JP2007201855A - Digital broadcast retransmission device - Google Patents

Abstract

A digital broadcast retransmission apparatus capable of avoiding a wraparound phenomenon is provided.
A signal processing unit includes a signal branching means, a signal attenuating means for attenuating the output of the signal branching means by a predetermined level, and a signal amplifying means for amplifying the output of the signal attenuating means to a predetermined level. And a channel selection / demodulation unit 12 for selectively selecting a signal of a predetermined broadcast channel from a branch output of the signal branching unit and demodulating predetermined data from the signal of the broadcast channel, and The bit error rate is calculated from predetermined data demodulated by the demodulating means, and the bit error rate obtained from the calculation result is compared with a predetermined reference value of the bit error rate provided in advance, and the signal amplifying means And a monitoring / controlling unit 13 for controlling the attenuation amount of the signal attenuating unit so that the output after amplification by the signal changes from the predetermined level by a predetermined amount. .

[Selection] Figure 1

Description

The present invention relates to a digital broadcast retransmission apparatus at a relay station that retransmits terrestrial digital broadcasts, and more particularly, a digital broadcast retransmission apparatus that detects and prevents interference due to wraparound between a reception antenna and a transmission antenna provided in the retransmission apparatus. About.

In terrestrial digital broadcasting, it is considered to retransmit by SFN (Single Frequency Network) as a retransmitting device to a radio interference area. In this case, if the radio wave radiated from the transmitting antenna provided in the retransmitting device wraps around the receiving antenna provided in the retransmitting device and receiving the radio wave from the master station, the signal may deteriorate or in the worst case. The re-transmission device may oscillate. To cope with this, the physical distance between the receiving antenna and the transmitting antenna is maintained, the wraparound phenomenon is electrically canceled, the characteristics of the receiving antenna are improved, etc. The method has been taken.
For example, first frequency conversion means for frequency conversion to an intermediate frequency for signal processing, intermediate frequency signal processing means for signal processing the output of the first frequency conversion means, and output of the intermediate frequency signal processing means A second frequency converting means for converting the frequency into the frequency band of the received digital broadcast; and a local signal generating means for generating a signal for frequency conversion of the first frequency converting means and the second frequency converting means. In this conventional retransmission apparatus, the purpose of use is to retransmit to a radio interference area, the target area is small, and the output power of the retransmission apparatus can be reduced. Therefore, in order to avoid the wraparound phenomenon that occurs between the reception antenna and the transmission antenna, the wraparound phenomenon is avoided by physically separating the reception antenna and the transmission antenna. It had been made.
(For example, see Patent Document 1)
There has also been proposed a single frequency broadcast wave repeater configured to compensate for a sneak component using a pilot signal.
(For example, see Patent Document 2)

JP 2003-060997 A JP 2004-328286 A

However, according to the digital broadcast retransmitting apparatus as shown in Patent Document 1, in order to avoid the wraparound phenomenon that occurs between the receiving antenna and the transmitting antenna, the receiving antenna and the transmitting antenna are physically separated. However, if it is too far away, it is disadvantageous in terms of cost because it is necessary to secure the installation location and consider the support brackets. Furthermore, during operation after the digital broadcast retransmission device is installed, if a wraparound phenomenon occurs due to changes in the device characteristics or environmental changes due to buildings or trees in the surrounding area, There was a problem that reception interference occurred in the entire radio interference area.
In addition, in a relay device that compensates the sneak component using a pilot signal as shown as a representative example in Patent Document 2, a circuit is complicated because a pilot signal generator and a canceller for compensating the sneak component are required. As a result, there is a problem that the cost of the retransmission apparatus is high.
Therefore, in this application, it was made to solve these problems.
The purpose is to provide an inexpensive and high-performance digital broadcast retransmission apparatus suitable for digital broadcast retransmission.
Another object is to provide a digital broadcast re-transmission device that has a simple configuration and is resistant to sneak current.
Another object is to provide a digital broadcast retransmission apparatus capable of detecting and preventing interference due to wraparound.

In order to solve the above-mentioned problems, the invention of claim 1 is configured to receive a digital broadcast wave by a receiving antenna and retransmit the signal from the receiving antenna as a digital broadcast wave from the transmitting antenna by performing predetermined signal processing. In the digital broadcast retransmitting apparatus configured as above, at least a signal branching means for passing a signal received by the receiving antenna and branching a part of the signal, and a signal for attenuating the output of the signal branching means by a predetermined level A signal processing unit comprising an attenuating unit, a signal amplifying unit for amplifying the output of the signal attenuating unit to a predetermined level, and a signal of a predetermined broadcast channel are selectively selected from the branch output of the signal branching unit. A channel selection / demodulation means for demodulating predetermined data from the signal of the broadcast channel, and a predetermined broadcast channel from the branch output of the signal branching means. A channel selection / demodulation unit that selectively demodulates a channel signal and demodulates predetermined data from the broadcast channel signal, and calculates a bit error rate from the predetermined data demodulated by the channel selection / demodulation unit In addition, the bit error rate obtained from the calculation result and a predetermined reference value of the bit error rate provided in advance are compared and determined, and based on the determination result, the output amplified by the signal amplifying means is set to a predetermined level. As described above, the signal attenuating means includes a monitoring / control means for performing processing for controlling the amount of attenuation.

