JP2008245182A - Tunable receiver with automatic frequency correction function - Google Patents

Abstract

In a portable wireless terminal, in order to improve user convenience, it is desired to receive broadcast radio waves or wireless communication using a built-in antenna.
A receiving channel is changed in a receiving device including a tuner, a tunable antenna, and a storage unit storing a control value (table) of a variable capacity unit that maximizes reception sensitivity for each receiving channel. In this case, the optimum receiving sensitivity can always be obtained by reading out the control voltage value that maximizes the receiving sensitivity of the receiving channel from the storage means based on the receiving channel information and updating it to the control voltage value.
[Selection] Figure 9

Description

  The present invention relates to a portable wireless terminal such as a mobile phone, a PDA, a notebook computer, and a game machine, an antenna module built in a wireless device, and a receiving device equipped with the antenna module. In particular, the present invention relates to an antenna module characterized in that an antenna frequency characteristic is varied according to a reception frequency channel in a digital broadcast receiving apparatus, and a receiving apparatus including the antenna module.

  Patent Document 1 proposes to use a monopole antenna as a prior art antenna that is applied to a radio system that receives radio waves having a frequency lower than that of a mobile phone, such as terrestrial analog broadcasting and terrestrial digital broadcasting. Yes.

  Such an antenna has a wide band and can correspond to the entire frequency band used by the system, but the wavelength of the radio wave to be received by this antenna is, for example, 64 cm in the case of Japanese terrestrial digital television broadcasting, There is a problem that it is difficult to incorporate into a mobile terminal such as a current mobile phone, PDA, or receiver having a maximum dimension of about 20 cm.

  Currently, mobile wireless terminals are becoming more sophisticated. For example, in mobile phones, in addition to telephone functions, it is conceivable that reception functions such as television broadcasting and radio broadcasting will be combined in the future. Each of these broadcasting systems is assigned a different frequency band, and uses a channel obtained by frequency-dividing these bands. For example, a wide frequency band of 470 MHz to 770 MHz UHF band is allocated to Japanese terrestrial digital television broadcasting, and a band obtained by dividing this band into 6 MHz intervals is allocated to each broadcasting station. For viewing, the viewer needs to select a desired frequency.

  It is desirable to avoid receiving all of the wide frequency band used by each wireless system with one antenna from the viewpoint of interference wave suppression, and the size is sufficiently smaller than the wavelength of the electromagnetic wave to be adapted (1/10 or less). ) For antennas, from the standpoint of antenna sensitivity, it is expected that performance will be improved by narrowing the reception frequency band. For the former reason, in order to prevent reception of signals from other wireless systems that are disturbing waves for the television system, unnecessary frequency channels other than the frequency channel desired to be viewed are provided in the tracking filter circuit after the antenna. There is a case in which a mechanism for removal is provided.

  On the other hand, since portable wireless terminals are required to be downsized from the viewpoint of improving portability, downsizing of each antenna is also required. In such a background, Patent Document 2 discloses a wireless terminal using a so-called tuned antenna, characterized in that the impedance matching center frequency of the tuned antenna is controlled in accordance with the communication frequency.

JP 2001-251131 A JP 2003-298341 A

  When such a tuned antenna having a sufficiently small size compared to the wavelength of the received radio wave is used and the antenna is built in, the antenna has a very high Q compared to an external antenna such as a rod antenna. It has become. For this reason, when it is built in a device such as a mobile phone, the resonance frequency changes by several MHz just by approaching the part containing the antenna. An antenna with a very high Q has a narrow band and a large reactive power accumulated around the antenna. Therefore, the resonance frequency slightly changes when a hand approaches the vicinity of the antenna. It is conceivable that reception characteristics deteriorate.

  Further, since the tuning antenna includes variable capacitance means as its constituent elements, the characteristic values of components constituting the tuning antenna such as the variable capacitance means (variable capacitance diode) vary during mass production. Inevitable. Therefore, when receiving devices are mass-produced with inexpensive parts with large variations in performance, it is difficult to set the receiving frequency to a constant value in any receiving device, and the yield of receiving devices may be deteriorated. .

