JP6130195B2 - Radar system - Google Patents

Description

  The present invention provides a radar system in which a radar transmitter and a radar receiver are separated from each other for the purpose of measuring the distance and speed of a target with high accuracy, and performing high-precision calibration of an array antenna on a transmission / reception side. For the purpose, it relates to technology to apply.

  The pulse radar system is applied for the purpose of measuring the distance and speed of a target. The radar transmitter transmits the generated radar pulse signal to the target. At the target, the irradiated radar pulse signal is reflected. The radar receiver receives the reflected radar pulse signal. The distance of the target is measured based on the round trip delay time of the radar pulse signal. The speed of the target in the radar direction is measured based on the Doppler frequency of the radar pulse signal.

A method for measuring the distance and speed of the target will be described. Radar pulse signal P _r radar pulse signal P _t and radar receiver radar transmitting apparatus transmits the received is expressed by the following equation.
P _t = A _t cos (ωt + θ _t ), P _r = A _r cos {ω (t−τ) + θ _r }.

Based on the round trip delay time τ of the radar pulse signal, the distance x of the target is obtained by the following equation. By measuring the phase difference Δφ = θ _r −θ _t over a predetermined time, the Doppler frequency f _d of the radar pulse signal is obtained. Based on the Doppler frequency f _d of the radar pulse signal, the speed v of the radar direction target object is obtained by the following equation.
x = cτ / 2 (c is the speed of light), v = (f _d / 2f) c (f is the transmission frequency).

  By the way, in the radar system in which the radar transmitter and the radar receiver are integrated, the radar transmission direction and the radar reception direction coincide with each other, so that the radar pulse signal is reflected in a direction different from the direction in which the radar pulse signal is emitted. The target is difficult to catch.

  On the other hand, in a radar system in which the radar transmitter and the radar receiver are separated from each other, the radar transmission direction and the radar reception direction do not match, so the radar pulse signal is reflected in a direction different from the direction in which the radar pulse signal is emitted. The target is easy to catch. For example, Patent Document 1 is an example of a document that applies a radar system in which the radar transmitter and the radar receiver are separated for the purpose of measuring the distance and speed of a target.

  Furthermore, in a radar system in which the radar transmitter and the radar receiver are separated from each other, it is possible to calibrate the transmitting / receiving array antenna by placing the transmitting / receiving array antenna facing each other. For example, Japanese Patent Application Laid-Open No. H10-260260 discloses a document that applies a radar system in a place where the radar transmitter and the radar receiver are separated for the purpose of calibrating the array antenna on the transmission / reception side.

  Here, in a radar system to which a parabolic antenna is applied, one antenna has a sharp beam directivity. Therefore, for radar measurement in all directions, it is necessary to scan the antenna in all directions. On the other hand, in a radar system using an array antenna, each of the plurality of antennas has a relatively wide beam directivity, and the beam forming process is performed on each measured amplitude / phase information to virtually direct the beam in an arbitrary direction. It is possible to scan. Therefore, it is not necessary to scan the antenna in all directions for radar measurement in all directions. Thus, a radar system using an array antenna can scan a beam at a higher speed than a radar system using a parabolic antenna.

  In radar systems that use array antennas, the variations in amplitude and phase information measured by multiple antennas reflect the variations in beam directivity that each of the multiple antennas has, and are corrected by prior calibration of the array antenna. is necessary. In advance array antenna calibration, the transmitting and receiving array antennas are placed facing each other, and the direct wave from the other antenna is measured in one array antenna, so that amplitude and phase information can be obtained in one array antenna. To compensate for variations.

JP 2011-191099 A JP 2010-071889 A

  By the way, in a radar system in which a radar transmitter and a radar receiver are integrated, it is easy to measure the difference in transmission / reception timing. If the same reference frequency is applied on the transmission / reception side, the phase of the transmission signal is used as a reference. It is easy to measure the phase of the received signal.

  On the other hand, in a radar system in which the radar transmitter and the radar receiver are separated from each other, the radar receiver needs to acquire the transmission timing for delay measurement from the radar transmitter, and set the reference frequency for phase measurement. It is necessary to match with the radar transmitter.

  As a method of synchronizing the oscillation frequency between the radar transmitter and the radar receiver, there is a method using a GPS (Global Positioning System) signal (see, for example, Patent Document 1). Therefore, the radar receiver can match the reference frequency with the radar transmitter by using the GPS signal.

  And a radar receiver can acquire from a radar transmitter if it is regular transmission timing by using a GPS signal. However, even if the radar receiver uses a GPS signal, it cannot be acquired from the radar transmitter at random transmission timing. Here, the radar transmission device randomizes the transmission timing when changing the pulse repetition frequency in order to variously change the upper limit of the distance that can be measured, or synchronism from other radars. This is when the stagger function is applied to suppress interference.

  Since the radar receiver cannot acquire random transmission timing from the radar transmitter, the radar receiver cannot sample the radar pulse signal.

  Therefore, in order to solve the above-described problem, the present invention provides a radar system in which the radar transmitter and the radar receiver are located apart from each other, even if the radar transmitter makes the transmission timing random. Enable signal sampling.

  To achieve the above object, the radar receiver receives an encoded repetition signal from the radar transmitter, and oscillates between the radar transmitter and the radar receiver based on the correlation result of the encoded repetition signal and the reference signal. Synchronize the frequency and phase.

  The radar pulse signal and the encoded pulse signal are transmitted from the radar transmitter at the same timing. When measuring the distance and speed of a target, the radar pulse signal propagates as a reflected wave from the radar transmitter to the radar receiver via the target. The encoded pulse signal propagates as a direct wave from the radar transmitter to the radar receiver. That is, the radar pulse signal arrives at the radar receiver later than the encoded pulse signal.

  The radar receiver receives the encoded pulse signal from the radar transmitter, and detects the reception timing of the encoded pulse signal based on the correlation result between the encoded pulse signal and the reference signal. The radar receiver then outputs information on the reception timing of the encoded pulse signal as a sampling trigger for the radar pulse signal. Then, the radar receiver can start sampling of the radar pulse signal after outputting the sampling trigger of the radar pulse signal.

