JPWO2018092581A1 - transceiver - Google Patents

Abstract

A radio device capable of detecting interference is provided. The radio unit converts an analog signal of RF frequency, IF frequency, or baseband frequency into a digital signal, and frequency conversion that converts the digital signal output from the ADC from an RF frequency or IF frequency to a baseband frequency. A rate conversion unit that converts the signal output from the frequency conversion unit to a sampling rate that is optimal for demodulation processing, and optimizes the FFT result of the next process for the signal output from the rate conversion unit For this purpose, a window function unit for performing window processing, an FFT unit that converts a signal output from the window function unit into a relationship between frequency and level, and peak power of a carrier output from the FFT unit are detected, A first interference detection unit that determines an interference state based on the number of detected peaks.

Description

  The present disclosure relates to a wireless device, and can be applied to a receiver that performs interference detection, for example.

  Troubles due to interference are frequently reported in air traffic control wireless communications. Multiple radio stations transmit radio waves at the same frequency at the same time, causing interference on the receiving side. Conventional determination of presence / absence of interference is made by human ears. The air traffic control wireless communication system employs AM modulation, and in the state of interference, there is a voice cast or abnormal noise on the receiving side. Based on this, humans can identify the presence of interference and identify serious incidents. It has been prevented.

US Pat. No. 8,385,449 US Patent Application Publication No. 2016/0149737

  However, if there is a level difference of 20 dB or more in the reception level of multiple received radio waves, the influence of noise and noise caused by interference will be extremely small. Almost impossible. In addition, the conventional method of detecting interference causes a detection miss because it is judged only by hearing. Other problems and novel features will become apparent from the description of the specification and the accompanying drawings.

  The outline of a representative one of the present disclosure will be briefly described as follows. That is, the radio unit converts the analog signal of the RF frequency, IF frequency, or baseband frequency into a digital signal, and the baseband frequency if the digital signal output from the ADC is an RF frequency or IF frequency. A first rate conversion unit that converts a signal output from the frequency conversion unit or a signal output from the ADC to an optimum sampling rate for demodulation processing, and a signal output from the first rate conversion unit. An AGC unit that amplifies or attenuates the amplitude to an optimum level for AM demodulation, a demodulator that demodulates the signal output from the AGC unit into an audio signal, and a digital signal that is a demodulation result of the demodulator is converted into an analog signal A DAC to be converted, a second rate conversion unit for further rate-converting the signal output from the first rate conversion unit, A window function unit for applying window processing to optimize the FFT result of the next processing on the signal output from the two-rate conversion unit, and the signal output from the window function unit with frequency and level An FFT unit that converts the relationship into a relationship; and a first interference detection unit that detects the peak power of the carrier output from the FFT unit and determines an interference state based on the number of detected peaks.

  According to the wireless device, interference can be detected.

System diagram of digital processing circuit of radio according to the embodiment FIG. 1 is a processing flowchart showing the operation of the digital processing circuit of FIG. Simulation waveform diagram of spectrum without interference Simulation waveform diagram of signal without interference Waveform simulation waveform diagram with interference Simulation waveform diagram of signal when there is interference Diagram showing phase and power with and without interference and their amount of change Voice pitch extraction waveform diagram with and without interference

  In wireless communication, multiple wireless stations transmit radio waves at the same frequency at the same time, causing interference on the receiving side. The wireless device according to the embodiment determines whether or not there is interference in one or a plurality of methods with respect to the received radio wave and notifies it. More specifically, in the embodiment, a weak received signal that cannot be identified by human hearing is detected by digital processing, the presence or absence of interference is determined, and notification is made. Furthermore, multiple detection methods of interference are implemented and the results are combined to make up for the respective disadvantages and reduce false detections and missed detections. At the same time, the output voice and power level fluctuations are also used as information for judging the presence or absence of interference.

  Examples will be described below with reference to the drawings. However, in the following description, the same components may be denoted by the same reference numerals and repeated description may be omitted.