  The object of the present invention is to automatically control the resonance frequency of a high-Q narrow-band sensitive antenna so that radio waves in all bands used by systems such as terrestrial analog broadcasting and terrestrial digital broadcasting can be received. Another object of the present invention is to provide a receiving circuit including a small antenna that can be built in a portable wireless terminal such as a cellular phone or a PDA. Furthermore, at that time, the reception characteristics including the small antenna required for the mobile terminal can be reduced without touching the housing and deteriorating the reception characteristics, or causing the product yield to deteriorate due to variations in each component. It is to provide a circuit.

  In order to solve the above problems, in the present invention, a tuner having a function capable of outputting a control signal related to reception sensitivity is prepared in addition to a tuned antenna whose resonance frequency is controlled by a variable capacitance means. Using a control circuit that processes signals and controls the variable capacitance means, the variable capacitance means is automatically controlled by this control circuit so as to optimize the reception sensitivity. Furthermore, even if the reception channel is changed, the table in the storage means is stored even if the reception channel is changed by storing the control value (table) of the variable capacity means that maximizes the reception sensitivity for each reception channel in the storage means inside the microcontroller. By referring to the variable capacity means, the variable capacity means can be automatically controlled so that the reception sensitivity is instantaneously maximized.

  Further, for example, in the case of a foldable mobile phone, the control value of the variable capacity means must be changed even in the same reception channel depending on the use situation (open state or folded state). In the case of such a receiving device, by storing the control value (table) of the variable capacity means that maximizes the receiving sensitivity of each receiving channel according to the use status of the device, in the storage means, The variable capacitance means can be automatically controlled so that the reception sensitivity is instantaneously maximized.

  At this time, the reception sensitivity signal output from the tuner is related only to the reception sensitivity of the signal in the frequency band (reception channel) to be received selected outside the reception device, and the reception of the signal in the frequency band not selected. It is not related to sensitivity. For example, when receiving 14ch, adjacent 13ch and 15ch signals may be input to the tuner. However, according to the present invention, the reception sensitivity signal is processed only by the 14ch received signal. Output reception sensitivity signal. This can be realized by using signal processing after frequency selection in the tuner. In this way, the sensitivity of the tunable antenna is optimized only for the desired reception channel. In addition, the resonance frequency of the tunable antenna is controlled simultaneously with the tuning operation of the tuner. If the reception sensitivity signal has a characteristic of monotonously increasing or monotonously decreasing with respect to the reception sensitivity, the control algorithm may be simple. In other words, if the reception sensitivity increases when the reception sensitivity signal is monotonously increased, the reception sensitivity signal is increased monotonically as it is, and if the reception sensitivity is decreased, the reception sensitivity signal is decreased monotonously. Therefore, an algorithm for controlling the reception sensitivity to be large may be simple. Further, when the reception sensitivity is sufficiently high, there is no need to change.

  On the other hand, a control circuit that processes the reception sensitivity signal and controls the variable capacitance means includes at least one direct-current control voltage output, and controls the variable capacitance means by this control voltage. For example, if a variable capacitance diode is used for the variable capacitance means, the reverse bias voltage of the variable capacitance diode can be used as the control voltage.

  As shown above, by providing a control circuit that outputs the reception sensitivity signal from the tuner and controls the variable capacitance means, reading the reception sensitivity signal and sequentially changing the control voltage, the reception frequency band, that is, A receiving channel can be selected.

  Further, as a control circuit for processing the reception sensitivity signal and controlling the variable capacitance means, a microcontroller, a PWM (Pulse Width Modulation) circuit, and a smoothing circuit including a resistance element and a capacitance element may be used. Further, an A / D (Analog / Digital) converter may be used for the control circuit that processes the reception sensitivity signal and controls the variable capacitance means.

  Specifically, as the control performed by the microcontroller, the microcontroller monitors the reception sensitivity signal, and when the reception sensitivity falls below a certain value, the control voltage for controlling the variable capacitance means is sequentially changed to obtain the reception sensitivity. There is a method of temporarily storing a control voltage at which the maximum is received and automatically setting the control voltage at which the reception sensitivity is maximized after the sequential change is completed.