  Specifically, the present invention is a radar system in which a radar transmitter and a radar receiver perform wireless communication, and the radar transmitter includes a radar pulse signal generator that generates a radar pulse signal, and the radar pulse signal. An encoded pulse signal generation unit that generates an encoded pulse signal at the same timing as the timing at which the generation unit generates the radar pulse signal, and an encoded repetition signal generation unit that generates an encoded repetition signal having repetition periodicity The radar pulse signal generated by the radar pulse signal generation unit, the encoded pulse signal generated by the encoded pulse signal generation unit, and the encoded repetition signal generated by the encoded repetition signal generation unit. A frequency up-conversion unit for frequency up-conversion to a radio frequency, and the frequency up-conversion unit A radar pulse signal transmission unit that transmits the radar pulse signal that has been up-converted several times to a radar measurement target; and the encoded pulse signal and the encoded repetition signal that have been frequency-upconverted by the frequency up-conversion unit to a radio frequency. An encoded signal transmitter that transmits to the radar receiver, and the radar receiver transmits the radar pulse signal transmitted from the radar pulse signal transmitter to the radar measurement target. A radar pulse signal receiving unit that receives from the radar transmitting device, and a coded signal receiving unit that receives the coded pulse signal and the coded repetition signal transmitted from the coded signal transmitting unit to the radar receiving device. The radar pulse signal received by the radar pulse signal receiver, and the encoded signal receiver A frequency down-conversion unit for down-converting a coded pulse signal and the coded repetition signal from a radio frequency; the coded repetition signal obtained by the frequency down-conversion unit performing frequency down-conversion from a radio frequency; and the radar receiver. Based on the correlation result of the reference signal related to the encoded repetition signal to be stored, the oscillation frequency / phase for synchronizing the frequency and phase of the oscillator included in the frequency down-conversion unit with the frequency and phase of the oscillator included in the frequency up-conversion unit A synchronization unit, a radar pulse signal sampling unit that performs sampling on the radar pulse signal that has been converted from a radio frequency to a frequency down by the frequency down conversion unit, and the code that has been converted from a radio frequency to a frequency down by the frequency down conversion unit Pulse signal and the coded pulse stored in the radar receiver Based on the correlation result of the reference signal related to the signal, the timing at which the radar receiving apparatus receives the encoded pulse signal is detected, and information about the timing at which the radar receiving apparatus receives the encoded pulse signal is used as the radar. A radar system comprising: a sampling trigger generation unit that outputs a pulse signal sampling unit as a trigger for sampling the radar pulse signal.

  According to this configuration, when measuring the distance and speed of a target in a radar system in which the transmitting and receiving sides are separated, even if the radar transmission device randomizes the transmission timing, the radar reception device transmits the radar pulse signal. Sampling becomes possible. Further, the reference frequency and transmission timing can be transmitted at low cost by wireless communication instead of a cable.

  To achieve the above object, the radar receiver receives an encoded repetition signal from the radar transmitter, and oscillates between the radar transmitter and the radar receiver based on the correlation result of the encoded repetition signal and the reference signal. Synchronize the frequency and phase.

  The radar pulse signal and the encoded pulse signal are transmitted from the radar transmitter at the same timing. The radar pulse signal propagates as a direct wave from the radar transmitter to the radar receiver when the array antenna on the transmission / reception side is calibrated. The encoded pulse signal propagates as a direct wave from the radar transmitter to the radar receiver. That is, the radar pulse signal reaches the encoded pulse signal and the radar receiver at the same time.

  The radar receiver receives the encoded pulse signal from the radar transmitter, and detects the reception timing of the encoded pulse signal based on the correlation result between the encoded pulse signal and the reference signal. The radar receiver then outputs information on the reception timing of the encoded pulse signal as a sampling trigger for the radar pulse signal. Furthermore, the radar receiver performs delay correction for the radar pulse signal by a predetermined amount. Then, the radar receiver can start sampling of the radar pulse signal that has been subjected to delay correction by a predetermined amount after outputting the sampling trigger of the radar pulse signal.

  Specifically, the present invention is a radar system in which a radar transmitter and a radar receiver perform wireless communication, and the radar transmitter includes a radar pulse signal generator that generates a radar pulse signal, and the radar pulse signal. An encoded pulse signal generation unit that generates an encoded pulse signal at the same timing as the timing at which the generation unit generates the radar pulse signal, and an encoded repetition signal generation unit that generates an encoded repetition signal having repetition periodicity The radar pulse signal generated by the radar pulse signal generation unit, the encoded pulse signal generated by the encoded pulse signal generation unit, and the encoded repetition signal generated by the encoded repetition signal generation unit. A frequency up-conversion unit for frequency up-conversion to a radio frequency, and the frequency up-conversion unit A radar pulse signal transmitter that transmits the radar pulse signal that has been converted several times upward to the radar receiver, and the encoded pulse signal and the encoded repetition signal that the frequency upward converter has converted to a radio frequency. An encoded signal transmission unit that transmits the radar pulse signal transmitted from the radar pulse signal transmission unit to the radar reception device. A radar pulse signal receiving unit that receives from the apparatus, and an encoded signal reception that receives the encoded pulse signal and the encoded repetition signal transmitted from the encoded signal transmitting unit to the radar receiving apparatus from the radar transmitting apparatus. , The radar pulse signal received by the radar pulse signal receiver, and the encoded signal receiver A frequency down-conversion unit for down-converting the encoded pulse signal and the encoded repetition signal from a radio frequency; the encoded repetition signal obtained by the frequency down-conversion unit performing frequency down conversion from a radio frequency; and the radar receiver. The frequency and phase of the oscillator included in the frequency down-conversion unit are synchronized with the frequency and phase of the oscillator included in the frequency up-conversion unit based on the correlation result of the reference signal related to the encoded repetition signal stored in Sampling is performed after delay correction is performed on the radar pulse signal that has been converted from a radio frequency by the phase synchronization unit and the frequency down conversion unit by a predetermined delay correction amount in the radar receiver. The radar pulse signal sampling unit to perform and the frequency down-conversion unit from the radio frequency Based on a correlation result between the encoded pulse signal whose frequency is down-converted and a reference signal related to the encoded pulse signal stored in the radar receiver, the timing at which the radar receiver receives the encoded pulse signal is detected. A sampling trigger generator that outputs information about the timing at which the radar receiver has received the encoded pulse signal as a trigger for the radar pulse signal sampling unit to sample the radar pulse signal; A radar system characterized by comprising:

