JP6103951B2 - Radar apparatus and radar signal receiving method - Google Patents

Description

  The present invention relates to a radar apparatus and a radar signal receiving method.

  The radar device is a radar device that transmits and receives a radar signal by using the same pulse modulation reference signal and the output signal of the local oscillator on the transmission side and the reception side. There are independent radar devices using a pulse modulation reference signal and an output signal of a local oscillator.

JP-A-2-236480

  Since the radar apparatus disclosed in Patent Document 1 uses the pulse modulation reference signal and the output signal of the local oscillator that are independent on the transmission side and the reception side, the frequency variation of the pulse modulation reference signal and the output signal of the local oscillator on the reception side. Is detected from the output filter of the FFT filter at the time of direct wave reception from the transmitting station to the receiving station. Then, based on the detection result, the output of the FFT filter is selected, the clutter is removed, and only the signal reflected on the moving target is extracted. Since the radar apparatus disclosed in Patent Document 1 includes a frequency shift detector and the like for detecting frequency fluctuations, the configuration of the apparatus is complicated.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to simplify a configuration for receiving a radar signal.

In order to achieve the above object, a radar apparatus according to the present invention is a radar apparatus that retains information related to a pulse repetition period of a radar signal, and includes an antenna, an amplifier, an A / D converter, an oscillator, an adjustment unit, and a phase detector. And a frequency detector. Antenna is pulse-modulated by the pulse modulation reference signal, a local signal whose pulse repetition local oscillator of a predetermined frequency transmitted at the same timing as the period is outputted is a signal reflected by the target, receiving the radar signal . The amplifier amplifies the radar signal. The A-D converter samples the amplified radar signal at a predetermined sampling frequency. Oscillator outputs a reception-side pulse modulation reference signal to a frequency difference is equal to or smaller than the threshold value of a value obtained by adding the frequency of the pulse modulation reference signal of the local signal. The adjusting unit adjusts the phase of the reception side pulse modulation reference signal by matching the phase reference of the reception side pulse modulation reference signal with the start time of the pulse repetition period . The phase detector is configured to detect the phase of the radar signal sampled by the AD converter based on the reception side pulse modulation reference signal adjusted by the adjustment unit and the signal obtained by shifting the phase of the reception side pulse modulation reference signal by 90 degrees. To output an I signal and a Q signal. The frequency detector detects the Doppler frequency from the I signal and the Q signal.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to simplify the structure which receives a radar signal.

It is a block diagram which shows the structural example of the radar apparatus which concerns on Embodiment 1 of this invention. 6 is a diagram illustrating an example in which the phase reference of the receiving side COHO signal is adjusted to a predetermined timing in the radar apparatus according to Embodiment 1. FIG. 4 is a flowchart illustrating an example of a signal reception operation performed by the radar apparatus according to the first embodiment. It is a block diagram which shows the structural example of the radar apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structural example of the radar apparatus which concerns on Embodiment 3 of this invention. 10 is a flowchart illustrating an example of a signal reception operation performed by the radar apparatus according to the third embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent parts are denoted by the same reference numerals.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration example of a radar apparatus according to Embodiment 1 of the present invention. The radar apparatus 1 includes an antenna 2, a transmission-side oscillator 3, a local oscillator 4, a UC (Up-Converter) unit 5, a transmission / reception switching unit 6, an RF (Radio Frequency) amplifier 7, an AD (Analog-). Digital) converter 8, receiving oscillator 9, adjustment unit 10, phase detector 11, and frequency detector 12.

  Processing on the transmission side will be described. The transmission-side oscillator 3, which is a transmission-side coherent oscillator, sends a pulse modulation reference signal (hereinafter referred to as a COHO signal) to the UC unit 5. The local oscillator 4 sends a local signal to the UC unit 5. The UC unit 5 generates a radar signal by pulse-modulating the local signal with the COHO signal, and transmits the radar signal at a predetermined timing via the transmission / reception switching unit 6 and the antenna 2.

  Processing on the receiving side will be described. The antenna 2 receives the radar signal transmitted at a predetermined timing and reflected by the target, and sends the radar signal to the RF amplifier 7 via the transmission / reception switching unit 6. The RF amplifier 7 amplifies the received radar signal and sends it to the AD converter 8. The AD converter 8 samples the amplified radar signal at a predetermined sampling frequency, and sends the sampled radar signal to the phase detector 11.

