JP5090886B2 - Receiver circuit and radio - Google Patents

Description

  The present invention relates to a wireless device used in a bidirectional wireless system, and more particularly to a receiving circuit and a wireless device that can normally receive CW (Cyclic Wave) noise from other devices.

[Two-way radio system]
A wireless device used in a conventional bidirectional wireless system is a wireless device that operates on a weak radio wave that employs a spread spectrum (SS) system.
2. Description of the Related Art A conventional two-way radio system includes a master radio having a transmitter and a receiver, and a slave radio having a transmitter and a receiver. An operation command is transmitted from the device to the parent device, and the parent device operates according to the command.

Further, the master unit transmits a command transmission status response and master unit status information to the slave unit.
In other words, the conventional bidirectional wireless system is a weak wireless system capable of bidirectional communication (half duplex) employing SS.

  The above two-way wireless system is operated by the slave unit. The master unit receives commands from the slave unit by intermittently receiving the slave unit's transmission, and the slave unit only operates when it wants to operate. Because of the operation state, power consumption can be greatly reduced.

[Receiving circuit of conventional master unit: FIG. 5]
Next, the configuration of the receiving circuit of the conventional base unit will be described with reference to FIG. FIG. 5 is a block diagram showing a configuration of a receiving circuit in a conventional base unit.
As shown in FIG. 5, the receiving circuit in the conventional master unit includes a carrier demodulating unit 11, an IF (Intermediate Frequency) frequency detecting unit 12, a carrier data generating unit 13, a correlation peak detecting unit 14, and a received data decoding unit. Part 15.

  The carrier demodulator 11 removes the IF carrier component from the input received IF signal, further performs down-sampling processing, and sends the IF frequency detector 12, the correlation peak detector 14, and the received data decoder 15. Output.

The IF frequency detection unit 12 performs FFT (Fast Fourier Transform) processing on the signal input from the carrier demodulation unit 11 to detect an IF frequency and outputs the IF frequency to the carrier data generation unit 13.
The carrier data generation unit 13 performs frequency correction processing according to the frequency detection result from the IF frequency detection unit 12 and generates IF carrier data to be supplied to the carrier demodulation unit 11.

The correlation peak detection unit 14 performs correlation detection processing on the carrier demodulated data output from the carrier demodulation unit 11 and performs correlation peak detection.
The reception data decoding unit 15 performs despreading processing and BPSK (Bi-Phase Shift Keying) demodulation processing after synchronization is established, detects a synchronization word, and performs user data decoding processing (data reception processing).

[Conventional master unit intermittent reception processing flow: FIG. 6]
Next, discontinuous reception processing in the conventional master unit will be described with reference to FIG. FIG. 6 is a flowchart of the intermittent reception process in the conventional base unit.
As shown in FIG. 6, when reception processing is started in the parent device, the reception circuit of the parent device starts an intermittent reception operation (S41), and the carrier demodulator 11 removes the IF carrier component, and the IF frequency The detection unit 12 performs FFT processing and investigates the peak carrier frequency component (S42).

  Next, the correlation peak detection unit 14 performs a process of detecting a correlation peak of the spread spectrum (SS) method (S44), and determines whether or not there is a correlation peak (S45). If there is no correlation peak (in the case of No), intermittent reception is terminated (S50), and the process returns to step S41.

  When there is a correlation peak (in the case of Yes), the reception data demodulator 15 performs despreading / BPSK demodulation processing (S46). As a result of the demodulation processing, the reception data demodulation unit 15 determines whether or not there is a synchronization word (S47). When there is no synchronization word (in the case of No), the intermittent reception is terminated (S50), and the process returns to S41.

  When there is a synchronization word (in the case of Yes), the reception data demodulator 15 performs a decoding process (data reception process) of user data (S48), determines whether or not the data reception is completed (S49), If not completed (in the case of No), the data reception process S48 is repeated. If the data reception is completed (in the case of Yes), the intermittent reception is terminated (S50), and the process returns to the process S41.

[Operation of conventional two-way radio system]
In the conventional bidirectional wireless system, since the primary modulation / demodulation is BPSK, when the frequency of the carrier for communication is more than a predetermined distance between the slave unit and the master unit, the master unit normally transmits the transmission data from the slave unit. Cannot receive.
Therefore, the master unit always executes FFT processing at the beginning of intermittent reception, grasps the frequency of the received data, matches its carrier frequency to the strongest frequency, and then performs SS-BPSK demodulation processing from the slave unit. Check if there is a transmission.