According to a second aspect of the present invention, in the digital broadcast retransmitting apparatus according to the first aspect, the signal processing unit passes at least a reception signal received by the reception antenna and branches a part of the reception signal. A signal branching means, a first frequency converting means for converting the frequency from the output of the signal branching means to an intermediate frequency band lower than the received signal, and a desired signal to be retransmitted from the output of the first frequency converting means Intermediate frequency processing means including a band-pass filter for passing the signal, second frequency conversion means for converting the output of the intermediate frequency signal processing means into the frequency band of the received digital broadcast, and the second frequency conversion means Signal attenuating means for attenuating the output of the signal attenuator by a predetermined level, signal amplifying means for amplifying the output of the signal attenuator to a predetermined level, the first frequency converting means and the second The local oscillation signal generating means for generating a local oscillation signal for frequency conversion of the frequency converting means, and a.

According to a third aspect of the present invention, in the digital broadcast retransmitting apparatus according to the first aspect, the signal processing unit is a first frequency converting means for frequency converting at least the received signal into an intermediate frequency band lower than the received signal. And an intermediate frequency processing means including a band pass filter for passing a desired signal to be retransmitted from the output of the first frequency conversion means, and a part of the received signal passing through the output of the intermediate frequency processing means Branching means, second frequency converting means for frequency converting the output of the signal branching means to the frequency band of the received digital broadcast, and attenuating the output of the second frequency converting means by a predetermined level Signal attenuating means, signal amplifying means for amplifying the output of the signal attenuator to a predetermined level, and a station for frequency conversion of the first frequency converting means and the second frequency converting means The local oscillation signal generating means for generating an oscillating signal, and a.

According to a fourth aspect of the present invention, in the digital broadcast retransmitting device according to any one of the first to third aspects, the monitoring / control means includes the bit error rate and a predetermined reference value obtained by calculation. If the bit error rate is determined to be greater than a predetermined reference value based on the comparison / determination result, a state display signal indicating the state is generated and output.

According to a fifth aspect of the present invention, in the digital broadcast retransmitting apparatus according to any one of the first to fourth aspects, at least the processing by the monitoring / control means is a guard interval added to the digital broadcast signal. Configured to take place within a period of time.

According to a sixth aspect of the present invention, in the digital broadcast retransmission apparatus according to any one of the first to fifth aspects, a signal received by the receiving antenna is set to a predetermined number on the input side of the signal processing unit. Distributing means for distributing is provided, and on the output side of the signal processing section, combining means for combining the output signals of the plurality of signal processing sections is provided.

According to a seventh aspect of the present invention, in the digital broadcast retransmission apparatus according to any one of the first to sixth aspects, the reception antenna is configured using an antenna having a sharper directivity characteristic than the transmission antenna.

According to the first aspect of the present invention, a digital broadcast configured to receive a digital broadcast wave by a receiving antenna and retransmit the signal from the receiving antenna as a digital broadcast wave from the transmitting antenna by performing predetermined signal processing. In the retransmission apparatus, at least a signal branching unit that passes a signal received by the receiving antenna and branches a part of the signal, a signal attenuating unit that attenuates an output of the signal branching unit by a predetermined level, and a signal attenuation A signal amplifying means for amplifying the output of the means to a predetermined level, and selectively selecting a signal of a predetermined broadcast channel from the branch output of the signal branching means, and the signal of the broadcast channel The channel selection / demodulation means for demodulating the predetermined data from the signal and the branch output of the signal branching means selectively the signal of the predetermined broadcast channel A channel selection / demodulation means for demodulating predetermined data from the signal of the broadcast channel, a bit error rate from the predetermined data demodulated by the channel selection / demodulation means, and the calculation result The bit error rate obtained from the above and a predetermined reference value of the bit error rate provided in advance are compared and determined, and based on the determination result, the signal amplified so that the output after amplification by the signal amplification means becomes a predetermined level. Since it consists of monitoring and control means that performs processing to control the attenuation amount of the attenuation means,
Even if a signal sneaks from the transmitting antenna to the receiving antenna due to changes in the surrounding environment after installation, changes in the installation status, changes over time in electrical characteristics, etc., a "bit error rate error" By constantly monitoring the signal degradation due to "abnormal bit error rate", the signal attenuation means is controlled by a predetermined amount, the output level radiated from the transmitting antenna is lowered by a predetermined amount, and the wraparound of the radio wave is avoided. With this simple and inexpensive method, it is possible to prevent signal degradation due to sneaking in and, in the worst case, the retransmission apparatus oscillating and destroying the apparatus.
Also, considering the case where “abnormal bit error rate” occurs in the system between the master station and the receiving antenna, the output level is not suddenly stopped, but the output level is lowered step by step by a predetermined amount. By controlling the radio wave radiated from the transmitting antenna to be gradually weakened, it is possible to avoid “abnormal bit error rate” while maintaining retransmission.
In addition, since the wraparound phenomenon is avoided while gradually reducing the output level in this way, in the state where the wraparound is avoided by lowering the output level, the service area when the retransmitter is at full power and In comparison, although the target service area covers a slightly narrow area, it is possible to maintain retransmission with a signal that does not wrap around, and all households in the service area subject to retransmission are subject to signal degradation due to the sneak phenomenon. Therefore, it is possible to prevent a reception failure from occurring.