  The receiving-side oscillator 9 has a difference between a value obtained by adding the frequency of the local signal and the frequency of the COHO signal equal to or smaller than a threshold value, or a difference between a value obtained by subtracting the frequency of the local signal and the frequency of the COHO signal from the sampling frequency. A reception side pulse modulation reference signal (hereinafter referred to as a COHO ′ signal) having a frequency equal to or smaller than a threshold value is sent to the phase detector 11. The threshold is set to a sufficiently small value, and the frequency of the COHO 'signal matches the value obtained by adding the frequency of the local signal and the frequency of the COHO signal, or the value obtained by subtracting the frequency of the local signal and the frequency of the COHO signal from the sampling frequency. Then, it is preferable that it can be considered. The reception-side oscillator 9 is an oscillator independent of the transmission-side oscillator 3, and the frequency is determined based on the known local signal frequency and the COHO signal frequency.

  The frequency of the COHO signal is fc, the frequency of the local signal is fs, the Doppler frequency is fd, the frequency of the radar signal sampled by the AD converter 8 is fad, and the Doppler frequency is removed from the frequency of the sampled radar signal. Let the component be fad ′. The frequency of the sampled radar signal is fad = fad ′ + fd. When sampled at a frequency equal to or higher than the Nyquist frequency, the original signal can be restored and can be expressed as fad '= fs + fc. In this case, the receiving-side oscillator 9 outputs COHO ′ having a frequency whose value is a difference between the frequency of the local signal and the value obtained by adding the frequencies of the COHO signal is equal to or less than a threshold value. If the frequency of COHO ′ is fc ′, then fc′≈fs + fc.

  The sampled radar signal Sad is expressed by the following equation (1). In the following formula (1), f is a frequency, A is an amplitude, and φ is a phase difference caused by reflection of a radar signal on a target.

  The phase detector 11 branches the sampled radar signal Sad into two systems, detects one with a COHO ′ signal having a frequency of fad ′, and detects the other with a signal obtained by shifting the phase of the COHO ′ signal by 90 degrees. Thus, the I signal and the Q signal are generated and output. By phase detection, the component of frequency fad 'is removed, and signals of A'cosφ and A'sinφ are obtained. However, A 'is the amplitude of the signal after phase detection.

  When sampled at a frequency lower than the Nyquist frequency, the original signal cannot be restored. If the sampling frequency is fsam, it can be expressed as fad '= fsam- (fs + fc). In this case, the receiving-side oscillator 9 outputs COHO ′ having a frequency that is a difference between the sampling frequency and the value obtained by subtracting the frequency of the COHO signal from the sampling frequency. When the frequency of COHO ′ is fc ′, fc′≈fsam− (fs + fc).

  Similarly to the above case, the phase detector 11 branches the sampled radar signal Sad into two systems, detects one with a COHO ′ signal having a frequency of fad ′, and detects the other with the phase of the COHO ′ signal being 90 °. By detecting with the shifted signal, I signal and Q signal are generated and output.

  The frequency detector 12 detects the Doppler frequency from the I signal and the Q signal, and outputs it to an external device. Based on the Doppler frequency, the speed of the target can be detected.

  The adjustment unit 10 adjusts the phase of the COHO ′ signal. For example, the adjusting unit 10 adjusts the phase reference of the COHO ′ signal at a predetermined timing at which the radar signal is transmitted. The phase reference is, for example, that the phase is 0 when the phase changes from minus to plus.

  FIG. 2 is a diagram illustrating an example in which the phase reference of the receiving-side COHO signal is adjusted to a predetermined timing in the radar apparatus according to the first embodiment. The dotted line is the timing at which the radar signal is transmitted, and the receiving side holds information about the transmission timing. As shown in the upper part of FIG. 2, the transmission side transmits pulses at an interval of PRI (Pulse Repetition Interval). On the receiving side, as shown in the middle part of FIG. 2, the pulse reflected by the target is received. As shown in the lower part of FIG. 2, the adjustment unit 10 matches the phase reference of the COHO ′ signal with the timing at which the radar signal is transmitted.