When data from the slave unit is received, the carrier frequency of the slave unit is detected as the strongest component by the FFT processing, so that the frequency synchronization with the slave unit is achieved by adjusting its own frequency to that frequency. be able to.
When transmitting data from the slave unit, CW (Cyclic Wave) data may be superimposed on the spread modulation signal and transmitted so that the master unit can detect its own carrier frequency.

[CW component superposition (no CW noise): FIG. 7]
Next, the case of transmitting the spread modulation signal with the CW component superimposed will be described with reference to FIG. FIG. 7 is a waveform diagram showing a normal case where the CW component is superimposed on the spread modulation signal.
As shown in FIG. 7, the normal case where the CW component is superimposed on the spread modulation signal is a case where there is no CW noise (CW noise) generated from another device.

  In order to make it easy for the master unit to detect the carrier frequency in the transmission data of the slave unit, the CW component is superimposed on the spread modulation signal and transmitted. When there is no CW noise in addition to the slave unit transmission data, the master unit detects the carrier frequency of the slave unit as a peak frequency and follows that frequency. As a result, the parent device can extract clean carrier demodulated data.

[CW component superposition (with CW noise): FIG. 8]
On the other hand, the case where there is CW noise will be described with reference to FIG. FIG. 8 is a waveform diagram showing an abnormal case where a CW component is superimposed on a spread modulation signal.
As shown in FIG. 8, when CW noise having a higher level than the transmission data of the slave unit is received, the master unit corrects the frequency. As a result, the difference from the slave carrier carrier frequency remains in the received data, and the correlation peak cannot be detected.

Incidentally, as a prior art for extracting a frequency hopping wave from various radio waves existing in a real space, there is Japanese Patent Laid-Open No. 2000-196503 “Reception Monitor Device” (Patent Document 1).
In Patent Document 1, the received signal is subjected to energy intensity analysis by an energy analysis circuit, converted into frequency channel-to-energy channel matrix data by a signal processing circuit, and the counter circuit counts the number of occurrences of the same data. It is shown that when the number of occupied frequency channels is the same as the occupied frequency channel number threshold “1”, it is determined as general communication, and when it is larger than “1”, it is determined as an FH (Frequency Hopping) communication wave. .

JP 2000-196503 A

  However, in the conventional bidirectional wireless system, when the CW component is superimposed on the spread modulation signal, if there is CW noise larger than the transmission power of the slave unit, the master unit detects the frequency of the CW noise as a peak frequency every time. Therefore, there is a problem that a correlation peak cannot be detected and a communication error occurs.

  In particular, CW noise may exist for a long period of time. Under such an environment, communication with the slave unit remains disconnected, resulting in a system failure.

  The present invention has been made in view of the above circumstances, and in a bidirectional radio system, when a CW component is superimposed on a spread modulation signal, a receiving circuit and a radio device capable of detecting a correlation peak even if CW noise is present The purpose is to provide.

The present invention for solving the problems of the above-described conventional example is a receiving circuit that performs intermittent reception with a radio device used in a bidirectional radio system, and removes a carrier component based on carrier data input from a received signal A carrier demodulator that outputs carrier demodulated data, a frequency detector that detects a peak frequency of the carrier demodulated data, a frequency correction process on a signal input from the frequency detector, and generates carrier data to generate a carrier demodulator A carrier data generation unit that outputs data, a correlation peak detection unit that detects correlation peaks for carrier demodulated data and outputs the presence or absence of correlation peak detection, a synchronization word is detected for carrier demodulation data, and data is decoded Input the peak frequency detected by the received data decoding unit that outputs the received data and the frequency detection unit, The presence or absence of correlation peak detection is input from the Seki peak detection unit, and when there is no correlation peak detection for the same peak frequency, if a specific number of times continues in intermittent reception, a designation for masking the peak frequency for a specific period is output to the frequency detection unit A frequency count / mask control unit, the frequency detection unit masks the peak frequency according to the designation, detects a peak frequency at a frequency other than the peak frequency, and the frequency count / mask control unit has the same peak frequency. A continuous counter that counts when there is no correlation peak detection until it reaches a specific number of consecutive receptions in intermittent reception, and a frequency mask that counts a specified frequency mask period by counting a specific number of times when intermittent reception occurs. And a carrier data generation unit And frequency correction to a first of the frequency detected by the wave number detecting unit, characterized in that frequency correction in the second frequency detected by the frequency detector in the frequency mask specification period.