According to a second aspect of the present invention, in the digital broadcast retransmitting apparatus according to the first aspect, the signal processing unit passes at least a received signal received by the receiving antenna and transmits a part of the received signal. The signal branching means to be branched, the first frequency converting means for converting the frequency from the output of the signal branching means to an intermediate frequency band lower than the received signal, and the output of the first frequency converting means should be retransmitted. Intermediate frequency processing means including a band-pass filter for passing a desired signal, second frequency conversion means for converting the output of the intermediate frequency signal processing means into the frequency band of the received digital broadcast, and the second frequency Signal attenuating means for attenuating the output of the converting means by a predetermined level, signal amplifying means for amplifying the output of the signal attenuator to a predetermined level, the first frequency converting means, The local oscillation signal generating means for generating a local oscillation signal for frequency conversion of the second frequency converting means, since it is configured from,
The first frequency converter converts the received signal into an intermediate frequency band that has a lower frequency band and is easy to handle, and is represented by, for example, filter means for removing signals other than signals desired to be retransmitted. The signal processing means can be easily designed.

According to a third aspect of the present invention, in the digital broadcast retransmitting device according to the first aspect, the signal processing unit at least converts the received signal to a first intermediate frequency band lower than the received signal. An intermediate frequency processing means including a conversion means, a band-pass filter for passing a desired signal to be retransmitted from the output of the first frequency conversion means, and an output of the intermediate frequency processing means, Signal branching means for branching a part, second frequency converting means for converting the output of the signal branching means into the frequency band of the received digital broadcast, and the output of the second frequency converting means for a predetermined level A signal attenuating means for attenuating, a signal amplifying means for amplifying the output of the signal attenuator to a predetermined level, and frequency conversion of the first frequency converting means and the second frequency converting means. The local oscillation signal generating means for generating a local oscillation signal, since it is configured from,
The first frequency converter converts the received signal into an intermediate frequency band that has a lower frequency band and is easy to handle, and is represented by, for example, filter means for removing signals other than signals desired to be retransmitted. In addition to simplifying the design of the signal processing means, the channel selection / demodulation means connected to the branch output of the signal branching means should be compatible with the intermediate frequency band that is easy to handle, and have a predetermined bandwidth. By providing the filter means, the channel selection section need not be provided, the configuration of the channel selection / demodulation means is simplified, and an inexpensive retransmission apparatus can be provided.

According to a fourth aspect of the present invention, in the digital broadcast retransmitting apparatus according to any one of the first to third aspects, the monitoring / control means is configured to calculate the bit error rate obtained by calculation and a predetermined reference. Based on the comparison / determination result with the value, if it is determined that the bit error rate is greater than the predetermined reference value, a state display signal indicating the state is generated and output.
The detection of “abnormal bit error rate” is displayed on the display means of the retransmitter using the warning signal of “abnormal bit error rate”, or it is carried to the facility manager via the public telephone network. You can use a telephone to warn you, and you can quickly respond to “abnormal bit error rates”.
In addition, when “abnormal bit error rate” cannot be avoided, that is, when it cannot be avoided by output level control, or “abnormal bit error rate” occurs in the system between the master station and the receiving antenna. In some cases, after a predetermined time, the signal attenuating means functions as a squelch circuit, and the attenuation amount is maximized, and an “output stop” warning signal is displayed on the display means provided in the retransmission apparatus, It is possible to notify the facility manager by means of, etc., and it is possible to quickly respond to the output stop.

According to a fifth aspect of the present invention, in the digital broadcast retransmission apparatus according to any one of the first to fourth aspects, at least the processing by the monitoring / controlling means is a guard added to the digital broadcast signal. Since it was configured to be performed within the interval,
TV images can be processed without block noise or blackouts.

According to a sixth aspect of the present invention, in the digital broadcast retransmission apparatus according to any one of the first to fifth aspects, a signal received by the receiving antenna is predetermined on the input side of the signal processing unit. Since the distribution means for distributing the number is provided, and the output side of the signal processing unit is configured to include a synthesis unit for combining the output signals of the plurality of signal processing units,
Supports multiple channel retransmission.

According to a seventh aspect of the present invention, in the digital broadcast retransmission apparatus according to any one of the first to sixth aspects, the reception antenna is configured using an antenna having a sharper directivity characteristic than the transmission antenna. So
For example, by using a parabolic antenna as the receiving antenna, the amount of sneak from the transmitting antenna can be greatly reduced.

Hereinafter, an example of an embodiment embodying the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic block diagram of a digital broadcast retransmission apparatus according to the first embodiment of the present invention, and FIG. 2 is a schematic block diagram provided with a plurality of digital broadcast retransmission apparatuses according to the first embodiment of the present invention. . FIG. 3 shows an example of a flowchart showing signal processing in the monitoring / control means provided in the first embodiment of the present invention. FIG. 4 is a schematic block diagram of a digital broadcast retransmission apparatus according to the third embodiment of the present invention. FIG. 5 is a schematic block diagram of a digital broadcast retransmission apparatus according to the third embodiment of the present invention.
In the following embodiments, those having the same functions are given the same reference numerals unless otherwise specified, and detailed description thereof is omitted.

