives. It is a block diagram which shows the structure of the demodulator shown by FIG. It is a timing chart which shows the influence which it has on the signal by the change of operation parameters, such as a tuner, by the control part shown by FIG. It is a block diagram which shows the structure of the control part shown by FIG. FIG. 6 is a timing chart showing errors that occur in a signal when another operation parameter is changed in addition to the operation parameter change shown in FIG. 5. FIG. 8 is a timing chart showing an error that occurs in a signal when another operation parameter change shown in FIG. 7 is changed. It is a flowchart which shows the whole flow of the operation parameter change control by the control part shown by FIG. It is a flowchart which shows the whole flow of the operation parameter change control which concerns on embodiment different from embodiment shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital demodulator 2 Tuner 3 Demodulator 4 Control part 21 RF amplifier part 22 Mixer part 23 VCO / PLL part 24 Filter part 25 IF amplifier part 36 Error correction part 41 Deinterleave part 51 Frequency deinterleave part 52 Time deinterleave part 53 Bit deinterleaving unit 54 Byte deinterleaving unit 61 Viterbi decoding unit 62 RS decoding unit 91 Error estimation unit 92 Correctability determination unit 93 Change determination unit 94 Operation parameter change unit 201 Portable information terminal Li Time interleave length Sb Symbols Sr, Si, Sd signal

Claims (38)

A plurality of circuit components constituting a tuner that performs channel selection processing on a reception signal that has been subjected to interleaving processing, and a demodulator that performs demodulation processing on the reception signal from the tuner;
Deinterleaving means for performing deinterleaving processing on the received signal from the tuner subjected to interleaving processing;
Error correcting means for correcting an error contained in the received signal subjected to deinterleaving by the deinterleaving means;
An operation parameter changing means for changing an operation parameter of at least one of the plurality of circuit components;
First change determining means for determining a first circuit component whose operation parameter is changed by the operation parameter changing means among the plurality of circuit components and a change amount of the operation parameter relating to the first circuit component;
The second circuit component whose operation parameter is changed by the operation parameter changing unit is determined among the plurality of circuit components, and the first parameter is more than the case where the operation parameter related to the second circuit component is not changed. An error that is included in the received signal when the operation parameter changing unit changes the operation parameter of the first circuit component determined by the change determining unit by the amount of change determined by the first change determining unit. Second change determining means for determining the amount of change of the operating parameter related to the second circuit component so that the amount of error included in the received signal corrected by the error correcting means is reduced;
The operation parameter changing unit changes the operation parameter of the first circuit component determined by the first change determining unit by the amount of change determined by the first change determining unit, and is generated in the received signal. Error estimation means for estimating the amount of virtual error
The operation parameter changing means changes the operation parameter of the first circuit component determined by the first change determining means by the amount of change determined by the first change determining means, and is included in the received signal. A first correctability determination unit that determines whether or not the error correction unit can correct the error based on the amount of the virtual error estimated by the error estimation unit;
The first and second change determination means determined by the first and second change determination means when the first correction possibility determination means determines that the error correction means cannot correct an error included in the received signal. Parameter change control means for controlling the operation parameter change means so that the operation parameters of the second circuit component are changed by the change amounts determined by the first and second change decision means, respectively. A digital demodulator. The first correction possibility determination means is
A first threshold value derivation means for deriving a threshold value of the amount of error that will be included in the received signal due to a change in operating parameters in the first circuit component;
When the error amount estimated by the error estimation means is equal to or less than the threshold value derived by the threshold value derivation means, the operation parameter of the first circuit component determined by the first change determination means is the first parameter. 2. The method according to claim 1, wherein the error correction unit can determine that the error included in the received signal can be corrected by the change of the operation parameter change unit by the change amount determined by the one change determination unit. The digital demodulator according to the description. The first threshold deriving means is built in the tuner;
The tuner receives from the demodulator at least one of a modulation scheme and a coding rate in the received signal;