  Since the PRI is a sufficiently short time, a value obtained by adding the frequency of the COHO ′ signal, the frequency of the local signal, and the frequency of the COHO signal by matching the phase reference of the COHO ′ signal to the start time of the PRI for each PRI. Alternatively, the deviation between the sampling frequency and the value obtained by subtracting the frequency of the local signal and the frequency of the COHO signal can be minimized. The COHO ′ signal adjusted by the adjusting unit 10 is input to the phase detector 11, and phase detection is performed using the COHO ′ signal, thereby generating an I signal and a Q signal and detecting a Doppler frequency. Become.

  FIG. 3 is a flowchart illustrating an example of a signal reception operation performed by the radar apparatus according to the first embodiment. The antenna 2 receives the radar signal transmitted at a predetermined timing and reflected by the target (step S110). The RF amplifier 7 amplifies the received radar signal (step S120). The A-D converter 8 samples the amplified radar signal at a predetermined sampling frequency (step S130). The phase detector 11 branches the sampled radar signal Sad into two systems, detects one with the COHO ′ signal adjusted by the adjusting unit 10, and detects the other with a signal obtained by shifting the phase of the COHO ′ signal by 90 degrees. Thus, an I signal and a Q signal are generated (step S140). The frequency detector 12 detects the Doppler frequency from the I signal and the Q signal (step S150).

  Since the radar apparatus 1 according to the first embodiment uses independent oscillators on the transmission side and the reception side, it is not necessary to make the same signal available on the transmission side and the reception side, and the configuration of the radar apparatus 1 is simple. It becomes. Further, since the radar signal in the RF region is directly sampled by the A / D converter 8, it is not necessary to provide an IF mixer or the like, and the configuration of the radar apparatus 1 can be simplified. It is also possible to divide the arrangement on the transmitting side and the receiving side and use it as a bistatic radar.

  As described above, according to the radar apparatus 1 according to the first embodiment, the configuration for receiving radar signals can be simplified.

(Embodiment 2)
FIG. 4 is a block diagram showing a configuration example of a radar apparatus according to Embodiment 2 of the present invention. The radar apparatus 1 according to the second embodiment has the same configuration as that of the radar apparatus 1 according to the first embodiment shown in FIG. 1 except that the COHO signal and the local signal are shared between the transmission side and the reception side.

  The adjusting unit 10 adjusts the phase of the COHO ′ signal based on the COHO signal and the local signal. The adjustment unit 10 is configured such that the frequency of the COHO ′ signal matches the value obtained by adding the frequency of the local signal and the frequency of the COHO signal, or the frequency of the COHO ′ signal is a value obtained by subtracting the frequency of the local signal and the frequency of the COHO signal from the sampling frequency. The phase of the COHO ′ signal is adjusted so that

  The signal reception operation of the radar apparatus 1 according to the second embodiment is the same as that of the radar apparatus 1 according to the first embodiment shown in FIG.

  In the radar apparatus 1 according to the second embodiment, the radar signal in the RF region is directly sampled by the A / D converter 8, so that it is not necessary to provide an IF mixer or the like, and the configuration of the radar apparatus 1 can be simplified. Is possible.

  As described above, according to the radar apparatus 1 according to the second embodiment, the configuration for receiving radar signals can be simplified.

(Embodiment 3)
FIG. 5 is a block diagram showing a configuration example of a radar apparatus according to Embodiment 3 of the present invention. The radar apparatus 1 according to the third embodiment has the same configuration as the radar apparatus 1 according to the first embodiment shown in FIG. 1 except that the COHO signal and the local signal are shared on the transmission side and the reception side.

  The adjustment unit 10 detects an error included in the COHO ′ signal based on the COHO signal, the local signal, and the COHO ′ signal. That is, the phase difference between the signal whose frequency is fs + fc and the COHO ′ signal is detected and sent to the frequency detector 12.

  The phase detector 11 branches the sampled radar signal Sad into two systems, one is detected by the COHO ′ signal, and the other is detected by a signal in which the phase of the COHO ′ signal is shifted by 90 degrees, whereby the I signal and Generate and output Q signal. By phase detection, the component of frequency fad 'is removed, and signals of A'cosφ and A'sinφ are obtained. However, A 'is the amplitude of the signal after phase detection.