FIG. 1 is a schematic block diagram showing the configuration of a digital broadcast retransmission apparatus according to the first embodiment of the present invention. In FIG. 1, 1 is a digital broadcast retransmitting device, 2 is a receiving antenna, and 3 is a transmitting antenna. The high-frequency signal path includes at least a signal branching unit 11, a signal attenuating unit 15, and a signal amplifying unit 18, and a data signal path includes a channel selection / demodulation unit 12 and a monitoring / control unit 13. Yes. Reference numeral 28 denotes signal processing means. In the embodiment of the present invention, this signal processing means is a filter means.

Next, details of the digital broadcast retransmission apparatus 1 will be described. The receiving antenna 2 is an antenna for receiving terrestrial digital broadcast waves, so-called UHF band radio waves. In the embodiment of the present invention, for example, by using a parabolic antenna having excellent directivity characteristics, Can be cut off. The signal of the terrestrial digital broadcast wave received by the receiving antenna 2 passes through this signal and is output, and is input to the signal branching means 11 for branching a part of the signal. The signal branching means 11 is composed of a branch circuit provided with a branch transformer formed by winding a polyurethane wire around a ferrite core, for example.
The output from the signal branching means 11 is input to the signal processing means 28. This signal processing means 28 is for restricting the passage of a signal, performing signal compensation or signal amplification, and in the embodiment of the present invention, for example, a signal in a predetermined band is selectively passed, and the signal is out of the predetermined band. Consists of filter means for blocking. The signal that has passed through the filter means 28 is input to a signal attenuating means 15 that attenuates the output by a predetermined level. In the embodiment of the present invention, the signal attenuating means 15 is composed of, for example, a PIN diode as a high-frequency element, and is configured so that the amount of attenuation can be appropriately varied by controlling the voltage.
The output from the signal attenuating means 15 is appropriately amplified by a signal amplifying means 18 for amplifying a high frequency signal composed of, for example, a diode or an IC as a high frequency element, supplied to the transmission antenna 3, and digital broadcasting from the transmission antenna 3. It is emitted as a wave.
In the first embodiment of the present invention, at least the signal branching unit 11, the signal attenuator 15, and the signal amplifying unit 18 constitute the signal processing unit 10 described in the claims.

Next, the channel selection / demodulation means 12 accepts a terrestrial digital broadcast wave from the branch output of the signal branching means 11, selectively selects a signal of a predetermined broadcast channel from the broadcast wave, This is a so-called tuner that demodulates predetermined data from a signal included in a channel.
In the embodiment of the present invention, the basis for obtaining the BER (Bit Error Rate: hereinafter referred to as BER) of the signal received by the receiving antenna 2 from the channel selection / demodulation means 12. Get the data.

The monitoring / control unit 13 acquires predetermined data demodulated by the channel selection / demodulation unit 12 (basic data on which BER is based in the embodiment of the present invention), calculates the BER from the data, Control for comparing / determining the BER obtained from the result and a predetermined reference value of BER provided in advance in the monitoring / control unit 13 and controlling the attenuation amount of the signal attenuation unit 15 based on the result For example, a CPU (Central Processing Unit) is configured to generate a voltage.
That is, when the monitoring / control unit 13 according to the first embodiment of the present invention determines that the acquired BER is the same as the predetermined reference value (no change) or small (good), the signal amplification unit 18 performs the amplification. The amount of attenuation of the signal attenuating means 15 is controlled so that the output becomes a predetermined level, and when the BER is determined to be larger (bad) than the predetermined reference value, the output after amplification by the signal amplifying means 18 is predetermined. The attenuation amount of the signal attenuation means 15 is controlled so as to be lower than the level by a predetermined amount.
In the embodiment of the present invention, an example of a single retransmission apparatus is shown. However, as shown in FIG. 2, a signal processor 10 has a distributor on the input side and a mixer on the output side. You may comprise so that it may become a series.

Here, an example of the operation of the monitoring / control unit 13 will be described with reference to the flowchart shown in FIG.
S10 shows the initial state of the digital broadcast retransmitting apparatus, and the attenuation amount of the signal attenuation means 15 is set to be the minimum value. Next, in S12, the BER is calculated using the data acquired by the channel selection / demodulation means 12 from the signal received by the receiving antenna. In S14, it is determined whether the calculated BER value is larger than a predetermined reference value provided in the monitoring / control means 13 in advance (BER is bad) or smaller (BER is good). At this time, if it is determined that the BER of the received signal is equal to or smaller than the predetermined reference value, the process returns to S10 and the BER is continuously monitored. This monitoring is configured such that the timing for measuring the BER can be arbitrarily set in advance, and can be continuously monitored every predetermined time.

Next, if it is determined in S14 that the BER of the received signal is larger than the predetermined reference value, the process proceeds to S16, and a warning signal for notifying the occurrence of “BER abnormality” is generated. This “BER abnormality” warning signal is used to display “BER abnormality” on the retransmission apparatus by turning on a display means such as an LED which is not shown in the figure provided in the retransmission apparatus. Or, based on the warning signal of “BER abnormality”, the terminal device provided in the re-transmission device is used to notify the facility manager through the public telephone network. Is for. The “BER abnormality” warning signal may be continuously output once the “BER abnormality” is detected, or may be continuously output until a predetermined time elapses.