In the receiving circuit according to the present invention, the frequency count / mask control unit sets the number of counts input from the outside in the continuous counter and the frequency mask designation period counter, stores the peak frequency detected by the frequency detection unit, When there is no correlation peak due to the presence or absence of correlation peak detection from the correlation peak detector, if the stored previous peak frequency is the same as the current peak frequency, an instruction to count up the continuous counter is output, and the previous peak is output. When the frequency and the current peak frequency are not the same, the count value of the continuous counter is cleared, and when the continuous counter finishes counting a specific number of times, a designation for masking the peak frequency for a specific period is output to the frequency detector, and the frequency Outputs an instruction to start counting with the mask specified period counter and counts the frequency mask specified period. When the count in the data is completed, characterized by having a control means for outputting a signal for releasing the designation.

  The present invention is characterized in that the wireless device includes the receiving circuit.

According to the present invention, there is provided a receiving circuit that performs intermittent reception with a radio device used in a bidirectional radio system, wherein carrier demodulation is performed by removing a carrier component based on carrier data input from a received signal by a carrier demodulating unit. The frequency detection unit detects the peak frequency of the carrier demodulation data, the carrier data generation unit performs frequency correction processing on the signal input from the frequency detection unit, generates carrier data, and outputs the carrier data to the carrier demodulation unit. The correlation peak detection unit detects the correlation peak for the carrier demodulated data, outputs the presence or absence of correlation peak detection, the received data decoding unit detects the synchronization word for the carrier demodulated data, performs the data decoding process, The received data is output, the frequency count / mask control unit inputs the peak frequency detected by the frequency detection unit, and the correlation peak When the presence or absence of correlation peak detection is input from the detection unit and there is no correlation peak detection for the same peak frequency, if a specific number of consecutive receptions occur in intermittent reception, the designation for masking the peak frequency for a specific period is output to the frequency detection unit. The detection unit masks the peak frequency in accordance with the designation, detects the peak frequency at a frequency other than the peak frequency, and the frequency count / mask control unit continuously performs the intermittent reception when no correlation peak is detected for the same peak frequency. A continuous counter that counts until a specific number of times is reached, and a frequency mask designation period counter that counts a frequency mask designation period by counting the specific number of times in intermittent reception when the specific number of times is reached. Is the first frequency detected by the frequency detector. Correct, the frequency mask specification period since the receiving circuit for frequency correction in the second frequency detected by the frequency detecting unit, even if there is CW noise or the like, there is an effect that can properly detect a correlation peak.

Embodiments of the present invention will be described with reference to the drawings.
[Outline of the embodiment]
The receiving circuit and the wireless device in the bidirectional wireless system according to the embodiment of the present invention detect the same frequency as the previous time every time intermittent reception is performed, and further count the number of times when no correlation peak is detected. In such a case, a process for masking the frequency for a predetermined time is performed, and the peak frequency is detected using the next strongest frequency in the other frequency band as the carrier frequency of the slave unit, and the correlation peak is detected. Normal carrier demodulated data can be extracted.

[Receiving circuit of master unit: Fig. 1]
The configuration of the receiving circuit of the master unit in the bidirectional radio system according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing the configuration of a receiving circuit of a master unit according to an embodiment of the present invention.
As shown in FIG. 1, a receiving circuit (main receiving circuit) of a base unit in a bidirectional radio system according to an embodiment of the present invention includes a carrier demodulating unit 11, an IF frequency detecting unit 12, and a carrier data generating unit 13. And a correlation peak detection unit 14, a reception data decoding unit 15, and a CW frequency count / mask control unit 20.

  The carrier demodulator 11 removes the IF carrier component from the input received IF signal, further performs down-sampling processing, and sends the IF frequency detector 12, the correlation peak detector 14, and the received data decoder 15. Outputs carrier demodulated data.

  The IF frequency detector 12 performs FFT processing on the carrier demodulated data input from the carrier demodulator 11 to detect the IF frequency (peak frequency), and outputs the IF frequency (peak frequency) to the carrier data generator 13 and the CW frequency count / mask controller 20. To do.