3. The digital demodulator according to claim 2, wherein the first threshold deriving unit derives the threshold based on at least one of a modulation scheme and a coding rate in the received signal.   The second change determination means changes the operation parameter of the first circuit component determined by the first change determination means by the change amount determined by the first change determination means. Based on the amount of the virtual error estimated by the error estimation unit, the second circuit component and the second circuit component are corrected so that the error included in the received signal can be corrected by the error correction unit. 4. The digital demodulator according to claim 1, wherein an amount of change of an operation parameter related to the circuit component is determined. 5. The operation parameter changing means changes the operation parameters of the first and second circuit components determined by the first and second change determining means by the change amounts determined by the first and second change determining means, respectively. Second correction enable / disable judging means for judging whether or not the error correcting means can correct an error included in the received signal based on the amount of the virtual error estimated by the error estimating means. In addition,
When the error correction means cannot correct the error included in the received signal, the first correction possibility determination means determines that the error correction means can correct the error included in the received signal. When the second correction possibility determination means determines, the operation parameters of the first and second circuit components determined by the first and second change determination means are the first and second change determination means. 4. The digital demodulator according to claim 1, wherein the parameter change control unit controls the operation parameter change unit so that the change amount is changed by the determined change amount. The second correction possibility determination means is
Second threshold value derivation means for deriving a threshold value of the amount of error that will be included in the received signal due to a change in operating parameters in the first and second circuit components;
The operation parameter changing means changes the operation parameters of the first and second circuit components determined by the first and second change determining means by the change amounts determined by the first and second change determining means, respectively. And a total error amount deriving unit for deriving the amount of errors to be included in the received signal based on the virtual error amount estimated by the error estimating unit,
When the error amount derived by the total error amount deriving unit is less than or equal to the threshold derived by the second threshold deriving unit, the first and second change determining units determine the first and second change determining units. The error correction means detects an error that is included in the received signal when the operation parameter change means changes the operation parameter of the second circuit component by the change amount determined by the first and second change determination means. 6. The digital demodulator according to claim 5, wherein it is determined that correction is possible. The second threshold derivation means is built in the tuner;
The tuner receives from the demodulator at least one of a modulation scheme and a coding rate in the received signal;
The digital demodulator according to claim 6, wherein the second threshold deriving means derives the threshold based on at least one of a modulation scheme and a coding rate in the received signal.   When both of the first and second correction possibility determination means determine that the error correction means cannot correct an error included in the received signal, the first and second change determination means determine The parameter change control means controls the operation parameter change means so that neither of the operation parameters of the first and second circuit components is changed. The digital demodulator according to the description.   The second change determination unit determines a change amount related to an operation parameter of the second circuit component and the second circuit component so that an error correction capability of the error correction unit is improved. Item 9. The digital demodulator according to any one of Items 1 to 8. The second circuit component determined by the second change determining means is at least one of the plurality of circuit components constituting the tuner;
10. The second change determining means determines a change amount relating to an operation parameter of the second circuit component so that power consumption of the second circuit component is increased. The digital demodulator according to claim 1.   When the first correction possibility determination means determines that the error correction means cannot correct an error included in the received signal, the second circuit component determined by the second change determination means After the operation parameter change unit changes the operation parameter by the change amount determined by the second change determination unit, the operation parameter of the first circuit component determined by the first change determination unit is changed to the first parameter. 11. The digital demodulator according to claim 1, wherein the operation parameter changing unit changes the amount of change determined by the change determining unit. The deinterleaving process performed on the received signal by the deinterleaving means is a time deinterleaving process,
The time of interleaving length has elapsed since the operation parameter change unit changed the operation parameter of the second circuit component determined by the second change determination unit by the change amount determined by the second change determination unit. Then, the operation parameter changing unit changes the operation parameter of the first circuit component determined by the first change determining unit by the amount of change determined by the first change determining unit. The digital demodulator according to claim 11. The first change determination means from the time when the operation parameter change means changes the operation parameter of the second circuit component determined by the second change determination means by the change amount determined by the second change determination means. The operation parameter change means operates the second circuit component until the time when the operation parameter change means changes the operation parameter of the first circuit component determined by the amount of change determined by the first change determination means. Without changing the parameters