Next, in S18, the number of times that “BER abnormality” is detected in the BER measurement is counted. Further, in S20, an arbitrary first reference number n (times) is set in advance as a pass / fail judgment criterion for the number of measurements for which “BER abnormality” is measured, and the number of measurements for which “BER abnormality” is detected is set. If the predetermined first reference number n (times) is not exceeded, the process proceeds to S202, and the signal attenuating means 15 is controlled and amplified to determine whether the "BER abnormality" is continuous or temporary. The BER is monitored again by changing the output level later. That is, in the embodiment of the present invention, if the “BER abnormality” is first confirmed (first measurement), the attenuation amount of the signal attenuation means 15 is increased from the monitoring / control means 13 by a predetermined amount α (dB). A control signal is generated and output so as to be performed (lower the output level). Next, when the output level is lowered by a predetermined amount in this way, the process returns to S12, and data is again obtained from the channel selection / demodulation means 12, and the BER is calculated.

Next, if the BER newly acquired in S14 is within the normal value, the process returns to S10 and monitoring is continued. If the BER newly acquired in S14 again shows an abnormal value, the warning signal “BER abnormal” is continuously generated in S16, and the “BER abnormal” is counted for the second time in S18, and in S202. The attenuation amount of the signal attenuation means 15 is increased by 2α (dB), and the process returns to S12. Then, in S20, this operation is repeated until the number of measurement of “BER abnormality” reaches the first reference number n (times). Therefore, if the number of times of measurement of “BER abnormality” is recognized n times, the attenuation amount of the signal attenuation means 15 is α × n (dB), and the output level is lowered by that amount and radiated.

Next, if it is determined in S20 that the number of times of measurement of “BER abnormality” exceeds the first reference number n (times) and becomes n + 1 (times), the attenuation amount of the signal attenuation means 15 is set to the maximum value in S22. The signal attenuating means 15 operates as a squelch circuit. Further, in S24, the BER acquired when the number of times of measurement of “BER abnormality” is n + 1 (times) is stored as a first reference value. Then, in S26, an “output stop” warning signal for notifying that the retransmission apparatus is in the output stop state is generated. This “output stop” warning signal may also be used to display the display means provided in the re-transmission device in the same manner as the above-mentioned “BER abnormality” warning signal. May be used to notify the administrator.

In the above embodiment, the output level is sequentially lowered to change the amount of wraparound, and the output level is set to the point where the BER is improved. However, the present invention is not particularly limited to this example. , If it is determined that the BER is larger than the predetermined reference value, the output level may be decreased by a predetermined amount (for example, an amount corresponding to the above-described attenuation amount α × n (dB)) at a time. In addition, the BER measurement result may be set such that the BER can be maintained within a predetermined reference value while gradually increasing the output level while monitoring the BER from a state where the output level has decreased by a predetermined amount. If the output level is changed by a predetermined amount based on this, the present invention is not particularly limited to the embodiment.
Further, a series of processing time until the output level by the monitoring / control means 13 is set to a predetermined level is a guard added to the digital broadcast signal by using, for example, a CPU having a high operating frequency and a high processing capability. If it is performed within the interval period (126 μs), it is possible to process without causing block noise or blackout (video loss) in the television image. In addition, the number of times of processing can be increased by using a high processing capability.

Next, the operation state after the output stop state is shown. In the embodiment of the present invention, monitoring of BER at the input is continued even when the output is stopped.
In the timer circuit of S30, if a predetermined time has elapsed after the squelch circuit is operated, the BER is recalculated in S32 using the latest data obtained from the channel selection / demodulation means 12. Further, in S34, the BER remeasured in S32 is compared with the BER as the first reference value stored in S24, and the BER remeasured in S32 is stored in the first memory stored in S24. If it is determined that it is equal to or larger than the reference value (no improvement is seen in the BER), the process proceeds to S306.
In S306, if it is determined that the BER remeasured in S32 is larger than the predetermined reference value, the process returns to S22 and the monitoring of the BER is continued in the squelch operation state in which the attenuation amount of the signal attenuation means is the maximum value. In S306, if it is determined that the BER remeasured in S32 is smaller than the predetermined reference value, the process returns to S30 to continue monitoring the BER.

Next, in S34, if it is determined that the BER reacquired in S32 is smaller than the BER as the first reference stored in S24 (BER has been improved), the process proceeds to S36. In S36, the BER as the first reference value stored in S24 is reset, and the BER recalculated in S32 is newly stored as the second reference value. Further, in S38, the number of times when it is confirmed that the newly acquired BER is improved by comparing the recalculated BER with the stored BER is counted.
Furthermore, in S40, an arbitrary second reference number n (times) is set in advance as a determination criterion for this count. The second reference number is set to be the same as the first reference number determined in S20, and the BER improvement confirmation does not exceed the predetermined second reference number n (times) in S402. The attenuation amount of the signal attenuating means 15 is controlled, and a series of operations such as re-measurement of the BER is repeated in S32, and it is determined whether or not the BER is in a recovery tendency.