  FIG. 1 is a system diagram of a digital processing circuit of a wireless device according to an embodiment. FIG. 2 is a flowchart showing the operation of the digital processing circuit of FIG.

  A receiver 100 which is a radio device includes an analog / digital converter (ADC) 2 to which an analog signal 1 is input, a frequency converter (F_CONV) 3, a first rate converter (R_CONV) 4, and automatic gain control. (Automatic Gain Control: AGC) section 5, demodulation section 6, and digital / analog conversion section (DAC) 26 that outputs audio signal 7.

The receiver 100 further includes a second rate conversion unit 8 to which a signal from the first rate conversion unit 4 is input, a window function unit 9, a fast Fourier transform (FFT) unit 10, The receiver 100 including the interference detection unit 11 further includes a third rate conversion unit 12 to which a signal from the first rate conversion unit 4 is input, a phase detection unit 13, and a first change amount calculation unit 14. , A detection unit 15, a second change amount calculation unit 16, and a second interference detection unit 17.

  The receiver 100 further includes a fourth rate conversion unit 18, a voice analysis unit 19, and a third interference detection unit 20.

  The receiver 100 further includes an interference determination unit 21 to which the interference determination results of the first interference detection unit 11, the second interference detection unit 17, and the third interference detection unit 20 are input.

  The receiver 100 further includes a power detection unit 24 to which signals output from the FFT unit 10 and the first rate conversion unit 4 are input.

Next, the operation of the receiver 100 will be described. Note that the step numbers in FIG. 2 (numbers following “S”) correspond to the numbers of the constituent elements in FIG.
Step S2: The ADC 2 converts the analog signal 1 having the IF frequency or the analog signal 1 having the orthogonalized baseband frequency into a digital signal.
Step S3: The frequency converter 3 converts the digital signal output from the ADC 2 from the IF frequency to the baseband frequency. However, when the orthogonalized analog signal of the baseband frequency is converted into a digital signal by the ADC 2, the frequency converter 3 (step S3) can be omitted.
Step S4: The first rate conversion unit (R_CONV) 4 converts the signal output from the frequency conversion unit 3 into a sampling rate optimum for demodulation processing.
Step S5: The AGC unit 5 amplifies or attenuates the amplitude of the signal output from the first rate conversion unit 4 to a level optimal for AM demodulation.
Step S5: The demodulator 6 demodulates the signal output from the AGC unit 5 into an audio signal.

  Step S26: The DAC 26 converts the digital signal as the demodulation output result into the audio signal 7 which is an analog signal.

The above operations are normal receiver operations. Next, the first interference detection operation will be described.
Step S8: The second rate conversion unit 8 further performs rate conversion on the signal output from the first rate conversion unit 4.
Step S9: The window function unit 9 performs window processing on the signal output from the second rate conversion unit 8 in order to optimize the FFT result of the next processing.
Step S10: The FFT unit 10 converts the signal output from the window function unit 9 into a relationship between frequency and level.
Step S11: The first interference detection unit 11 detects the peak power of the carrier output from the FFT unit 10, and determines the interference state based on the number of detected peaks.

  If the FFT size is fixed, the frequency resolution of the FFT can be improved by narrowing the sampling frequency of the received signal further than the band necessary for demodulation. This is determined by the frequency deviation of the transmitter. The sampling frequency is adjusted so that the frequency resolution of the FFT can identify fluctuations in the transmission frequency of the radio, and the FFT processing is performed to calculate the relationship between the frequency and the reception level. The number of peak powers, which are carrier components of the modulation signal, is detected from the FFT output. If the number of peak powers above a certain threshold is two or more, it is determined that there is interference. In this process, in order not to detect a minute level increase or decrease of the noise floor as peak power, a threshold is set so that only peak power above a certain level is detected. This threshold value can be arbitrarily changed by the external signal 23 according to the radio wave reception status (radio wave status).