After the operation parameter changing means changes the operation parameter of the first circuit component, the operation parameter after the change according to the change amount determined by the second change determining means is changed to the operation parameter before the change. 13. The digital demodulator according to claim 11, wherein the operation parameter changing means returns the operation parameter of the circuit component. The deinterleaving process performed on the received signal by the deinterleaving means is a time deinterleaving process,
The first change determination from the time when the operation parameter change means changes the operation parameter of the second circuit component determined by the second change determination means by the change amount determined by the second change determination means. The operation parameter until the time when the time interleave length elapses after the operation parameter change unit changes the operation parameter of the first circuit component determined by the unit by the change amount determined by the first change determination unit. 14. The digital demodulator according to claim 13, wherein the parameter changing means does not change the operating parameter of the second circuit component.   The first change determining means determines a change amount relating to an operation parameter of the first circuit component and the first circuit component so that power consumption of the first circuit component is reduced. The digital demodulator according to claim 1. The change included in the received signal before the operation parameter changing unit changes the operation parameter of the first circuit component determined by the first change determining unit by the amount of change determined by the first change determining unit. An error amount deriving unit for deriving a previous error amount;
The first correction enable / disable determining means detects an error included in the received signal from the virtual error amount estimated by the error estimating means and the pre-change error amount derived by the error amount deriving means. 16. The digital demodulator according to claim 1, wherein it is determined whether or not the error correction unit can correct the error. The error amount deriving means is constructed in the demodulator, and the correction possibility judging means is constructed in the tuner, respectively.
The digital demodulator according to claim 16, wherein the tuner receives the pre-change error amount derived by the error amount deriving unit in the demodulator from the demodulator.   The error amount deriving means before the operation parameter changing means changes the operation parameter of the first circuit component determined by the first change determining means by the change amount determined by the first change determining means. 18. The digital demodulator according to claim 16, further comprising error rate deriving means for deriving an error rate of the received signal.   The error amount deriving means before the operation parameter changing means changes the operation parameter of the first circuit component determined by the first change determining means by the change amount determined by the first change determining means. 18. The digital demodulator according to claim 16, further comprising deviation derivation means for deriving a deviation from a specified value of the received signal constellation.   The error amount deriving means before the operation parameter changing means changes the operation parameter of the first circuit component determined by the first change determining means by the change amount determined by the first change determining means. 18. The digital demodulator according to claim 16, further comprising CN ratio deriving means for deriving a CN ratio of the received signal.   Occurrence of errors caused by the operation parameter changing means changing the operation parameter of the first circuit component determined by the first change determining means a plurality of times by the change amount determined by the first change determining means. 21. The operation parameter changing unit changes the operation parameter of the first circuit component so that the ranges do not overlap each other in the received signals after the deinterleaving process. The digital demodulator according to 1. The deinterleave process performed by the deinterleave means is a time deinterleave process,
23. The digital demodulator according to claim 21, wherein the operation parameter change means changes the operation parameter related to the first circuit component once or less within a time interleave length range.   The first change determining means determines the operation parameter of the first circuit component determined by the first change determining means at the timing when the first circuit component handles the tips of the plurality of unit signals included in the received signal. 23. The digital demodulator according to claim 1, wherein the operation parameter changing unit changes the determined change amount.   An error caused by the operation parameter changing unit changing the operation parameter of the first circuit component determined by the first change determining unit by the amount of change determined by the first change determining unit. 24. The digital demodulator according to claim 23, wherein a range of the received signal before time deinterleaving is within a range of one symbol. The tuner has an RF amplifier, a mixer, a filter, an IF amplifier, and a VCO / PLL.