That is, in S402, when it is confirmed (first time) that the BER is in a recovery tendency at the time of re-measurement after a predetermined time has passed after entering the squelch operation state, the attenuation amount of the signal attenuation means 15 is set in S22. The maximum value (squelch operation state) is controlled to be α × n (dB) so that the radio wave is retransmitted from the transmission antenna. Along with this, the generation of the “output stop” warning signal is canceled in S404, and the fact that the retransmission has been resumed is displayed on the display means or the administrator is notified. Next, when the output level is increased in this way, the process returns to S32, and the BER of the input signal is calculated in the state where the data is acquired again from the channel selection / demodulation means 12 and the output level is increased. Next, if the BER newly acquired with the output level raised in S34 is larger than the BER as the second reference value stored in the memory, the process proceeds to S306. In S306, the BER newly acquired with the output increased is compared with the predetermined reference value. If it is determined that the BER newly acquired with the output increased is larger than the predetermined reference value, the process proceeds to S22. Monitoring of the BER is continued in a squelch operation state in which the return signal attenuation means has the maximum attenuation. Further, if it is determined that the newly acquired BER with the output increased in S32 is smaller than the predetermined reference value, the attenuation amount of the signal attenuation means 15 is maintained at α × n (dB) set in S402. Returning to S30, monitoring of BER is continued.

If the newly acquired BER in the state where the output level is increased in S34 shows a value smaller than the stored BER, and "BER improvement" is confirmed (second time), the second stored in S36 is stored. BER as a reference value of the BER is reset, and a newly acquired BER value is newly stored in a state where the output level is raised. Further, in S38, the number of “BER improvement” confirmations is counted. In this example, after the squelch circuit is activated, the first BER improvement is confirmed for the first time, and the first BER improvement is confirmed. When the output level is first raised, the BER improvement is confirmed. Then it will be the second “BER improvement” confirmation. This operation is repeated until the “BER improvement” confirmation count reaches the second reference count n (times). That is, in S402, based on the “BER improvement” confirmation count in S38, if the count is 1, the attenuation of the signal attenuation means 15 is α × n (dB), and if the count is 2, α × n−α ( dB), if the count is 3, α × n−2α (dB)..., when the count reaches the second reference number n (times), α × n−α × (n−1) (dB ), The output level is gradually increased, the BER value is confirmed in S32, and the emission of the retransmitted radio wave is resumed.

If “BER improvement” is confirmed to be n + 1 in S40, the attenuation amount of the signal attenuating means is controlled to the minimum value in S42, and a cancellation signal for the “BER abnormal” warning signal is generated in S44, indicating that the BER is normal. Is displayed on the display means or notified to the administrator. When the “BER abnormality” is not detected in this way, the process returns to S10 and continues to monitor BER.

The output level control in this squelch state has shown an example in which the output level is sequentially raised to change the amount of wraparound and the output level is set at a point where the BER is improved. However, the output level control is not particularly limited to this embodiment. Alternatively, if it is determined that the BER is smaller than the predetermined reference value, the output level may be increased by a predetermined amount at a time.
In addition, a series of processing time until the output level by the monitoring / control means 13 described above is set to a predetermined level is added to the digital broadcast signal by using, for example, a CPU whose operating frequency is high and processing capability is high. If the processing is performed within the guard interval period (126 μs), processing can be performed without causing block noise or blackout in the television image. In addition, the number of times of processing can be increased by using a high processing capability.

Here, the operation and effect of the digital broadcast retransmitting apparatus 1 configured as described above will be described. The digital broadcast retransmitting apparatus 1 of the present invention is suitable as a retransmitting apparatus for a radio wave disturbance area in terrestrial digital broadcasting, and it is considered to retransmit by SFN. In this case, if the radio wave radiated from the transmission antenna 3 provided in the retransmitting device 1 wraps around the receiving antenna 2 provided in the retransmitting device 1 and receiving the radio wave from the master station, the signal deterioration or worst case may occur. In this case, the retransmission apparatus may oscillate. To cope with this, it is possible to maintain the physical distance between the receiving antenna and the transmitting antenna. However, if it is too far away, it will be disadvantageous in terms of cost because it is necessary to secure the installation location and to consider the support brackets. become. Furthermore, when the digital broadcast retransmitting apparatus 1 is installed, a wraparound phenomenon may occur due to a change in characteristics or an environmental change due to buildings or trees in the surrounding area. A reception failure occurs in the entire radio interference area to be retransmitted.

Therefore, in the present invention, in the state when the wraparound phenomenon occurs, attention is paid to the change in BER that greatly affects the received image in the data obtained from the received signal of the terrestrial digital broadcast, and the deterioration of the BER. A limit value that affects the image is set in the monitoring / control unit 13 in advance as a predetermined reference value, and the BER at the input is always monitored by the channel selection / demodulation unit 12 and the monitoring / control unit 13. , Compare and determine the data obtained from the monitoring and a predetermined reference value, and if it is determined that a “BER abnormality” has occurred, the output level is lowered by a predetermined amount to avoid signal deterioration due to wraparound It is configured to do.

Furthermore, if the “BER abnormality” is not improved even if the output level is lowered by a predetermined amount, a “BER abnormality” in the system between the master station and the receiving antenna or a failure of the retransmission apparatus itself can be considered. After lapse of time, the squelch circuit can be operated to prevent unnecessary radio waves from being radiated from the output.

Furthermore, even when the squelch circuit is in operation, the BER at the input is continuously monitored. If “BER abnormality” is not recognized, the output level is set to a predetermined amount while confirming whether or not BER abnormality occurs again. It is configured so that retransmission can be automatically restored by raising it little by little.