Further, when an instruction signal for specifying a specific frequency (frequency mask specification) is input from the CW frequency count / mask control unit 20, the IF frequency detection unit 12 ends the frequency mask specification period and cancels the specification. The frequency is masked until a signal is input.
That is, the IF frequency detection unit 12 masks the portion of the specific frequency (first peak frequency) with the frequency mask designation signal, detects the second peak frequency, and outputs the second peak frequency to the carrier data generation unit 13.

The carrier data generation unit 13 performs frequency correction processing according to the frequency detection result from the IF frequency detection unit 12 and generates IF carrier data to be supplied to the carrier demodulation unit 11.
The carrier data generation unit 13 normally generates carrier data so as to correct the own carrier frequency to the first frequency of FFT detection. However, when the frequency mask designation period is reached, the carrier data generation unit 13 sets the second carrier detection frequency to the second carrier detection frequency. The carrier data is generated so as to correct the frequency.
Therefore, when the frequency mask designation period ends, the carrier data generation unit 13 generates carrier data so as to correct the own carrier frequency to the first frequency of FFT detection.

  The correlation peak detection unit 14 performs correlation detection processing on the carrier demodulated data output from the carrier demodulation unit 11, performs correlation peak detection, and outputs the presence / absence of correlation peak detection to the CW frequency count / mask control unit 20. To do.

  The reception data decoding unit 15 performs despreading processing and BPSK demodulation processing after synchronization is established, detects a synchronization word, performs user data decoding processing (data reception processing), and outputs received data.

The CW frequency count / mask control unit 20 designates the number of consecutive CW counts and the number of frequency mask counts from the outside, and is set in an internal memory.
Further, the CW frequency count / mask control unit 20 inputs the frequency detection result from the IF frequency detection unit 12, inputs the presence / absence of correlation peak detection from the correlation peak detection unit 14, and sets the number of consecutive CWs and the frequency mask designation period. Counting is performed, and a frequency mask designation signal is output to the IF frequency detector 12. When the frequency mask designation period is counted, a designation cancellation signal is output.
Here, the number of continuous CWs and the count of the frequency mask designation period are incremented by one every time the receiving circuit performs an intermittent reception operation.

[CW frequency count / mask control unit: FIG. 2]
Next, the configuration of the CW frequency count / mask control unit 20 will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the CW frequency count / mask control unit.
As shown in FIG. 2, the CW frequency count / mask control unit 20 basically includes a control unit 21, a memory 22, a frequency mask designation period counter 23, and a continuous CW counter 24.
The control means 21 may be configured by hardware or may be realized by software processing.

The memory 22 stores the number of continuous CW counts and the number of frequency mask counts input from the outside via the control means 21.
The number of continuous CW counts is used to start masking of the continuous CW frequency when the number of consecutive CW counts in the absence of a correlation peak exceeds a specific value.
The frequency mask count is used to maintain the mask until the specific count is reached during the frequency mask designation.

The frequency mask designation period counter 23 sets the frequency mask count number by the control means 21 and counts the frequency mask designation period until the frequency mask count number is reached, that is, outputs an end signal to the control means 21 when the count is completed. To do.
Therefore, the frequency mask designation period counter 23 clears the count value when it finishes counting the frequency mask designation period.

The continuous CW counter 24 counts until the number of continuous CW counts is set by the control means 21, and there is no correlation peak and the same peak frequency as the previous time. Is output to the control means 21.
Therefore, when there is a correlation peak and when it is not the same peak frequency as the previous time, the continuous CW counter 24 clears the count value at the end of counting.

  The control means 21 inputs the number of continuous CW counts and frequency mask counts designated from the outside and stores them in the memory 22, and sets the frequency mask count times in the frequency mask designation period counter 23, and sets the continuous CW count times. Set to continuous CW counter 24.

  The control means 21 inputs the frequency detection result from the IF frequency detection unit 12 and the presence / absence of correlation peak detection from the correlation peak detection unit 14, and stores the peak frequency value of the frequency detection result in the memory 22. Then, when there is no correlation peak, the control means 21 compares the previous peak frequency with the current peak frequency, and if they are the same, instructs the count value of the continuous CW counter 24 to be +1 (counted up). If they are not the same, an instruction to clear the count value of the continuous CW counter 24 is output.

  Further, when the control means 21 inputs a count end (when the set number of times or more) end signal is received from the continuous CW counter 24, a frequency mask designation instruction signal for mask designation of the continuous CW frequency is given to the IF frequency detector 12. Output.