  Further, if the control voltage for controlling the variable capacitance means is sequentially changed by the microcontroller and the reception sensitivity increases with respect to the sequential change of the control voltage, the sequential change of the control voltage is continued in the same direction, and the reception sensitivity is increased. If it decreases, a method of automatically setting the control voltage that maximizes the reception sensitivity by reversing the direction of the sequential change of the control voltage and repeating this may be used.

  In addition, the control signal related to the reception sensitivity is monitored by the microcontroller, and when the reception sensitivity falls below a certain value, the amount of change of the control voltage for controlling the variable capacity means is increased and the reception sensitivity is increased. The control voltage can be automatically set at a high speed at a maximum reception sensitivity by decreasing the amount of sequential change of the control voltage in accordance with the increase and repeating this.

  Furthermore, by monitoring the reception sensitivity signal, measure how many times the reception sensitivity has been reduced to a certain value or less, and measure the number of times the reception sensitivity has decreased to a certain value. Only when it is obtained, there is a method of increasing the amount of change of the control voltage for controlling the sensitivity variable capacitance means to be increased and performing the change of the variable capacitance only when necessary.

  According to the present invention, it is possible to realize a tunable antenna that is small, highly sensitive, and whose resonance frequency can be controlled by the variable capacitance means. It is possible to realize a portable wireless terminal capable of receiving radio waves having a frequency lower than that of broadcasting or terrestrial digital broadcasting. At this time, if it is a conventional receiving circuit, the receiving sensitivity may deteriorate when the hand approaches the antenna built-in portion. However, according to the present invention, the receiving sensitivity is automatically optimized. Therefore, the reception sensitivity is hardly deteriorated.

  Further, according to the present invention, even if the components constituting the receiving circuit have characteristics that vary to some extent during mass production, the receiving frequency is adjusted so that the receiving sensitivity is optimized by the automatic correction function of the receiving circuit itself. Therefore, there is no need to consider component variations. For this reason, the yield of the receiving circuit is high and the cost can be suppressed.

  Still further, according to the present invention, the memory means is provided in the microcontroller, and the control value (table) of the variable capacity means that maximizes the reception sensitivity of each receiving channel is stored in the memory means according to the use status of the apparatus. By making it possible to refer to the table in the storage means when the usage status of the apparatus and / or the reception channel is changed, the variable capacity means can be automatically controlled based on the table. It is possible to omit the time for adjusting the variable capacitance means while finely adjusting the variable capacity means so as to obtain the optimum reception sensitivity.

  Furthermore, as another effect of the present invention, the tunable operation of the antenna in various states can be performed by the microcontroller. For example, the case can be opened and closed when using a device such as a folded mobile phone, a laptop computer, or a game machine. As a result, it is possible to correct the reception frequency when the environment around the antenna changes and the antenna characteristics change.

  The technical point of the present invention is to automatically control the resonance frequency of the antenna using the reception sensitivity signal output from the tuner, thereby stabilizing the reception characteristics of the reception device and improving the yield in mass production.

  Hereinafter, first, a method for obtaining a control value (table) of the variable capacity means for storing in the storage means in advance will be described with reference to the drawings.

  An example of a method for acquiring the control value (table) of the variable capacity means for storing in advance in the first storage means of the present invention will be described with reference to FIG. 1, FIG. 2, FIG. 3 and FIG. FIG. 1 is a diagram showing a configuration of a first acquisition example in an antenna module according to the present invention and a receiving circuit connected to the antenna module, and FIG. 2 is a flowchart of an automatic control algorithm of the acquisition example. The tunable antenna 1 includes a wave receiving element 2 and a tuning circuit 3, and the tuning circuit 3 includes a variable capacitance diode 4, a capacitor 5, and a resistor 6. The tunable antenna 1 is provided with a control signal input terminal 7 and a reception signal output terminal 8. The control circuit 9 includes a microcontroller 10 and a smoothing circuit 11. The microcontroller 10 includes a PWM circuit, an AD converter, and a memory. The microcontroller 10 includes a PWM output terminal 12 and an AD converter input terminal 13. A smoothing circuit 11 is connected to the PWM output terminal 12, and a tuner is connected to the end. It is connected to the control signal input terminal 7 of the bull antenna. A reception sensitivity voltage output terminal 15 of the tuner 14 is connected to the AD converter input terminal 13. The tuner 14 has a reception signal input terminal 16 and is connected to the reception signal output terminal 8 of the tunable antenna 1. Further, the tuner 14 is provided with a channel data input terminal 18 for receiving a channel to be received from the outside of the receiving circuit, here, the antenna module according to the present invention, and the main control unit 17 of a wireless device equipped with the antenna module. .