  According to this configuration, in a radar system in which the transmission / reception side is remote, even when the radar transmission apparatus randomizes the transmission timing when the transmission / reception side array antenna is calibrated, the radar reception apparatus transmits the radar pulse signal. Sampling becomes possible. Further, the reference frequency and transmission timing can be transmitted at low cost by wireless communication instead of a cable.

  The radar receiver calculates the correlation result between the encoded pulse signal and the reference signal at the timing of supplying the operation clock signal, and samples the radar pulse signal.

  Here, the transmission timing, propagation delay time, and clock cycle are uncorrelated with each other. Therefore, the radar receiver cannot detect the true maximum value at the operation clock signal supply timing with respect to the correlation result between the encoded pulse signal and the reference signal, and the true maximum value at the operation clock non-supply timing. May produce a value. Specifically, the detected maximum value may occur at a time shifted by a maximum of 0.5 clock from the true maximum value.

  Then, the radar receiver may detect a time shifted by 0.5 clock at the maximum from the true time with respect to the reception timing of the encoded pulse signal. Then, the radar receiver may output a time that is shifted from the true time by 0.5 clock at the maximum with respect to the sampling trigger. Therefore, the radar receiver cannot start sampling after a certain time from the transmission timing in each pulse repetition period.

  Therefore, the radar receiving apparatus detects, as a true time, a time that is shifted by a maximum of 0.5 clock from the detected time with respect to the reception timing of the encoded pulse signal. Then, the radar receiver outputs, as a true time, a time that is shifted by a maximum of 0.5 clocks from the time before output for the sampling trigger. Therefore, the radar receiver can start sampling after a certain time from the transmission timing in each pulse repetition period.

  Specifically, the radar receiver further includes an operation clock signal supply unit that supplies an operation clock signal to the sampling trigger generation unit and the radar pulse signal sampling unit, and the sampling trigger The generation unit calculates a correlation result regarding the encoded pulse signal at a timing when the operation clock signal supply unit supplies the operation clock signal, and at a timing when the operation clock signal supply unit does not supply the operation clock signal. The correlation result related to the encoded pulse signal is interpolated, and the timing at which the correlation result related to the encoded pulse signal that has been interpolated takes the maximum value is detected as the timing at which the radar receiver receives the encoded pulse signal. The encoded pulse signal not interpolated The difference between the timing at which the correlation result takes the maximum value and the timing at which the correlation result for the encoded pulse signal that has been interpolated takes the maximum value is output as a delay correction amount within one clock, and the radar pulse signal sampling unit Is obtained by performing delay correction by the amount of delay correction in the one clock output by the sampling trigger generation unit, with respect to the radar pulse signal that the frequency down conversion unit performs frequency down conversion from a radio frequency. The radar system is characterized in that sampling is performed at a timing when the operation clock signal supply unit supplies the operation clock signal.

  Specifically, the radar receiver further includes an operation clock signal supply unit that supplies an operation clock signal to the sampling trigger generation unit and the radar pulse signal sampling unit, and the sampling trigger The generation unit calculates a correlation result regarding the encoded pulse signal at a timing when the operation clock signal supply unit supplies the operation clock signal, and at a timing when the operation clock signal supply unit does not supply the operation clock signal. The correlation result related to the encoded pulse signal is interpolated, and the timing at which the correlation result related to the encoded pulse signal that has been interpolated takes the maximum value is detected as the timing at which the radar receiver receives the encoded pulse signal. The encoded pulse signal not interpolated The difference between the timing at which the correlation result takes the maximum value and the timing at which the correlation result for the encoded pulse signal that has been interpolated takes the maximum value is output as a delay correction amount within one clock, and the radar pulse signal sampling unit The frequency down-conversion unit performs delay correction on the radar pulse signal converted from a radio frequency down-frequency by a predetermined delay correction amount in the radar receiver, and the sampling trigger generation unit The radar system is characterized in that sampling is performed at a timing when the operation clock signal supply unit supplies the operation clock signal after performing delay correction by an amount corresponding to the delay correction amount in the output one clock.

  According to this configuration, the radar receiver can detect the reception timing of the encoded pulse signal, output the sampling trigger, and correct the deviation of the sampling timing with high accuracy. Therefore, the radar receiver can measure the distance and speed of the target or calibrate the array antenna on the transmission / reception side with high accuracy.

  The radar transmission device may further include a transmission / reception parameter signal generation unit that generates a parameter signal required for transmission / reception at the same timing as the radar pulse signal generation unit generates the radar pulse signal. The frequency up-conversion unit frequency up-converts the parameter signal necessary for transmission / reception generated by the transmission / reception parameter signal generation unit into a radio frequency, and the encoded signal transmission unit includes the frequency up-conversion unit. The parameter signal required for the transmission / reception frequency-converted to a radio frequency is transmitted to the radar receiver, and the encoded signal receiver is transmitted to the radar receiver by the encoded signal transmitter. A parameter signal necessary for transmission / reception is received from the radar transmitter, and the frequency down-conversion unit receives the encoded signal. The parameter signal necessary for transmission / reception received by the unit is down-converted from a radio frequency, and the radar receiver demodulates the parameter signal necessary for transmission / reception converted from the radio frequency by the frequency down-conversion unit. The radar system further includes a transmission / reception parameter signal detection unit for detecting the transmission / reception parameter signal.