In other words, according to the digital broadcast retransmitting apparatus 1 of the present invention, a signal wraps around from the transmitting antenna 3 to the receiving antenna 2 due to changes in the surrounding environment after installation, changes in the installation state, secular changes in electrical characteristics, and the like. Even if signal degradation occurs due to this, by constantly monitoring the “BER abnormality” of the input signal that accompanies this, if the “BER abnormality” is confirmed, the output level is lowered by a predetermined amount. Since the radio wave radiated from the transmitting antenna 3 is weakened so that the sneak phenomenon can be avoided, the signal degradation due to sneaking or the retransmission device oscillates and destroys the device by a simple and inexpensive method. Can be prevented.

Also, is it possible to avoid the wraparound phenomenon by controlling the electric wave radiated from the transmitting antenna 3 to be gradually weakened while decreasing the output level step by step by a predetermined amount instead of suddenly stopping the output level? Since it is configured to check whether or not, it is easy to know whether the cause of the “BER abnormality” is caused by wraparound or in the system between the master station and the receiving antenna 2. In addition, if a “BER error” occurs in the system between the master station and the receiving antenna 2 or if it is determined that it cannot be avoided due to malfunction of the device itself, a squelch circuit will operate, causing unnecessary radio waves to be interrupted. Is not given.

In addition, since the wraparound phenomenon is avoided while gradually reducing the output level in this way, in the state where the wraparound is avoided by lowering the output level, the service area when the retransmitter is at full power and In comparison, although the target service area covers a slightly narrow area, it is possible to maintain retransmission with a signal that does not wrap around, and all households in the service area subject to retransmission are subject to signal degradation due to the sneak phenomenon. Therefore, it is possible to prevent a reception failure from occurring.

Furthermore, when “BER abnormality” is detected, the “BER abnormality” is displayed on the display means provided in the re-transmission device, or the mobile phone held by the facility manager is warned via the public telephone network. By generating a warning signal of “BER abnormality”, it is possible to quickly cope with “BER abnormality”.
In addition, when a state where “BER abnormality” cannot be avoided continues, that is, when it cannot be avoided only by controlling the output level, or when “BER abnormality” occurs in the system between the master station and the receiving antenna, After a predetermined time, the signal attenuating means 15 is configured as a squelch circuit so that the amount of attenuation is maximized, and a warning signal of “output stop” is displayed using the display means provided in the retransmitting apparatus 1 or a public telephone network. It is possible to report to the facility manager's mobile phone, etc., and to quickly deal with the “output stop”.

Furthermore, even when the squelch circuit is in operation, the BER at the input is continuously monitored. If the “BER abnormality” is no longer recognized, the squelch circuit is released and the output level is gradually increased by a predetermined amount. However, the transmission is automatically restored while confirming whether or not a BER abnormality due to wraparound has occurred, and output stop cancellation notification and BER normality notification are displayed on the display means according to the recovery status. , You can contact the facility manager, and you can save the labor for maintenance of the facility management.
Note that one or both of the “BER abnormality” warning signal and the “output stop” warning signal are the state display signals described in the claim holes.

Next, a second embodiment of the present invention will be described with reference to FIG. In the following description, the same components as those in the digital broadcast retransmission apparatus of the first embodiment are given the same reference numerals, and detailed description thereof is omitted.

The signal processing unit 10 according to the second embodiment passes the received signal received by the receiving antenna 2 and between the signal branching means 11 and the signal attenuating means 15 for branching a part of the received signal. A first frequency converting means 21 that converts the frequency from the output of the branching means 11 to an intermediate frequency band lower than the received signal, and a band that passes the desired signal to be retransmitted from the output of the first frequency converting means 21 Digital broadcast retransmission apparatus comprising: intermediate frequency processing means 28 including a pass filter; and second frequency conversion means 25 for converting the output of the intermediate frequency signal processing means 28 into the frequency band of the received digital broadcast. 1. Reference numeral 22 denotes a local oscillator.
According to the second embodiment of the present invention, since the received signal is converted into an intermediate frequency band that is lower in frequency band and easy to handle by the first frequency converter, for example, signals other than the signal that is desired to be retransmitted are removed. Therefore, it is possible to easily design signal processing means represented by the filter means 18 and the like.

Next, a third embodiment of the present invention will be described with reference to FIG. In the following description, the same components as those in the digital broadcast retransmission apparatus of the first embodiment are given the same reference numerals, and detailed description thereof is omitted.

The signal processing unit 10 according to the third embodiment retransmits the received signal from the first frequency converting unit 21 that converts the frequency of the received signal to an intermediate frequency band lower than the received signal, and the output of the first frequency converting unit 21. An intermediate frequency processing means 28 including a band-pass filter that passes a desired signal to be transmitted; a signal branching means 11 that passes the output of the intermediate frequency processing means 28 and branches a part of the received signal; and the signal branching A second frequency converting means 21 for converting the output of the means 11 into the frequency band of the received digital broadcast; a signal attenuating means 15 for attenuating the output of the second frequency converting means 21 by a predetermined level; This is a digital broadcast retransmitting apparatus 1 having signal amplifying means 18 for amplifying the output of the attenuator 15 to a predetermined level. Reference numeral 22 denotes a local oscillator.
According to the third embodiment of the present invention, the received signal is converted into an intermediate frequency band that is lower in frequency band and easy to handle by the first frequency converter, and therefore, for example, signals other than the signal that is desired to be retransmitted are removed. Therefore, it is possible to easily design signal processing means represented by the filter means 18 and the like. Furthermore, the channel selection / demodulation unit 12 connected to the branch output of the signal branching unit may correspond to an easily handled intermediate frequency band, and the filter unit 28 is provided so that the channel selection unit is not provided. Well, the configuration of the channel selection / demodulation means 12 can be simplified and inexpensively configured.