  The control means 21 outputs an instruction to increment the count value of the frequency mask designation period counter 23 every time intermittent reception is performed while the frequency mask is designated, and the count ends from the frequency mask designation period counter 23 (when the count is equal to or greater than the set count) ) End signal is output to the IF frequency detector 12 to clear the count value of the frequency mask designation period counter 23.

[Main unit intermittent reception processing flow: Figs. 3 and 4]
A process flow of intermittent reception in the base unit according to the embodiment will be described with reference to FIGS. FIG. 3 is a flowchart of the first half of the intermittent reception process in the base unit according to the embodiment, and FIG. 4 is a flowchart of the second half of the intermittent reception process in the base unit according to the embodiment.
3 (A) and 3 (B) are connected to the parts (A) and (B) of FIG. 4, respectively.

  As shown in FIG. 3, when reception processing is started in the parent device, the reception circuit of the parent device starts an intermittent reception operation (S11), and the carrier demodulation unit 11 removes the IF carrier component, and the IF frequency The detection unit 12 performs an FFT process to investigate the peak carrier frequency component (S12).

  Then, the IF frequency detection unit 12 determines whether or not an instruction signal for specifying a mask of a specific frequency is being input from the CW frequency count / mask control unit 20 (during frequency mask specification) (S13). If it is designated (in the case of Yes), the frequency detection result is output to the CW frequency count / mask control unit 20, and the CW frequency count / mask control unit 20 sets the count value of the frequency mask designation period counter 23 to +1 ( S14).

  The CW frequency count / mask control unit 20 determines whether or not the count value of the frequency mask designation period counter 23 is equal to or greater than the set count (S15). The carrier data generation unit 13 generates a carrier data frequency correction signal so as to correct the own carrier frequency to the second peak frequency (2nd peak frequency) of FFT detection (S16). As a result, the frequency is masked against CW noise.

  In addition, when the frequency mask is not specified in the determination process S13 (in the case of No) and when the number of count setting times is exceeded in the determination process S15 (in the case of Yes), the frequency mask specification period in the CW frequency count / mask control unit 20 The count value of the counter 23 is cleared (S17), and the carrier data generation unit 13 generates a carrier data frequency correction signal so as to correct the own carrier frequency to the first peak frequency (1st peak frequency) of FFT detection (S18). ).

Next, the correlation peak detector 14 performs processing for detecting a spread spectrum (SS) correlation peak (S19), and further determines the presence or absence of a correlation peak as shown in FIG. 4 (S20).
In the determination process S20, when there is a correlation peak (in the case of Yes), the count value of the continuous CW counter 24 in the CW frequency count / mask control unit 20 is cleared (S21), and the reception data demodulation unit 15 performs despreading / BPSK. Demodulation processing is performed (S22).

  As a result of the demodulation processing, the reception data demodulation unit 15 determines whether or not there is a synchronization word (S23). If there is no synchronization word (in the case of No), the intermittent reception is terminated (S31), and the process returns to S11.

  When there is a synchronization word (in the case of Yes), the reception data demodulator 15 performs a decoding process (data reception process) of user data (S24), determines whether or not the data reception is completed (S25), If not completed (in the case of No), the data reception process S24 is repeated. If the data reception is completed (in the case of Yes), the intermittent reception is terminated (S31), and the process returns to the process S11.

  In the determination process S20, when there is no correlation peak (in the case of No), the control means 21 in the CW frequency count / mask control unit 20 determines whether or not the peak frequency is the same as the previous time (S26). The control means 21 stores the value of the frequency in the memory 22 every time a frequency detection result is input from the IF frequency detection unit 12, and uses it for frequency comparison in the determination process S26.

  If it is not the same frequency as the previous time (in the case of No), the count value of the continuous CW counter 24 is cleared (S27). If it is the same frequency as the previous time (in the case of Yes), the count value of the continuous CW counter 24 is incremented by 1 (S28).

  Then, it is determined whether or not the count value of the continuous CW counter 24 is equal to or greater than the set number (S29). If the count value of the continuous CW counter 24 is not equal to or greater than the set number of times (in the case of No), the intermittent reception is terminated (S31), and the process returns to S11.

When the count value of the continuous CW counter 24 is equal to or greater than the set number of times (in the case of Yes), a designation instruction signal (frequency mask designation) for masking the continuous CW frequency is output to the IF frequency detector 12 (S30), and intermittent reception is performed The process ends (S31), and the process returns to S11.
As described above, the receiving process is performed by the receiving circuit in the master unit.