  According to this configuration, the radar receiver can acquire transmission waveform information, scanning direction information, and the like from the radar transmitter as parameters necessary for transmission and reception for each pulse repetition period. Therefore, the radar receiver can measure the distance and speed of the target or calibrate the array antenna on the transmission / reception side with high accuracy.

  The present invention enables a radar receiving apparatus to sample a radar pulse signal even if the radar transmitting apparatus randomizes the transmission timing in a radar system in which the radar transmitting apparatus and the radar receiving apparatus are separated from each other.

It is a figure which shows the structure of the radar transmitter of Embodiment 1. FIG. It is a figure which shows the structure of the radar receiver of Embodiment 1. FIG. It is a time chart which shows the transmission signal of this invention. It is a figure which shows the structure of the sampling trigger production | generation part of this invention. It is a figure which shows the process of the sampling trigger production | generation part of this invention. FIG. 3 is a diagram illustrating a configuration of a radar pulse signal sampling unit according to the first embodiment. It is a figure which shows the structure of the radar transmitter of Embodiment 2. It is a figure which shows the structure of the radar receiver of Embodiment 2. It is a figure which shows the structure of the radar pulse signal sampling part of Embodiment 2. FIG.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In the present specification and drawings, the same reference numerals denote the same components.

(Embodiment 1)
In the first embodiment, a radar system in which a radar transmitter and a radar receiver are separated is applied for the purpose of measuring the distance and speed of a target.

  First, the configuration of the radar system will be described. In the radar system, the radar transmitter 1 and the radar receiver 2 perform wireless communication. The configuration of the radar transmitter 1 is shown in FIG. The configuration of the radar receiver 2 is shown in FIG. A time chart showing a transmission signal is shown in FIG.

  The radar transmitter 1 is separate from the radar receiver 2, and includes a radar pulse signal generator 11, an encoded pulse signal generator 12, a transmission / reception parameter signal generator 13, an encoded repetition signal generator 14, and an upward frequency conversion. Section 15, transmission-side oscillator 16, radar pulse signal transmission section 17, and encoded signal transmission section 18.

  The radar pulse signal generation unit 11 generates a radar pulse signal. The radar pulse signal is, for example, an unmodulated short pulse signal and a frequency modulated pulse signal.

  The encoded pulse signal generation unit 12 generates an encoded pulse signal at the same timing as the radar pulse signal generation unit 11 generates the radar pulse signal. The encoded pulse signal is, for example, a pseudo random (PN) code signal.

  The transmission / reception parameter signal generation unit 13 generates a parameter signal necessary for transmission / reception at the same timing as the radar pulse signal generation unit 11 generates the radar pulse signal. Parameter signals necessary for transmission / reception are, for example, transmission waveform information and scanning direction information.

  For example, when the radar transmission device 1 changes the frequency modulation pulse signal for each pulse repetition period, the radar reception device 2 changes the reference signal at the time of pulse compression, so transmission corresponding to the frequency modulation pulse signal is performed. Number information is transmitted as transmission waveform information.

  When the radar transmitter 1 and the radar receiver 2 change the same scanning direction for each pulse repetition period, scanning direction information corresponding to the scanning direction is transmitted.

  The encoded repetition signal generation unit 14 generates an encoded repetition signal having repetition periodicity. The encoded repetition signal is, for example, a pseudo random (PN) code signal.

  Please refer to FIG. The transmission trigger is generated by the encoded pulse signal generation unit 12. The radar pulse signal, the encoded pulse signal, and the transmission / reception parameter signal are generated in synchronization with the transmission trigger. The coded repetition signal is generated independently of the transmission trigger.

  When the generation timing of the transmission trigger is random, the generation timing of the radar pulse signal is also random. Therefore, the pulse repetition frequency can be changed, and the upper limit of the distance that can be measured can be changed variously. Alternatively, a stagger function can be applied and synchronous interference from other radars can be suppressed.

  Here, the encoded pulse signal, the transmission / reception parameter signal, and the encoded repetition signal are collectively transmitted from the encoded signal transmitter 18 of the radar transmitter 1 to the encoded signal receiver 22 of the radar receiver 2. The Therefore, it is desirable that the encoded pulse signal, the transmission / reception parameter signal, and the encoded repetition signal are codes having high orthogonality.

  The frequency up-conversion unit 15 includes a radar pulse signal generated by the radar pulse signal generation unit 11, an encoded pulse signal generated by the encoded pulse signal generation unit 12, and a parameter signal necessary for transmission / reception generated by the transmission / reception parameter signal generation unit 13. The encoded repetition signal generated by the encoded repetition signal generation unit 14 is frequency-upconverted to a radio frequency.

Of the input signals from the generators 11 to 14, the I component is IN_I and the Q component is IN_Q. Of the output signal from the frequency upward conversion unit 15, the I component is OUT_I and the Q component is OUT_Q. The transmission-side oscillator 16 outputs a sin value and a cos value for each clock according to the fixed frequency and phase settings. The input / output relational expression is as follows.
OUT_I = IN_I * cos-IN_Q * sin
OUT_Q = IN_I * sin + IN_Q * cos

  For the output signal, the image frequency component is suppressed using a bandpass filter. Further, it may be up-converted from the baseband frequency directly to the radio frequency, or may be up-converted from the baseband frequency to the radio frequency via the intermediate frequency.

  The radar pulse signal transmission unit 17 transmits the radar pulse signal frequency-upconverted by the frequency up-conversion unit 15 to the radio frequency to the radar measurement target. The encoded signal transmission unit 18 transmits the encoded pulse signal frequency-converted by the frequency upward conversion unit 15 to the radio frequency, the parameter signal necessary for transmission / reception, and the encoded repetition signal to the radar receiver 2.