  According to this acquisition example, first, channel information received from the main control unit 17 outside the receiving circuit is input to the tuner 14 through the channel data input terminal 18. Based on the input channel data, the tuner 14 demodulates the received signal of the desired channel supplied from the tunable antenna 1. At this time, a voltage associated with the reception sensitivity is output to the reception sensitivity voltage output terminal 15 in accordance with the reception signal input to the reception signal input terminal 16 of the tuner 14. In this acquisition example, a voltage that increases in proportion to the received power of the selected channel is output. When the tuner 14 outputs the reception sensitivity voltage to the AD converter input terminal 13 of the microcontroller 10 in the control circuit 9, the reception sensitivity voltage is AD-converted and a certain process inside the microcontroller 10 is started. In this acquisition example, when it is determined that the reception sensitivity voltage is smaller than a certain set value, the PWM waveform output to the PWM output terminal 12 of the microcontroller 10 is sequentially changed, and the control voltage output through the smoothing circuit 11 is changed. . As a result, the DC voltage input to the control signal input terminal 7 of the tuning circuit 3 changes, and the reverse voltage applied to the variable capacitance diode 4 changes, thereby changing the capacitance value and changing the resonance frequency of the antenna. It is changed (FIG. 3 (A)). The resonant frequency of the antenna is sequentially changed, and each time the tuner 14 demodulates the reception signal output from the tunable antenna 1 and updates the reception sensitivity voltage. When the reception sensitivity voltage reaches the maximum value (FIG. 3B), the microcontroller 10 stores the control voltage at that time in the internal memory, and after the sequential change of the reception frequency is completed (FIG. 3C). ), The PWM output of the microcontroller is controlled so that the control circuit 9 outputs the control voltage stored in the internal memory at which the reception sensitivity becomes the maximum value (FIG. 3D). An example of the temporal change of the reception sensitivity voltage and the control voltage at this time is shown in FIG. By writing a program to the built-in flash memory of the microcontroller 10 and executing these series of controls, it is possible to receive radio waves having a required reception frequency.

  Further, when the vicinity of the tunable antenna 1 of the receiving apparatus is touched with a hand, the resonance frequency of the antenna generally changes and often decreases. At this time, since a signal with degraded sensitivity is output to the reception signal output terminal of the tunable antenna 1, a voltage lower than that before touching is output to the reception sensitivity voltage output terminal 15 of the tuner 14. When the AD converter input terminal 13 of the microcontroller 10 detects this, the same program is executed to determine again the control voltage that can be received with the maximum sensitivity. As a result, the control voltage is updated to an optimum control voltage in a state where the hand is touched, and reception is continued. For this reason, with the receiving circuit of the present invention, even if a hand touches the tunable antenna, deterioration of receiving sensitivity is suppressed.

  Even when the channel to be received is changed, the reception sensitivity voltage is lowered, so that the same program is executed to automatically update the frequency to a desired reception channel. This is because the reception sensitivity voltage is output according to the reception sensitivity of only the reception signal of the channel selected and demodulated by the tuner 14. Furthermore, even if the control voltage of each individual differs due to manufacturing variations during mass production, the program of the microcontroller 10 corrects the reception voltage, so that the reception characteristics are not affected at all.