[Another embodiment]
In the CW frequency count / mask control unit 20 of FIG. 2, two counters, the frequency mask designation period counter 23 and the continuous CW counter 24, are provided. May be switched for use.

[Effect of the embodiment]
According to this receiving circuit, even in a CW noise generation environment, the next strongest level is corrected as the carrier frequency component from the slave unit during the period in which the frequency of the CW noise is masked, and thereafter reception is performed normally. There is an effect that can.

  The number of times until mask setting of the CW frequency and the period after masking are parameterized and stored in the memory 22 as a table corresponding to the application (application ID), and the corresponding parameter is used according to the request from the application to be activated. You may do it.

  Specifically, the application ID is output from the application to the control means 21, and the control means 21 reads a parameter or the like corresponding to the application ID from the table, and the read parameter or the like is read from the frequency mask designation period counter 23 and the continuous CW counter 24. Set to.

  The present invention is suitable for a bidirectional radio system capable of detecting a correlation peak even when CW noise is present when a CW component is superimposed on a spread modulation signal.

It is a block diagram of the configuration of the receiving circuit of the parent device according to the embodiment of the present invention. It is a block diagram of the configuration of a CW frequency count / mask control unit. It is a flowchart of the first half of the intermittent reception process in the parent device according to the embodiment. It is a flowchart of the latter half of the intermittent reception process in the parent device according to the embodiment. It is a block diagram showing a receiving circuit in a conventional base unit. It is a flowchart of the intermittent reception process in the conventional main | base station. It is a wave form diagram which shows the normal case where the CW component was superimposed on the spread modulation signal. It is a wave form diagram which shows the abnormal case which superimposed the CW component on the spread modulation signal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Carrier demodulation part, 12 ... IF frequency detection part, 13 ... Carrier data generation part, 14 ... Correlation peak detection part, 15 ... Reception data decoding part, 20 ... CW frequency count / mask control part, 21 ... Control means, 22 ... Memory, 23 ... Frequency mask designation period counter, 24 ... Continuous CW counter

Claims (3)

A receiving circuit that performs intermittent reception with a wireless device used in a bidirectional wireless system,
A carrier demodulator for removing carrier components based on carrier data input from the received signal and outputting carrier demodulated data;
A frequency detector for detecting a peak frequency for the carrier demodulated data;
A carrier data generation unit that performs frequency correction processing on a signal input from the frequency detection unit, generates carrier data, and outputs the carrier data to the carrier demodulation unit;
A correlation peak detector that detects a correlation peak for the carrier demodulated data and outputs the presence or absence of correlation peak detection;
A received data decoding unit that detects a synchronization word for the carrier demodulated data, performs data decoding processing, and outputs received data;
Input the peak frequency detected by the frequency detector, input the presence or absence of correlation peak detection from the correlation peak detector, and when there is no correlation peak detection for the same peak frequency, the peak A frequency count / mask control unit for outputting a designation for masking the frequency for a specific period to the frequency detection unit;
The frequency detector masks the peak frequency according to the designation, detects the peak frequency at a frequency other than the peak frequency ,
The frequency count / mask control unit counts when there is no correlation peak detection for the same peak frequency until the specific number of consecutive receptions in intermittent reception, and when the specific number of times is reached, the specific number of times in intermittent reception It has a frequency mask designation period counter that counts the frequency mask designation period by counting,
The carrier data generation unit corrects the frequency to the first frequency detected by the frequency detection unit, and corrects the frequency to the second frequency detected by the frequency detection unit during the frequency mask designation period. Receiving circuit. The frequency count / mask control unit sets the number of counts input from the outside in the continuous counter and frequency mask designation period counter, stores the peak frequency detected by the frequency detection unit, and detects the correlation peak from the correlation peak detection unit If there is no correlation peak from the presence or absence, and the stored previous peak frequency and the current peak frequency are the same, an instruction to count up the continuous counter is output, and the previous peak frequency and the current peak frequency When the count is not the same, the count value of the continuous counter is cleared, and when the continuous counter finishes counting a specific number of times, a designation for masking the peak frequency for a specific period is output to the frequency detection unit, and the frequency mask designation period Outputs an instruction to start counting with the counter, and the frequency mask designation period counter When the count is finished, the receiving circuit according to claim 1, wherein the control means for outputting a signal for releasing the designation. Radio, characterized in that it comprises a reception circuit according to claim 1 or 2, wherein.

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