The first or second circuit component determined by the first or second change determining means is any one of an RF amplifier, a mixer, a filter, an IF amplifier, and a VCO / PLL. The digital demodulator according to any one of 1 to 24.   The digital error according to any one of claims 1 to 25, wherein the error estimation means estimates the amount of the virtual error based on at least one of a modulation scheme and a coding rate in the received signal. Demodulator. The error estimation means is built in the tuner;
27. The digital demodulator according to claim 26, wherein the tuner receives at least one of a modulation scheme and a coding rate in a received signal from the demodulator. The first change determining means determines a change amount for a plurality of times of operation parameters in the first circuit component and the first circuit component;
The error estimation means is generated in the received signal by the operation parameter change means changing the operation parameter of the first circuit component a plurality of times in accordance with the change amount for the plurality of times determined by the first change determination means. 28. The digital demodulator according to claim 1, wherein a total amount of virtual errors to be estimated is estimated. Each of the first and second circuit components comprises a plurality of small circuit components,
2. The first and second change determining means determine an amount of change of an operation parameter in at least one of small circuit components constituting the first and second circuit components. The digital demodulator according to any one of to 28. Each of the first and second circuit components comprises a plurality of small circuit components,
If the error correction means cannot correct an error included in a received signal when an operation parameter is changed in m (m is a natural number) of the small circuit components constituting the second circuit component, When both the first and second correction enable / disable determining means determine, the change of the operation parameter in n (n is a natural number) greater than m of the small circuit components constituting the second circuit component 9. The digital demodulator according to claim 5, wherein the second change determining means determines an amount. A plurality of circuit components constituting a tuner that performs channel selection processing on a reception signal that has been subjected to interleaving processing, a demodulator that performs demodulation processing on a reception signal from the tuner, and a tuner from which the interleaving processing has been performed At least one of deinterleaving means for deinterleaving the received signal, error correcting means for correcting an error included in the received signal subjected to deinterleaving by the deinterleaving means, and at least one of the plurality of circuit components A control method of a digital demodulator comprising an operation parameter changing means for changing one operation parameter,
A first change determination step of determining a first circuit component whose operation parameter is changed by the operation parameter changing means among the plurality of circuit components and a change amount of the operation parameter related to the first circuit component;
The second circuit component whose operation parameter is changed by the operation parameter changing unit is determined among the plurality of circuit components, and the first parameter is more than the case where the operation parameter related to the second circuit component is not changed. An error that is included in the received signal when the operation parameter changing unit changes the operation parameter of the first circuit component determined in the change determination step by the change amount determined in the first change determination step. A second change determining step for determining a change amount of the operating parameter related to the second circuit component so that the amount of error included in the received signal after the error correction means corrects the error,
The operation parameter changing unit changes the operation parameter of the first circuit component determined in the first change determination step by the change amount determined in the first change determination step, and is generated in the received signal. An error estimation step for estimating the amount of virtual errors to be;
The operation parameter changing means changes the operation parameter of the first circuit component determined in the first change determination step by the change amount determined in the first change determination step, and is included in the received signal. A first correctability determination step for determining whether or not the error correction means can correct an error to be detected based on the amount of the virtual error estimated in the error estimation step;
The first and second change determination steps determined when the first correction determination step determines that the error correction means cannot correct an error included in the received signal. And a parameter change control step for controlling the operation parameter change means so that the operation parameters of the second circuit component are changed by the change amounts determined in the first and second change determination steps, respectively. A control method for a digital demodulator.   In the second change determination step, the operation parameter change means has the operation parameter of the first circuit component determined in the first change determination step by the change amount determined in the first change determination step. Based on the amount of the virtual error estimated in the error estimation step, the second circuit component and the error so that an error that is included in the received signal by the correction can be corrected by the error correction unit. 32. The method of controlling a digital demodulator according to claim 31, wherein an amount of change of an operation parameter related to the second circuit component is determined. The operating parameter changing means has the operating parameters of the first and second circuit components determined in the first and second change determining steps by the amount of change determined in the first and second change determining steps. A second correctability for determining whether or not the error correction means can correct an error included in the received signal by changing each based on the amount of the virtual error estimated in the error estimation step. A judgment step,