  FIG. 8 shows a configuration of a receiving apparatus using a conventional tunable antenna. 1 is different from the configuration of the actual acquisition example of the present invention of FIG. 1 in that a DA converter 19 is provided in place of the control circuit 9, and channel information from the main control unit 17 is input to the DA converter 19 as DA converter channel data input. Obtained from terminal 20. The acquired channel information is digital information previously written in the memory in the main control unit 17 and associated with each channel. The DA information is converted into an analog control voltage by the DA converter 19 to control the tunable antenna 1. It is to be supplied to the signal terminal 7. In this prior art, even if the environment around the tunable antenna 1 changes and the characteristics of the tunable antenna 1 change, and as a result, the reception sensitivity of the tuner 14 deteriorates, the deterioration cannot be corrected. . On the other hand, according to the configuration of one acquisition example of the present invention shown in FIG. 1, even if there is a factor that causes the reception sensitivity of the tunable antenna 1 to deteriorate, such as hand influences and mass production variations, As a result of automatic control by the controller 10, good reception characteristics can always be realized, and as a result, a highly sensitive receiving circuit can be realized.

  An example of a method for acquiring the control value (table) of the variable capacity means for storing in advance in the second storage means of the present invention will be described with reference to FIGS. FIG. 4 is a flowchart of an automatic control algorithm executed by the microcontroller 10 in the present invention. FIG. 5 is a diagram showing a change in the control voltage with time and the relationship between the control voltage and the reception sensitivity voltage in the present invention. In the present invention, the same circuit configuration of FIG. However, the automatic control program executed by the microcontroller 10 executes an algorithm based on the flowchart shown in FIG. As shown in FIG. 4, the reception sensitivity voltage output from the tuner 14 is read into the AD converter input terminal 13 of the microcontroller 10, and then the PWM output output from the PWM output terminal 12 of the microcontroller 10 is changed to change the control signal. By changing the voltage, the voltage applied to the variable capacitance diode 4 changes, and the resonance frequency changes. As a result, the received signal of the tunable antenna changes and the received signal received by the tuner 14 also changes. At this time, the microcontroller 10 reads the reception sensitivity voltage read by the updated AD converter input terminal, and evaluates whether the value is increasing or decreasing. If the reception sensitivity voltage is decreasing, the direction in which the control voltage changes is reversed, that is, when the control voltage is increasing, it is changed to decreasing, and when it is decreasing, it is changed to increasing. By repeating this, control is automatically performed so that the control voltage that maximizes the reception sensitivity voltage is applied to the control voltage input terminal 7 of the tunable antenna 1. If it demonstrates in FIG. 5, it will change to the control voltage in which the maximum receiving sensitivity voltage is obtained, moving to A-> B-> C-> D-> E-> F-> G as shown in the figure.

  According to the present invention, compared with the acquisition example 1, since the control voltage changes in both positive and negative directions, the time required to reach the optimum control voltage is faster. Therefore, even if the reception sensitivity deteriorates, the reception sensitivity can be recovered at high speed.

  Also, when the reception sensitivity voltage is low and the optimum control voltage is still small, the amount of change in the control voltage is increased and the direction in which the control voltage changes is reversed or the reception sensitivity voltage increases. By reducing the change amount of the control voltage, the optimum control voltage can be reached at a higher speed.

  An example of a method for acquiring the control value (table) of the variable capacity means for storing in advance in the third storage means of the present invention will be described with reference to FIGS. FIG. 6 is a flowchart of an automatic control algorithm executed by the microcontroller 10 in the present invention. FIG. 7 is a diagram showing the time change of the reception sensitivity voltage in the present invention. In the present invention, the same circuit configuration of FIG. However, the automatic control program executed by the microcontroller 10 executes an algorithm based on the flowchart shown in FIG. As shown in FIG. 6 or FIG. 7A, the microcontroller 10 reads the reception sensitivity voltage output from the tuner 14 at the AD converter input terminal 13, and the value is equal to or more than the reference value twice or more in three times. The reception sensitivity voltage is continuously monitored without changing the control voltage. On the other hand, as shown in FIGS. 6 and 7B, when the reception sensitivity voltage exceeds the reference value only once in 3 times, the PWM output output from the PWM output terminal 12 of the microcontroller 10 is changed. Then, the voltage applied to the variable capacitance diode 4 is changed, the resonance frequency is changed, and control for searching for the optimum reception state of the tunable antenna is started.