In addition, this invention is not limited to the said embodiment, It is also possible to change suitably the structure of each part in the range which does not deviate from the meaning of this invention.

1 shows a schematic block diagram of a first embodiment according to the present invention. An example in which a plurality of retransmission apparatuses according to the first embodiment of the present invention are provided is shown. It is an example of the flowchart which shows operation | movement of the monitoring and control means with which 1st Embodiment concerning this invention was equipped. The schematic block diagram of 2nd Embodiment which concerns on this invention is shown. The schematic block diagram of 3rd Embodiment which concerns on this invention is shown.

DESCRIPTION OF SYMBOLS 1 ... Digital broadcast re-transmission apparatus, 2 ... Reception antenna, 3 ... Transmission antenna, 5 ... Distribution means, 6 ... Mixing means, 10 ... Signal processing apparatus, 11 ... Signal branching means, 12 ... Channel selection / demodulation means, 13 ... Monitoring / controlling means, 15 ... signal attenuating means, 18 ... signal amplifying means, 21 ... first frequency converting means, 22 ... local oscillator, 25 ... second frequency converting means, 28 ... signal processing means (filter means).

Claims (7)

In a digital broadcast retransmission apparatus configured to receive a digital broadcast wave at a reception antenna and retransmit the signal from the reception antenna as a digital broadcast wave from a transmission antenna by performing predetermined signal processing,
At least a signal branching means for passing a signal received by the receiving antenna and branching a part of the signal, a signal attenuating means for attenuating the output of the signal branching means by a predetermined level, and an output of the signal attenuating means A signal amplifying means for amplifying to a level, a signal processing unit comprising:
A channel selection / demodulation means for selectively selecting a signal of a predetermined broadcast channel from a branch output of the signal branching means, and demodulating predetermined data from the signal of the broadcast channel;
The bit error rate is calculated from the predetermined data demodulated by the channel selection / demodulation means, and the bit error rate obtained from the calculation result is compared with a predetermined reference value of the bit error rate provided in advance. Monitoring and control means for performing processing for controlling the attenuation amount of the signal attenuating means so that the output after amplification by the signal amplifying means becomes a predetermined level based on the determination result;
A digital broadcast re-transmission device comprising:
The signal processing unit is at least
A signal branching means for passing a received signal received by the receiving antenna and branching a part of the received signal;
First frequency conversion means for converting the frequency from the output of the signal branching means to an intermediate frequency band lower than the received signal;
Intermediate frequency processing means including a band-pass filter for passing a desired signal to be retransmitted from the output of the first frequency conversion means;
Second frequency converting means for frequency converting the output of the intermediate frequency signal processing means to the frequency band of the received digital broadcast;
Signal attenuating means for attenuating the output of the second frequency converting means by a predetermined level;
Signal amplifying means for amplifying the output of the signal attenuator to a predetermined level;
Local oscillation signal generating means for generating a local oscillation signal for frequency conversion of the first frequency converting means and the second frequency converting means;
The digital broadcast retransmitting apparatus according to claim 1, comprising:
The signal processing unit is at least
First frequency converting means for converting a received signal to an intermediate frequency band lower than the received signal;
Intermediate frequency processing means including a band pass filter for passing a desired signal to be retransmitted from the output of the first frequency conversion means;
A signal branching means for passing the output of the intermediate frequency processing means and branching a part of the received signal;
Second frequency converting means for frequency converting the output of the signal branching means to the frequency band of the received digital broadcast;
Signal attenuating means for attenuating the output of the second frequency converting means by a predetermined level;
Signal amplifying means for amplifying the output of the signal attenuator to a predetermined level;
Local oscillation signal generating means for generating a local oscillation signal for frequency conversion of the first frequency converting means and the second frequency converting means;
The digital broadcast retransmitting apparatus according to claim 1, comprising:
The monitoring / control means indicates the state when the bit error rate is determined to be larger than the predetermined reference value based on the comparison / determination result between the bit error rate and the predetermined reference value obtained by calculation. Generate and output a status display signal,
The digital broadcast retransmitting apparatus according to any one of claims 1 to 3, wherein
5. The digital broadcast retransmission apparatus according to claim 1, wherein at least the processing by the monitoring / control unit is performed within a guard interval added to the digital broadcast signal. .
Distributing means for distributing a predetermined number of signals received by the receiving antenna is provided on the input side of the signal processing unit, and the output signals of the plurality of signal processing units are combined on the output side of the signal processing unit With synthesis means,
The digital broadcast retransmitting apparatus according to any one of claims 1 to 5, wherein the digital broadcast retransmitting apparatus.
The digital broadcast retransmission apparatus according to any one of claims 1 to 6, wherein an antenna having a directivity characteristic sharper than that of the transmission antenna is used as the reception antenna.

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