  The radar receiver 2 is separate from the radar transmitter 1 and includes a radar pulse signal receiver 21, an encoded signal receiver 22, a frequency down converter 23, a receiving oscillator 24, an oscillation frequency / phase synchronizer 25, A radar pulse signal sampling unit 26, a sampling trigger generation unit 27, a transmission / reception parameter signal detection unit 28, and an operation clock signal supply unit 29 are included.

  The radar pulse signal receiving unit 21 receives the radar pulse signal transmitted from the radar pulse signal transmitting unit 17 to the radar measurement target from the radar measurement target. The encoded signal receiving unit 22 receives the encoded pulse signal transmitted from the encoded signal transmitting unit 18 to the radar receiver 2, the parameter signal necessary for transmission / reception, and the encoded repetition signal from the radar transmitter 1.

  The frequency down conversion unit 23 wirelessly transmits the radar pulse signal received by the radar pulse signal reception unit 21, the encoded pulse signal received by the encoded signal reception unit 22, the parameter signal necessary for transmission / reception, and the encoded repetition signal. Frequency down conversion from frequency.

Of the input signals from the receiving units 21 and 22, the I component is IN_I. Of the output signal from the frequency down converter 23, the I component is OUT_I and the Q component is OUT_Q. The receiving-side oscillator 24 outputs a sin value and a cos value for each clock according to the frequency and phase settings output by the oscillation frequency / phase synchronization unit 25. The reception-side oscillator 24 is synchronized in frequency and phase with the transmission-side oscillator 16. The input / output relational expression is as follows.
OUT_I = IN_I * cos
OUT_Q = IN_I * sin

  For the output signal, a high-frequency component is suppressed using a low-pass filter. Further, it may be down-converted directly from the radio frequency to the baseband frequency, or down-converted from the radio frequency to the baseband frequency via the intermediate frequency.

  The oscillation frequency / phase synchronization unit 25 determines the frequency based on the correlation result between the coded repetition signal that the frequency down-conversion unit 23 performs frequency down-conversion from the radio frequency and the reference signal related to the coding repetition signal stored in the radar receiver 2. The frequency and phase of the reception-side oscillator 24 used by the lower conversion unit 23 are synchronized with the frequency and phase of the transmission-side oscillator 16 used by the frequency upper conversion unit 15. The oscillation frequency / phase synchronization unit 25 can use a GPS synchronization method.

  The oscillation frequency / phase synchronization unit 25 calculates the correlation between the encoded repetition signal and the reference signal, in the code tracking process for correcting the deviation between the encoded repetition signal and the reference signal, and the correlation result between the encoded repetition signal and the reference signal, Carrier tracking processing for correcting the frequency and phase of the reception-side oscillator 24 so that the Q component becomes 0 is simultaneously performed.

  The radar pulse signal sampling unit 26 performs sampling on the radar pulse signal that the frequency down conversion unit 23 converts from the radio frequency to the frequency down.

  The sampling trigger generation unit 27 is based on the correlation result between the encoded pulse signal that the frequency down conversion unit 23 converts from the radio frequency down to the frequency and the reference signal related to the encoded pulse signal stored in the radar receiver 2. 2 detects the timing at which the encoded pulse signal is received. Then, information on the timing at which the radar receiver 2 receives the encoded pulse signal is output as a trigger for the radar pulse signal sampling unit 26 to sample the radar pulse signal. Furthermore, the transmission / reception parameter signal detector 28 is notified of the timing at which the radar receiver 2 receives the encoded pulse signal.

  Thereby, the radar pulse signal sampling unit 26 can start sampling of the radar pulse signal after outputting the sampling trigger of the radar pulse signal.

  The transmission / reception parameter signal detection unit 28 demodulates and detects a parameter signal necessary for transmission / reception that the frequency down conversion unit 23 performs frequency down conversion from the radio frequency.

  Thereby, the radar receiver 2 can measure the distance and speed of the target with high accuracy using the transmission waveform information and the scanning direction information for each pulse repetition period.

  In the measurement of the distance and speed of the target, the calculation processing shown in the background art may be performed by the radar receiver 2 or the radar transmitter 1, or the radar transmitter 1 and the radar receiver 2. May be performed by a radar control device (not shown) that controls the above.

  The operation clock signal supply unit 29 supplies an operation clock signal to the sampling trigger generation unit 27 and the radar pulse signal sampling unit 26.

  Next, details of the sampling trigger and sampling will be described. The configuration of the sampling trigger generator 27 is shown in FIG. The processing of the sampling trigger generation unit 27 is shown in FIG. The configuration of the radar pulse signal sampling unit 26 is shown in FIG.

  The sampling trigger generation unit 27 includes a sliding correlation unit 271 and a maximum value detection unit 272. The radar pulse signal sampling unit 26 includes a sampling unit 261, an FIR (Finite Impulse Response) filter coefficient memory unit 262, and an FIR filter unit 263.

  The sliding correlation unit 271 calculates a correlation result regarding the encoded pulse signal at the timing when the operation clock signal supply unit 29 supplies the operation clock signal. The maximum value detection unit 272 detects the timing at which the correlation result regarding the encoded pulse signal takes the maximum value as the timing at which the radar receiver 2 receives the encoded pulse signal.

  In FIG. 5, the chip length of the encoded pulse signal is 2 clocks, the correlation waveform related to the encoded pulse signal is an ideal triangular waveform, and the supply timing of the operation clock signal is T, T ( -2), T (-1), T (0), T (1), T (2),.

  On the left side of FIG. 5, the correlation result at time T (−1) is ½, the correlation result at time T (0) is 1, and the correlation result at time T (1) is ½. It is. Since the timing at which the correlation result takes the maximum value is T (0), the detected reception timing is T (0), and the detected reception timing T (0) is equal to the true reception timing T (P). .

  On the left side of FIG. 5, since the transmission timing, the propagation delay time, and the clock cycle are in an appropriate relationship, the true reception timing T (P) can be detected. Therefore, it is not necessary to correct the reception timing, sampling trigger, and sampling timing.