  The frequency detector 12 corrects the phases of the I signal and the Q signal based on the error detected by the adjusting unit 10, detects the Doppler frequency from the corrected I signal and the Q signal, corrects the Doppler frequency, Output to the device.

  FIG. 6 is a flowchart illustrating an example of a signal reception operation performed by the radar apparatus according to the third embodiment. The processing in steps S110 to S140 is the same as the operation performed by the radar apparatus 1 according to the first embodiment shown in FIG. The adjusting unit 10 detects an error included in the COHO ′ signal based on the COHO signal, the local signal, and the COHO ′ signal (step S141). The frequency detector 12 corrects the phases of the I signal and the Q signal based on the error included in the COHO ′ signal detected by the adjustment unit 10, and detects the Doppler frequency from the corrected I signal and Q signal (step S160). Note that the process of step S140 and the process of step S141 may be executed in parallel.

  In the radar apparatus 1 according to the third embodiment, the radar signal in the RF region is directly sampled by the A / D converter 8, so that it is not necessary to provide an IF mixer or the like, and the configuration of the radar apparatus 1 can be simplified. Is possible.

  As described above, according to the radar apparatus 1 according to the third embodiment, the configuration for receiving radar signals can be simplified.

  The embodiment of the present invention is not limited to the above-described embodiment.

  DESCRIPTION OF SYMBOLS 1 Radar apparatus, 2 Antenna, 3 Transmission side oscillator, 4 Local oscillator, 5 U-C part, 6 Transmission / reception switching part, 7 RF amplifier, 8 AD converter, 9 Reception side oscillator, 10 Adjustment part, 11 Phase detection Instrument, 12 frequency detector.

Claims (10)