  FIG. 3 is a spectrum simulation waveform diagram showing an enlarged display of a carrier signal of an AM modulated wave when there is no interference. FIG. 4 is an FFT simulation waveform diagram when there is no interference. By reducing the sampling frequency to several hundred hertz, only the carrier signal of the AM modulated wave can be extracted. The peak output of the carrier signal is one.

  FIG. 5 is a spectrum simulation waveform diagram showing an enlarged display of a carrier signal of an AM modulated wave when there is interference. FIG. 6 is an FFT simulation waveform diagram when there is interference. When interference occurs, even if the transmitting side transmits at the same frequency, multiple AM modulated wave carrier signals can be confirmed on the receiving side due to the fluctuation of the original oscillation and the Doppler shift. In this process, the peak power of the carrier signal is detected, and if there are two or more peak powers higher than a certain threshold, it is determined that interference has been detected. However, if the carrier frequency of the AM modulated wave is very close, the carrier signal of the AM modulated wave may overlap each other on the frequency axis, which may cause a missed detection of peak power.

Next, the second interference detection operation will be described.
Step S12: The third rate conversion unit 12 further performs rate conversion on the signal output from the first rate conversion unit 4.
Step S13: The phase detector 13 calculates the phase of the signal output from the third rate converter 12.
Step S14: The first change amount calculation unit 14 obtains the change amount of the signal output from the phase detection unit 13.
Step S15: The detector 15 calculates the power of the signal output from the third rate converter 12.
Step S16: The second change amount calculation unit 16 obtains the change amount of the signal output from the detection unit 15.
Step S <b> 17: The second interference detection unit 17 comprehensively determines the interference state from the results of detection of the change amounts of the first change amount calculation unit 14 and the second change amount calculation unit 16.

  The second interference detection unit 17 adjusts the sampling frequency of the received signal as in the first interference detection operation, and calculates either the phase or power of the carrier, or both. Further, the calculated carrier phase and power variation are calculated. If there is interference, both of the calculated changes will have a peak value of change compared to when there is no interference, so it will be judged as interference if the peak exceeds a certain threshold. It is desirable to detect both power and phase because the amount of change in the presence or absence of interference may be reduced due to the level difference or phase difference of multiple received signals. This threshold value can be arbitrarily set by the external signal 23 according to the radio wave reception status.

  FIG. 7 is a diagram showing the received power amount (A), phase (B), received power change amount (C), and phase change amount (D) with and without interference. Similar to the first interference detection operation, the second interference detection unit 17 can extract only the carrier signal of the AM modulated wave by lowering the sampling frequency to the order of several hundred hertz. When the carrier frequencies of multiple AM modulation waves are very close to each other, such as 1 Hz or less, as shown by the circles in the figure, the received power changes after the pulses are generated in the received power change amount and the phase change amount. The difference frequency appears in each signal of the amount of change and phase change. If the fluctuation amount (blurring) of these signals is greater than a certain threshold, the interference judgment block is notified as interference detection.

Next, a third interference detection operation will be described.
Step S18: The fourth rate converter 18 further performs rate conversion on the demodulation result output from the demodulator 6.
Step S19: The voice analysis unit 19 performs voice analysis on the signal output from the fourth rate conversion unit 18.
Step S20: The third interference detection unit 20 detects the presence or absence of interference from the voice analysis result output from the voice analysis unit 19.

  The third interference detection unit 20 detects the presence or absence of interference by adjusting the sampling frequency of the demodulation result output from the demodulation unit 6, performing voice analysis, and detecting whether there are a plurality of speakers. There are various methods for speech analysis, such as waveform processing, correlation processing, and spectrum processing. The most appropriate method is determined according to the configuration and purpose of use of the radio. For example, by the pitch extraction method, it is possible to detect whether there are multiple speakers in the speech, that is, the presence or absence of interference, based on how the peaks in the output of the autocorrelation calculation in a specific speech interval. .