  On the right side of FIG. 5, the correlation result at time T (-1) is E, the correlation result at time T (0) is P (<1), and the correlation result at time T (1) is L. It is. Since the timing at which the correlation result takes the maximum value is T (0), the detected reception timing is T (0). However, the detected reception timing T (0) is different from the true reception timing T (P). .

  On the right side of FIG. 5, since the transmission timing, propagation delay time, and clock cycle are not in an appropriate relationship, the true reception timing T (P) cannot be detected. Therefore, it is necessary to determine whether it is necessary to correct the reception timing, the sampling trigger, and the sampling timing in consideration of the necessary measurement accuracy of the radar measurement.

  In the case of the left side of FIG. 5 and the right side of FIG. 5, when it is not necessary to correct the reception timing, sampling trigger, and sampling timing, the following processing is performed.

  The maximum value detection unit 272 detects the timing T (0) at which the calculated correlation result regarding the encoded pulse signal takes the maximum value as the timing at which the radar receiver 2 receives the encoded pulse signal. Information about the timing at which the radar receiver 2 receives the encoded pulse signal is output as a trigger for the sampling unit 261 of the radar pulse signal sampling unit 26 to sample the radar pulse signal.

  The sampling unit 261 of the radar pulse signal sampling unit 26 performs sampling at the timing at which the operation clock signal supply unit 29 supplies the operation clock signal to the radar pulse signal that is converted from the radio frequency by the frequency down conversion unit 23. Do.

  When it is necessary to correct the reception timing, sampling trigger, and sampling timing on the right side of FIG. 5, the following processing is performed.

  The maximum value detection unit 272 interpolates the correlation result regarding the encoded pulse signal at the timing when the operation clock signal supply unit 29 does not supply the operation clock signal. Then, the timing T (P) at which the correlation result regarding the encoded pulse signal that has been interpolated takes the maximum value is detected as the timing at which the radar receiver 2 receives the encoded pulse signal.

  On the right side of FIG. 5, T (P) = T (0) − (E−L) / (E + L) is calculated.

  The maximum value detector 272 outputs information about the timing at which the radar receiver 2 receives the encoded pulse signal as a trigger for the sampling unit 261 of the radar pulse signal sampling unit 26 to sample the radar pulse signal. To do. The difference between the timing T (0) at which the correlation result regarding the encoded pulse signal not interpolated takes the maximum value and the timing T (P) at which the correlation result regarding the encoded pulse signal interpolated takes the maximum value. Is output as a delay correction amount within one clock.

  On the right side of FIG. 5, the delay correction amount within one clock = (E−L) / (E + L) is calculated.

  The FIR filter unit 263 corresponds to the amount of delay correction within one clock output from the maximum value detection unit 272 of the sampling trigger generation unit 27 with respect to the radar pulse signal that the frequency down conversion unit 23 performs frequency down conversion from the radio frequency. Perform delay correction. The FIR filter coefficient memory unit 262 stores FIR filter coefficients related to various group delays, and reads FIR filter coefficients related to group delays according to the delay correction amount within one clock.

  The sampling unit 261 performs sampling at the timing when the operation clock signal supply unit 29 supplies the operation clock signal to the radar pulse signal that has been subjected to delay correction by the amount of delay correction within one clock by the FIR filter unit 263. Do.

(Embodiment 2)
In the second embodiment, a radar system in which the radar transmitter and the radar receiver are separated is applied for the purpose of calibrating the array antenna on the transmission / reception side.

  Below, the place where Embodiment 1, 2 differs is mainly demonstrated. Next, calibration of the array antenna on the receiving side will be described. However, the same applies to the calibration of the array antenna on the transmission side.

  The configuration of the radar transmitter 1 is shown in FIG. The configuration of the radar receiver 2 is shown in FIG. The configuration of the radar pulse signal sampling unit 26 is shown in FIG.

  The radar pulse signal transmission unit 17 transmits the radar pulse signal frequency-upconverted by the frequency upward conversion unit 15 to a radio frequency to the radar receiver 2. One radar pulse signal transmitter 17 is used for calibration of the array antenna on the receiving side.

  The radar pulse signal receiver 21 receives the radar pulse signal transmitted from the radar pulse signal transmitter 17 to the radar receiver 2 from the radar transmitter 1. In calibration of the array antenna on the receiving side, a plurality of radar pulse signal receiving units 21 are used.

  In the calibration of the receiving-side array antenna, the radar pulse signal and the encoded pulse signal are transmitted from the radar transmitter 1 at the same timing, and propagated as a direct wave from the radar transmitter 1 to the radar receiver 2, It reaches the radar receiver 2 at the same time.

  The radar pulse signal sampling unit 26 performs a delay correction on the radar pulse signal that has been converted from the radio frequency by the frequency down conversion unit 23 by a predetermined delay correction amount in the radar receiver 2. Sampling is performed. In calibration of the array antenna on the receiving side, the radar pulse signal sampling unit 26 performs sampling on each radar pulse signal received by each radar pulse signal receiving unit 21.

  Even after the radar pulse signal sampling unit 26 receives the sampling trigger output from the sampling trigger generation unit 27, the radar pulse signal output from the frequency down conversion unit 23 can be sampled from the rising stage. The delay correction amount is determined in advance in the radar receiver 2 so that it can be performed.

  Thereby, the radar pulse signal sampling unit 26 can start sampling of the radar pulse signal after outputting the sampling trigger of the radar pulse signal.

  The transmission / reception parameter signal detection unit 28 demodulates and detects a parameter signal necessary for transmission / reception that the frequency down conversion unit 23 performs frequency down conversion from the radio frequency.

  Thereby, the radar receiver 2 can calibrate the array antenna on the transmission / reception side with high accuracy by using the transmission waveform information and the scanning direction information for each pulse repetition period. For example, the radar receiver 2 can obtain a high time division property by using pulse compression processing, and can separate a direct wave and a multipath reflected wave.