A radar device that holds information about a pulse repetition period of a radar signal,
Is pulse-modulated by the pulse modulation reference signal is a signal in which the local signal is reflected in the target the local oscillator of a predetermined frequency transmitted at the same timing as the pulse repetition period is output, an antenna for receiving radar signals ,
An amplifier for amplifying the radar signal;
An A / D converter that samples the amplified radar signal at a predetermined sampling frequency;
An oscillator that outputs a reception-side pulse modulation reference signal having a frequency that is a difference between a frequency of the local signal and a value obtained by adding the frequency of the pulse modulation reference signal equal to or less than a threshold;
An adjustment unit that adjusts the phase of the reception-side pulse modulation reference signal by matching the phase reference of the reception-side pulse modulation reference signal with the start time of the pulse repetition period ;
Based on the reception side pulse modulation reference signal adjusted by the adjustment unit and a signal obtained by shifting the phase of the reception side pulse modulation reference signal by 90 degrees, phase detection of the radar signal sampled by the AD converter is performed. A phase detector for performing and outputting I and Q signals;
A frequency detector for detecting a Doppler frequency from the I signal and the Q signal;
A radar apparatus comprising:   A radar device that holds information about a pulse repetition period of a radar signal,
  An antenna that receives a radar signal, which is a pulse signal modulated by a pulse modulation reference signal, and a local signal output from a local oscillator of a predetermined frequency that is transmitted at the same timing as the pulse repetition period is a signal reflected by a target;
  An amplifier for amplifying the radar signal;
  An A / D converter that samples the amplified radar signal at a predetermined sampling frequency;
  An oscillator that outputs a reception side pulse modulation reference signal having a frequency that is a difference between a value obtained by subtracting the frequency of the local signal and the frequency of the pulse modulation reference signal from the sampling frequency, which is equal to or less than a threshold;
  An adjustment unit that adjusts the phase of the reception-side pulse modulation reference signal by matching the phase reference of the reception-side pulse modulation reference signal with the start time of the pulse repetition period;
  Based on the reception side pulse modulation reference signal adjusted by the adjustment unit and a signal obtained by shifting the phase of the reception side pulse modulation reference signal by 90 degrees, phase detection of the radar signal sampled by the AD converter is performed. A phase detector for performing and outputting I and Q signals;
  A frequency detector for detecting a Doppler frequency from the I signal and the Q signal;
  A radar apparatus comprising: The adjustment unit adjusts the phase of the reception-side pulse modulation reference signal to match the frequency of the reception-side pulse modulation reference signal with a value obtained by adding the frequency of the local signal and the frequency of the pulse modulation reference signal. The radar apparatus according to claim 1.   The adjusting unit adjusts the phase of the reception-side pulse modulation reference signal, and subtracts the frequency of the reception-side pulse modulation reference signal from the sampling frequency from the frequency of the local signal and the frequency of the pulse modulation reference signal. The radar apparatus according to claim 2, wherein the radar apparatus matches the value. The adjusting unit detects an error included in the reception side pulse modulation reference signal based on the pulse modulation reference signal and the local signal;
The frequency detector corrects the phases of the I signal and the Q signal based on an error included in the reception-side pulse modulation reference signal detected by the adjusting unit, and corrects the phase of the I signal and the Q signal. Detecting the Doppler frequency from
The radar apparatus according to claim 1 or 2 . A radar signal receiving method performed by a radar apparatus that holds information about a pulse repetition period of a radar signal,
Is pulse-modulated by the pulse modulation reference signal, receiving step local signal local oscillator of a predetermined frequency transmitted at the same timing as the pulse repetition period is outputted is reflected signals to target, receiving the radar signal When,
An amplification step for amplifying the radar signal;
A-D conversion step of sampling the amplified radar signal at a predetermined sampling frequency;
An oscillation step for outputting a reception-side pulse modulation reference signal having a frequency that is a difference between a value obtained by adding the frequency of the local signal and the frequency of the pulse modulation reference signal equal to or less than a threshold;
An adjustment step of adjusting the phase of the reception side pulse modulation reference signal by adjusting the phase reference of the reception side pulse modulation reference signal at the start time of the pulse repetition period ;
Based on the reception side pulse modulation reference signal adjusted in the adjustment step and a signal obtained by shifting the phase of the reception side pulse modulation reference signal by 90 degrees, phase detection of the radar signal sampled in the AD conversion step is performed. Performing a phase detection step of outputting an I signal and a Q signal;
A frequency detection step of detecting a Doppler frequency from the I signal and the Q signal;
A radar signal receiving method comprising:   A radar signal receiving method performed by a radar apparatus that holds information about a pulse repetition period of a radar signal,
  A receiving step for receiving a radar signal, wherein the local signal output by a local oscillator of a predetermined frequency, which is pulse-modulated with a pulse modulation reference signal and transmitted at the same timing as the pulse repetition period, is a signal reflected by a target; and ,
  An amplification step for amplifying the radar signal;
  A-D conversion step of sampling the amplified radar signal at a predetermined sampling frequency;
  An oscillation step of outputting a reception-side pulse modulation reference signal having a frequency that is a difference between a value obtained by subtracting the frequency of the local signal and the frequency of the pulse modulation reference signal from the sampling frequency, which is equal to or less than a threshold;
  An adjustment step of adjusting the phase of the reception side pulse modulation reference signal by adjusting the phase reference of the reception side pulse modulation reference signal at the start time of the pulse repetition period;
  Based on the reception side pulse modulation reference signal adjusted in the adjustment step and a signal obtained by shifting the phase of the reception side pulse modulation reference signal by 90 degrees, phase detection of the radar signal sampled in the AD conversion step is performed. Performing a phase detection step of outputting an I signal and a Q signal;
  A frequency detection step of detecting a Doppler frequency from the I signal and the Q signal;
  A radar signal receiving method comprising: In the adjusting step, the phase of the reception-side pulse modulation reference signal is adjusted so that the frequency of the reception-side pulse modulation reference signal matches a value obtained by adding the frequency of the local signal and the frequency of the pulse modulation reference signal. The radar signal receiving method according to claim 6 .   In the adjusting step, the phase of the reception side pulse modulation reference signal is adjusted, and the frequency of the reception side pulse modulation reference signal is subtracted from the sampling frequency and the frequency of the local signal and the frequency of the pulse modulation reference signal. The radar signal receiving method according to claim 7, wherein the radar signal is matched with a value. In the adjusting step, an error included in the reception side pulse modulation reference signal is detected based on the pulse modulation reference signal and the local signal,
In the frequency detection step, based on an error included in the reception-side pulse modulation reference signal detected in the adjustment step, the phase of the I signal and the Q signal is corrected, and the phase-corrected I signal and the Q signal Detecting the Doppler frequency from
The radar signal receiving method according to claim 6 or 7 .

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