  In addition, as a method of different voice analysis, for voice communication using call signs and phonetic codes determined by air traffic control, it has multiple matched filters with different voice pitches for every call sign, and demodulation By performing a convolution operation with the voice signal thus generated, correlation peaks of multiple call signs occur during interference, and the presence or absence of interference can be determined by detecting this. The detection and determination algorithm can be set and changed by the external signal 23.

  FIG. 8 shows the voice signal (A) of the speaker A, the spectrum (B) of the short voice signal of the speaker A, the voice signal (C) of the speaker B, and the spectrum (D) of the short voice signal of the speaker B. FIG. 5 is a waveform diagram showing a spectrum (F) of a voice signal (E) obtained by synthesizing speaker A and speaker B and a short-distance voice signal of a voice signal obtained by synthesizing speaker A and speaker B. In the voice signal spectrum (B) of the speaker A and the voice signal spectrum (D) of the speaker B, the peak power stands at a constant interval pitch on the frequency axis. On the other hand, in the voice signal spectrum (F) obtained by synthesizing the voices of the speaker A and the speaker B, the peak power is generated at different pitches due to the plurality of speakers, and the pitch deviation can be confirmed. By detecting the pitch deviation, interference is detected and notified to the interference determination block.

  Next, the final determination of interference detection by the first interference detection unit, the second interference detection unit, and the third interference detection unit will be described.

  Step S21: The interference determination unit 21 performs a final determination of interference detection based on the interference detection results of the first interference detection operation, the second interference detection operation, and the third interference detection operation, and the determination result ( An interference determination result output signal 22) is output. Interference detection methods differ in the detection result update cycle, accuracy, and detection range depending on the processing method and processing amount. For example, the method of detecting the power peak of the FFT output in the first interference detection operation can detect the presence or absence of interference accurately by detecting subtle deviations in the transmission frequency of each transmitter. If the frequencies are close, detection may be missed. Depending on the relationship between the sampling frequency and the number of FFT points, the method for detecting the power peak at the FFT point in the first interference detection operation may take several seconds to detect. On the other hand, it is possible to detect the amount of change in the second interference detection operation. The detection results of these three methods are combined to obtain the final interference determination output. Although the final interference judgment is performed by combining the detection results of the three methods, any two of the three or one interference judgment may be used. In that case, there is no need to use a circuit that is not used for the determination.

  Interference causes a beat (waveform fluctuation) depending on the power difference between the modulated waves. The power detection unit 24 detects the power difference between the two modulated waves from the fluctuation amount of the beat and notifies it as an interference level output 25. Since the interference level can be determined from the power difference, the operator (human) may be used as the final determination result in addition to the interference determination result in step S21. When not used for final determination, the power detection unit 24 may not be provided.

  According to the embodiment, it is possible to reduce detection misses that frequently occur in interference detection using human hearing. As an example, if there is interference in air traffic in air traffic control, air traffic control information cannot be exchanged between multiple senders and receivers, and in the worst case, a serious incident occurs. The embodiment reduces interference detection misses and false detections, and, as an example, leads to avoidance of serious incidents in air traffic control.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and needless to say, various modifications can be made.

  INDUSTRIAL APPLICABILITY The present invention can be used for radio communication and radio communication systems for air traffic control at an airfield, and can be used for detection of interference when a plurality of radio stations transmit and transmit radio waves at the same frequency. This application claims the benefit of priority based on Japanese Patent Application No. 2006-223195 filed on Nov. 16, 2016, the entire disclosure of which is incorporated herein by reference.