  In the calibration of the array antenna on the transmission / reception side, the correction processing for variations in amplitude / phase information of the array antenna on the transmission / reception side may be performed by the radar receiver 2 or the radar transmitter 1. You may carry out by the radar control apparatus (not shown) which controls the transmission apparatus 1 and the radar receiver 2 in an integrated manner.

  In the case of the left side of FIG. 5 and the right side of FIG. 5, when it is not necessary to correct the reception timing, sampling trigger, and sampling timing, the following processing is performed.

  The FIR filter unit 263 performs delay correction on the radar pulse signal that is converted from the radio frequency by the frequency down conversion unit 23 by a predetermined delay correction amount in the radar receiver 2. The FIR filter coefficient memory unit 262 stores FIR filter coefficients related to various group delays, and reads FIR filter coefficients related to group delays according to predetermined delay correction amounts.

  The sampling unit 261 performs sampling at the timing when the operation clock signal supply unit 29 supplies the operation clock signal to the radar pulse signal that has been subjected to delay correction by a predetermined delay correction amount by the FIR filter unit 263. Do.

  When it is necessary to correct the reception timing, sampling trigger, and sampling timing on the right side of FIG. 5, the following processing is performed.

  The FIR filter unit 263 performs delay correction on the radar pulse signal converted by the frequency down conversion unit 23 from the radio frequency to the frequency down by a predetermined delay correction amount in the radar receiver 2 and detects the maximum value. Delay correction is performed by the amount of delay correction within one clock output from the unit 272. The FIR filter coefficient memory unit 262 stores FIR filter coefficients related to various group delays, and sets FIR filter coefficients related to group delays according to the addition of a predetermined delay correction amount and a delay correction amount within one clock. read out.

  In the sampling unit 261, the operation clock signal supply unit 29 operates the operation clock with respect to the radar pulse signal in which the FIR filter unit 263 performs delay correction by the addition of the predetermined delay correction amount and the delay correction amount within one clock. Sampling is performed at the timing of supplying a signal.

  Here, each radar pulse signal received by each radar pulse signal receiver 21 is the same direct wave except for a multipath reflected wave. In calibration of the receiving-side array antenna, variations in amplitude / phase information of the receiving-side array antenna are corrected. Therefore, in the calibration of the array antenna on the receiving side, it is sufficient that the radar pulse signals received by the radar pulse signal receiving units 21 can be simultaneously sampled, and only the amount of delay correction within one clock is sufficient. This delay correction need not be performed.

  The radar system of the present invention can be applied for the purpose of increasing the measurement accuracy of radar measurement when the radar transmitter and the radar receiver are located at a distance. For example, the present invention can be applied for the purpose of measuring the distance and speed of the target with high accuracy and the purpose of performing high-precision calibration of the array antenna on the transmission / reception side.

1: Radar transmitter 2: Radar receiver 11: Radar pulse signal generator 12: Encoded pulse signal generator 13: Transmission / reception parameter signal generator 14: Encoded repetition signal generator 15: Up-frequency converter 16: Transmission side Oscillator 17: Radar pulse signal transmitter 18: Encoded signal transmitter 21: Radar pulse signal receiver 22: Encoded signal receiver 23: Frequency down converter 24: Receiving-side oscillator 25: Oscillation frequency / phase synchronizer 26: Radar pulse signal sampling unit 27: Sampling trigger generation unit 28: Transmission / reception parameter signal detection unit 29: Operation clock signal supply unit 261: Sampling unit 262: FIR filter coefficient memory unit 263: FIR filter unit 271: Sliding correlation unit 272: Maximum value Detection unit

Claims (5)