  In acquisition examples 1 and 2, the microcontroller 10 immediately responds to a sudden decrease in the reception sensitivity voltage, and starts an algorithm for searching for the optimum control voltage. While the algorithm for searching for the optimum control voltage is being executed, a temporary decrease in sensitivity is inevitable. According to this acquisition example, compared to the acquisition examples 1 and 2, the microcontroller 10 does not immediately start an algorithm for searching for the optimum control voltage with respect to the sudden decrease in the reception sensitivity voltage. Deterioration time can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 9 shows a configuration in which an EEPROM 21 as a storage unit is further added to the inside of the microcontroller 10 in addition to the circuit configuration of the control value acquisition example 1 (FIG. 1) of the variable capacitance unit. The automatic control program executed by the microcontroller of this embodiment executes an algorithm based on the flowchart shown in FIG.

  The control voltage value of the variable capacitance means that maximizes the reception sensitivity of each reception channel (frequency band to be received) varies from device to device due to variations even in the same type. Therefore, the EEPROM 21 is built in the microcontroller 10, and optimization data of the control voltage value that maximizes the reception sensitivity of each reception channel is stored in the EEPROM 21 for each device, and the reception channel is changed. In this case, this data is referred to. By doing so, the control voltage value to be set can be instantly determined, so that the reception sensitivity can be maximized immediately. Hereinafter, this example will be described in detail.

  First, the control voltage value list data (table) that maximizes the reception sensitivity of each reception channel in each individual device is acquired by the automatic correction function in any of acquisition examples 1 to 3, and the table is written to the EEPROM 21. Leave in. As a result, when the reception channel is changed as shown in the flowchart of FIG. 10, the control voltage value that maximizes the reception sensitivity of the reception channel is read from the EEPROM 21 based on the reception channel information, and the control voltage is read. By updating to the value, the optimum reception sensitivity can be obtained. Thereafter, if necessary, the control voltage value is finely adjusted using any one of the methods 1 to 3 in which the control value of the variable capacitance means is acquired, so that a larger and more stable reception sensitivity can be obtained.

  As described above, the tunable receiver with an automatic frequency correction function according to the present embodiment stores the control voltage value table in which the reception sensitivity of each reception channel is maximized in advance in the EEPROM 21, so that the second and subsequent times. When the reception channel is changed, the control voltage value that maximizes the reception sensitivity can be read from the EEPROM 21 based on the reception channel information, and can be immediately updated to the control voltage value. By doing this, it is possible to omit the time to adjust while adjusting the control voltage value so as to maximize the reception sensitivity, so that it is possible to view images without stress when receiving television. Become.

  A second embodiment of the present invention will be described with reference to FIGS. 9 uses the same circuit configuration as that of the first embodiment, and further stores control voltage value data in which the reception sensitivity of each reception channel is maximized in the EEPROM 21 according to the usage pattern of the device. The automatic control program executed by the microcontroller of this embodiment executes an algorithm based on the flowchart shown in FIG.

  First, depending on the usage pattern of each device (for example, when the foldable mobile phone is opened or closed, the control voltage value at which the reception sensitivity is maximized differs). The list data (table) of the control voltage value that maximizes is acquired by the automatic correction function in any one of the acquisition examples 1 to 3, and the table is stored in the EEPROM 21. As a result, as shown in the flowchart of FIG. 11, first, the presence / absence of change of the reception channel and the usage pattern of the device are confirmed, and the reception channel and the usage status pattern of the device are read from the EEPROM 21 based on the information. Accordingly, the optimum reception sensitivity can be obtained by reading out the control voltage value that maximizes the reception sensitivity and updating it to the control voltage value. Thereafter, a finer and more stable reception sensitivity can be obtained by finely adjusting the control voltage value as necessary using any one of the methods 1 to 3 in which the control value of the variable capacitance means is acquired.

  As described above, the tunable receiver with an automatic frequency correction function according to the present embodiment stores in advance in the EEPROM 21 a table of control voltage values that maximizes the reception sensitivity of each reception channel in accordance with the usage pattern of the device. As a result, when the reception channel and / or device usage pattern is changed after the second time, the control voltage value that maximizes the reception sensitivity is read from the EEPROM 21 based on the information, and the control voltage By immediately updating to the value, the optimum reception sensitivity can be obtained, so the time to adjust while finely adjusting the control voltage value to maximize the reception sensitivity can be omitted. , You will be able to view images without stress.