If the error correction means cannot correct the error that will be included in the received signal, it is determined in the first correction possibility determination step, and the error correction means can correct the error that will be included in the received signal. When determined in the second correctability determination step, the operating parameters of the first and second circuit components determined in the first and second change determination steps are the first and second changes. 32. The digital demodulator according to claim 31, wherein the operation parameter changing means is controlled in the parameter change control step so as to be changed by the change amount determined in the determining step. The deinterleaving process performed on the received signal by the deinterleaving means is a time deinterleaving process,
The time of the interleave length after the operation parameter changing means changes the operation parameter of the second circuit component determined in the second change determination step by the change amount determined in the second change determination step. After the time elapses, the operation parameter changing means changes the operation parameter of the first circuit component determined in the first change determination step by the change amount determined in the first change determination step. 32. The method of controlling a digital demodulator according to claim 31. The deinterleaving process performed on the received signal by the deinterleaving means is a time deinterleaving process,
From the time when the operation parameter changing means changes the operation parameter of the second circuit component determined in the second change determination step by the change amount determined in the second change determination step, the first circuit component is changed. The time when the time interleave length elapses after the operation parameter changing means changes the operation parameter of the first circuit component determined in the change determination step by the change amount determined in the first change determination step. Until the operation parameter changing means does not change the operation parameter of the second circuit component,
After the operation parameter changing means changes the operation parameter of the first circuit component, the operation parameter after the change according to the change amount determined in the second change determining step is changed to the operation parameter before the change. 35. The method of controlling a digital demodulator according to claim 34, wherein the operation parameter changing means returns the operation parameter of the circuit component. A program used in a digital demodulator comprising a tuner that performs channel selection processing on a reception signal that has been subjected to interleaving processing, and a plurality of circuit components that constitute a demodulator that performs demodulation processing on the reception signal from the tuner Because
Deinterleaving means for deinterleaving the received signal from the tuner subjected to interleaving processing, and error correcting means for correcting an error contained in the received signal subjected to deinterleaving by the deinterleaving means,
An operation parameter changing means for changing an operation parameter of at least one of the plurality of circuit components;
A first change determination means for determining a change amount of an operation parameter related to the first circuit component and the first circuit component of which the operation parameter is changed by the operation parameter change means among the plurality of circuit components;
The second circuit component whose operation parameter is changed by the operation parameter changing unit is determined among the plurality of circuit components, and the first parameter is more than the case where the operation parameter related to the second circuit component is not changed. An error that is included in the received signal when the operation parameter changing unit changes the operation parameter of the first circuit component determined by the change determining unit by the amount of change determined by the first change determining unit. Second change determining means for determining a change amount of the operating parameter related to the second circuit component so that the amount of error included in the received signal after correction by the error correcting means is reduced;
The operation parameter changing unit changes the operation parameter of the first circuit component determined by the first change determining unit by the amount of change determined by the first change determining unit, and is generated in the received signal. An error estimation means for estimating the amount of virtual error,
The operation parameter changing means changes the operation parameter of the first circuit component determined by the first change determining means by the amount of change determined by the first change determining means, and is included in the received signal. An error correction means for determining whether or not the error correction means can correct the error based on the amount of the virtual error estimated by the error estimation means; and
The first and second change determination means determined by the first and second change determination means when the first correction possibility determination means determines that the error correction means cannot correct an error included in the received signal. The digital demodulator functions as parameter change control means for controlling the operation parameter change means so that the operation parameters of the second circuit component are changed by the change amounts determined by the first and second change determination means, respectively. A program for a digital demodulator, characterized by:   A recording medium on which the program for a digital demodulator according to claim 36 is recorded. A digital demodulator according to any one of claims 1 to 30 is provided,
A digital reception device that performs reproduction processing of at least one of characters, images, sounds, and data based on a reception signal demodulated by the digital demodulation device.

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