A radar system in which a radar transmitter and a radar receiver perform wireless communication,
The radar transmitter is
A radar pulse signal generator for generating a radar pulse signal;
An encoded pulse signal generation unit that generates an encoded pulse signal at the same timing as the radar pulse signal generation unit generates the radar pulse signal;
An encoded repetition signal generator for generating an encoded repetition signal having repetition periodicity;
The radar pulse signal generated by the radar pulse signal generation unit, the encoded pulse signal generated by the encoded pulse signal generation unit, and the encoded repetition signal generated by the encoded repetition signal generation unit are wirelessly transmitted. A frequency up-conversion unit for frequency up-conversion to frequency;
A radar pulse signal transmission unit for transmitting the radar pulse signal frequency-converted by the frequency conversion unit to a radio frequency to a radar measurement target;
An encoded signal transmission unit that transmits the encoded pulse signal and the encoded repetition signal that have been frequency-upconverted to a radio frequency by the frequency upward conversion unit, to the radar receiver;
With
The radar receiver is
A radar pulse signal receiving unit that receives the radar pulse signal transmitted from the radar pulse signal transmission unit to the radar measurement target;
An encoded signal receiver that receives the encoded pulse signal and the encoded repetition signal transmitted from the encoded signal transmitter to the radar receiver from the radar transmitter;
A frequency down-conversion unit that down-converts the radar pulse signal received by the radar pulse signal reception unit, and the encoded pulse signal and the encoded repetition signal received by the encoded signal reception unit from a radio frequency. ,
An oscillator included in the frequency down-conversion unit based on a correlation result of the encoded repetitive signal that the frequency down-conversion unit performs frequency down-conversion from a radio frequency and a reference signal related to the encoded repetitive signal stored in the radar receiver. An oscillation frequency / phase synchronization unit that synchronizes the frequency and phase with the frequency and phase of the oscillator included in the frequency up-conversion unit,
A radar pulse signal sampling unit that performs sampling on the radar pulse signal that has been converted from a radio frequency by the frequency down conversion unit;
Based on a correlation result between the encoded pulse signal that has been frequency-converted by the frequency down-conversion unit from the radio frequency and a reference signal related to the encoded pulse signal that is stored in the radar receiver, the radar receiver has encoded the signal. The timing at which a pulse signal is received is detected, and information about the timing at which the radar receiver receives the encoded pulse signal is used as a trigger for the radar pulse signal sampling unit to sample the radar pulse signal. A sampling trigger generator to output;
A radar system comprising: The radar receiver is
An operation clock signal supply unit that supplies an operation clock signal to the sampling trigger generation unit and the radar pulse signal sampling unit;
Further comprising
The sampling trigger generator is
At the timing when the operation clock signal supply unit supplies the operation clock signal, a correlation result regarding the encoded pulse signal is calculated,
Interpolating a correlation result regarding the encoded pulse signal at a timing when the operation clock signal supply unit does not supply the operation clock signal,
The timing at which the correlation result regarding the encoded pulse signal that has been interpolated takes the maximum value is detected as the timing at which the radar receiver receives the encoded pulse signal,
Delay correction within one clock is the difference between the timing when the correlation result regarding the encoded pulse signal not interpolated takes the maximum value and the timing when the correlation result regarding the encoded pulse signal interpolated takes the maximum value. Output as quantity,
The radar pulse signal sampling unit is
After the frequency down-conversion unit performs delay correction on the radar pulse signal frequency-converted from the radio frequency by the amount of delay correction in the one clock output from the sampling trigger generation unit, the operation clock The radar system according to claim 1, wherein sampling is performed at a timing when the signal supply unit supplies the operation clock signal. A radar system in which a radar transmitter and a radar receiver perform wireless communication,
The radar transmitter is
A radar pulse signal generator for generating a radar pulse signal;
An encoded pulse signal generation unit that generates an encoded pulse signal at the same timing as the radar pulse signal generation unit generates the radar pulse signal;
An encoded repetition signal generator for generating an encoded repetition signal having repetition periodicity;
The radar pulse signal generated by the radar pulse signal generation unit, the encoded pulse signal generated by the encoded pulse signal generation unit, and the encoded repetition signal generated by the encoded repetition signal generation unit are wirelessly transmitted. A frequency up-conversion unit for frequency up-conversion to frequency;
A radar pulse signal transmission unit that transmits the radar pulse signal frequency-converted by the frequency conversion unit to a radio frequency to the radar receiver;
An encoded signal transmission unit that transmits the encoded pulse signal and the encoded repetition signal that have been frequency-upconverted to a radio frequency by the frequency upward conversion unit, to the radar receiver;
With
The radar receiver is
A radar pulse signal receiver that receives from the radar transmitter the radar pulse signal that the radar pulse signal transmitter has transmitted to the radar receiver;
An encoded signal receiver that receives the encoded pulse signal and the encoded repetition signal transmitted from the encoded signal transmitter to the radar receiver from the radar transmitter;
A frequency down-conversion unit that down-converts the radar pulse signal received by the radar pulse signal reception unit, and the encoded pulse signal and the encoded repetition signal received by the encoded signal reception unit from a radio frequency. ,
An oscillator included in the frequency down-conversion unit based on a correlation result of the encoded repetitive signal that the frequency down-conversion unit performs frequency down-conversion from a radio frequency and a reference signal related to the encoded repetitive signal stored in the radar receiver. An oscillation frequency / phase synchronization unit that synchronizes the frequency and phase with the frequency and phase of the oscillator included in the frequency up-conversion unit,
Radar pulse signal sampling in which the radar down signal is subjected to delay correction by a predetermined delay correction amount in the radar receiver for the radar pulse signal frequency down converted from a radio frequency by the frequency down conversion unit. And
Based on a correlation result between the encoded pulse signal that has been frequency-converted by the frequency down-conversion unit from the radio frequency and a reference signal related to the encoded pulse signal that is stored in the radar receiver, the radar receiver has encoded the signal. The timing at which a pulse signal is received is detected, and information about the timing at which the radar receiver receives the encoded pulse signal is used as a trigger for the radar pulse signal sampling unit to sample the radar pulse signal. A sampling trigger generator to output;
A radar system comprising: The radar receiver is
An operation clock signal supply unit that supplies an operation clock signal to the sampling trigger generation unit and the radar pulse signal sampling unit;
Further comprising
The sampling trigger generator is
At the timing when the operation clock signal supply unit supplies the operation clock signal, a correlation result regarding the encoded pulse signal is calculated,
Interpolating a correlation result regarding the encoded pulse signal at a timing when the operation clock signal supply unit does not supply the operation clock signal,
The timing at which the correlation result regarding the encoded pulse signal that has been interpolated takes the maximum value is detected as the timing at which the radar receiver receives the encoded pulse signal,
Delay correction within one clock is the difference between the timing when the correlation result regarding the encoded pulse signal not interpolated takes the maximum value and the timing when the correlation result regarding the encoded pulse signal interpolated takes the maximum value. Output as quantity,
The radar pulse signal sampling unit is
The radar down-converting unit performs delay correction on the radar pulse signal frequency-converted from a radio frequency by a predetermined delay correction amount in the radar receiver, and the sampling trigger generating unit outputs the delay correction. The radar according to claim 3, wherein sampling is performed at a timing when the operation clock signal supply unit supplies the operation clock signal after performing delay correction by an amount corresponding to the delay correction amount in the one clock. system. The radar transmitter is
A transmission / reception parameter signal generation unit that generates a parameter signal necessary for transmission / reception at the same timing as the radar pulse signal generation unit generates the radar pulse signal;
Further comprising
The frequency up-conversion unit converts the parameter signal necessary for transmission / reception generated by the transmission / reception parameter signal generation unit into a radio frequency,
The encoded signal transmission unit transmits the parameter signal necessary for transmission / reception, which the frequency up-conversion unit frequency up-converts to a radio frequency, to the radar receiver,
The encoded signal receiving unit receives the parameter signal necessary for the transmission / reception transmitted from the encoded signal transmitting unit to the radar receiving device from the radar transmitting device,
The frequency down-conversion unit converts the parameter signal necessary for the transmission / reception received by the encoded signal reception unit from a radio frequency down-frequency,
The radar receiver is
A transmission / reception parameter signal detection unit that demodulates and detects the parameter signal necessary for the transmission / reception that the frequency down conversion unit performs frequency down conversion from a radio frequency;
The radar system according to claim 1, further comprising:

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