  In the flowchart of FIG. 11, it is configured to first check whether the reception channel is changed and then check the usage pattern of the device. However, in reverse order, first, the usage status pattern of the device is displayed. It may be configured to check and then check whether there is a change in the reception channel.

Configuration of a receiving circuit according to an example of a method for acquiring a control value (table) of variable capacitance means for storing in advance in the first storage means The flowchart showing the operation | movement which becomes an example of the acquisition method of the control value (table) of the variable capacity | capacitance means for making it memorize | store beforehand in a 1st memory | storage means. Time variation of control voltage and reception sensitivity voltage representing an operation as an example of a method for acquiring a control value (table) of a variable capacity means for storing in advance in the first storage means The flowchart showing the operation | movement which becomes an example of the acquisition method of the control value (table) of the variable capacity | capacitance means for making it memorize | store beforehand in a 2nd memory | storage means. Relationship between time variation of control voltage, control voltage, and reception sensitivity voltage, representing operation as an example of a method for acquiring a control value (table) of variable capacitance means for storing in advance in the second storage means The flowchart showing the operation | movement which becomes an example of the acquisition method of the control value (table) of the variable capacity | capacitance means for making it memorize | store beforehand in a 3rd memory | storage means. Time variation of reception sensitivity voltage representing an operation as an example of a method of acquiring a control value (table) of variable capacitance means for pre-stored in the third storage means Configuration of conventional tunable antenna and its receiving circuit Configuration of receiving circuit according to first and second embodiments The flowchart showing the operation according to the first embodiment. The flowchart showing the operation according to the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tunable antenna 2 Receiver element 3 Tuning circuit 4 Variable capacity diode 5 Capacitance 6 Resistance 7 Control signal input terminal 8 Reception signal output terminal 9 Control circuit 10 Microcontroller 11 Smoothing circuit 12 PWM output terminal 13 AD converter input terminal 14 Tuner 15 Reception sensitivity signal output terminal 16 Reception signal input terminal 17 Main control unit 18 Channel data input terminal 19 DA converter 20 DA converter channel data input terminal

Claims (2)

A tunable antenna whose resonance frequency is controlled by a variable capacitance means, a tuner having a function capable of outputting a reception sensitivity signal that is a control signal related to reception sensitivity, and processing the reception sensitivity signal to control the variable capacitance means In the tunable receiver with an automatic frequency correction function, the variable capacitance means is automatically controlled so that the reception sensitivity is optimized by the control circuit.
A control value (table) of the variable capacitance means that maximizes the reception sensitivity for each frequency band to be received is acquired in advance, and the table is stored in the storage means provided in the control circuit for reception. When the power frequency band is changed, the control value of the variable capacity means that maximizes the reception sensitivity in the changed frequency band is obtained from the table stored in the storage means, and the control is performed based on the control value. A tunable receiver with an automatic frequency correction function, wherein the variable capacitance means is automatically controlled by a circuit. A tunable antenna whose resonance frequency is controlled by a variable capacitance means, a tuner having a function capable of outputting a reception sensitivity signal that is a control signal related to reception sensitivity, and processing the reception sensitivity signal to control the variable capacitance means In the tunable receiver with an automatic frequency correction function, the variable capacitance means is automatically controlled so that the reception sensitivity is optimized by the control circuit.
A control value (table) of the variable capacitance means that maximizes reception sensitivity is obtained in advance for each frequency band to be received in accordance with the usage pattern of the receiving apparatus, and the table is stored in the storage means provided in the control circuit. By storing the frequency band to be received and / or the frequency band after the change from the table stored in the storage means when the usage pattern of the receiving device is changed, and / or A control value of the variable capacitance means having a maximum reception sensitivity in the usage pattern of the receiving device is acquired, and the variable capacitance means is automatically controlled by the control circuit based on the control value. Tunable receiver with automatic frequency correction function.

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