  DESCRIPTION OF SYMBOLS 1 ... Analog signal, 2 ... ADC, 3 ... Frequency conversion part, 4 ... 1st rate conversion part, 5 ... AGC part, 6 ... Demodulation part, 7 ... Audio | voice signal, 8 ... Second rate conversion part, 9 ... Window Function part, 10 ... FFT part, 11 ... First interference detection part, 12 ... Third rate conversion part, 13 ... Phase detection part, 14 ... First change amount calculation part, 15 ... Detection part, 16 ... Second change Amount calculation unit, 17 ... second interference detection unit, 18 ... fourth rate conversion unit, 19 ... voice analysis unit, 20 ... third interference detection unit, 21 ... interference determination unit, 22 ... interference determination result output signal, 23 ... External signal, 24 ... power detector, 25 ... interference level output, 100 ... receiver

Claims (6)

An ADC that converts an analog signal of RF frequency, IF frequency or baseband frequency into a digital signal;
A digital signal output from the ADC is converted from an RF frequency or IF frequency to a baseband frequency, and a signal output from a frequency converter or a signal output from the ADC is converted to a sampling rate optimum for demodulation processing. A rate converter,
An AGC unit that amplifies or attenuates the amplitude of the signal output from the first rate conversion unit to a level optimum for AM demodulation;
A demodulator that demodulates the signal output from the AGC unit into an audio signal;
A DAC that converts a digital signal of a demodulation result of the demodulation unit into an analog signal;
A second rate conversion unit for further rate converting the signal output from the first rate conversion unit;
A window function unit for applying window processing to optimize the FFT result of the next processing on the signal output from the second rate conversion unit;
An FFT unit for converting a signal output from the window function unit into a relationship between frequency and level;
A first interference detection unit that detects a peak power of a carrier output from the FFT unit and determines an interference state based on the number of detected peaks. The claim 1, further comprising:
A third rate conversion unit for further rate converting the signal output from the first rate conversion unit;
A phase detector that calculates the phase of the signal output from the third rate converter;
A first change amount calculation unit for obtaining a change amount of the signal output from the phase detection unit;
A detector for calculating the power of the signal output from the third rate converter;
A second change amount calculation unit for obtaining a change amount of the signal output from the detection unit;
A second interference detection unit that determines an interference state based on a detection result of each change amount of the first change amount calculation unit and the second change amount calculation unit;
A radio apparatus comprising: an interference determination unit that determines the presence or absence of interference based on the interference determination result of the first interference detection unit and the interference determination result of the second interference detection unit. The claim 1, further comprising:
A fourth rate conversion unit for further rate converting the demodulation result output from the demodulation unit;
A voice analysis unit for voice analysis of the signal output from the fourth rate conversion unit;
A third interference detection unit that detects the presence or absence of interference from the voice analysis result output from the voice analysis unit;
And a radio interference determination unit that determines the presence or absence of interference based on the interference determination result of the first interference detection unit and the interference determination result of the third interference detection unit. The claim 1, further comprising:
A third rate conversion unit for further rate converting the signal output from the first rate conversion unit;
A phase detector that calculates the phase of the signal output from the third rate converter;
A first change amount calculation unit for obtaining a change amount of the signal output from the phase detection unit;
A detector for calculating the power of the signal output from the third rate converter;
A second change amount calculation unit for obtaining a change amount of the signal output from the detection unit;
A second interference detection unit that determines an interference state based on a detection result of each change amount of the first change amount calculation unit and the second change amount calculation unit;
A fourth rate conversion unit for further rate converting the demodulation result output from the demodulation unit;
A voice analysis unit for voice analysis of the signal output from the fourth rate conversion unit;
A third interference detection unit that detects the presence or absence of interference from the voice analysis result output from the voice analysis unit;
An interference determination unit that determines the presence or absence of interference based on the interference determination result of the first interference detection unit, the interference determination result of the second interference detection unit, and the interference determination result of the third interference detection unit; . In any one of Claims 1 thru | or 4, Furthermore,
A radio comprising a power detection unit that detects a level of interference from a plurality of power or voltage level fluctuations based on signals output from the FFT unit and the first rate conversion unit. In any one of Claims 1 thru | or 4,
A radio that enables setting of a detection threshold value or an algorithm of the first interference detection unit, the second interference detection unit, or the third interference detection unit.

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