JP4429126B2 - Radar equipment - Google Patents

Description

  The present invention relates to a reduction in high-frequency components and an improvement in measurement accuracy in a phase monopulse radar device.

  As a method for determining the azimuth of the target, a phase monopulse method is known in which the azimuth of the target is calculated from the phase difference between reflected waves received by two antennas. In a radar apparatus using a plurality of receiving antennas such as a phase monopulse method, expensive high-frequency components such as a receiving amplifier and a mixer are required for each receiving antenna, and therefore, the number of high-frequency components is required to be reduced.

  On the other hand, in the phase monopulse system, since the phase comparison of the received waves of two antennas is performed, it is required to process them simultaneously and in parallel.

  Accordingly, an object of the present invention is to reduce the number of high-frequency components of a phase monopulse radar device and to improve measurement accuracy.

According to the present invention, the first switch that alternately selects reception signals received by two of the plurality of antennas in each of the plurality of periods, and the reception signal selected by the first switch A mixer that mixes a part of the transmission signal to generate a beat signal, and a second switch that distributes the beat signal generated from the reception signals of the two antennas to the two processing systems. beat signal generated from the received signal, in equal distribution is the radar device to both of the processing system over a plurality of periods, each period of the plurality of periods, based on the beat signals distributed into two processing systems Computation means for computing the azimuth of the target, the computation means calculates the average value of the azimuth of the target calculated for each period of the plurality of periods Radar apparatus is provided, characterized in that the true azimuth of the definitive target.

  FIG. 1 is a block diagram showing a configuration of an in-vehicle FM-CW radar apparatus according to an embodiment of the present invention. In FIG. 1, a transmission signal which is output from a voltage controlled oscillator (VCO) 10 and is FM-modulated with a triangular wave is amplified by a transmission amplifier 14, passes through a circulator 16, and is selected by a switch 22 among antennas AT 0, AT 1 and AT 2. Sent from things. Similarly, for reception, the antenna selected from the three antennas AT0, AT1, AT2 by the switch 22 is used.

  The reception signal received by the selected antenna is amplified by the reception amplifier 26 via the circulator 16 and mixed with a part of the transmission wave in the mixer 28 to generate a beat signal. The beat signal generated in the mixer 28 is distributed to one of the two upper and lower systems in the figure by the switch 30, converted into a digital signal by the A / D converter 32, fast Fourier transformed (34), and input to the CPU 36. Is done. The mixer 31 is provided for canceling the frequency superimposed on the beat signal by mixing it with the same frequency because the transmission / reception is switched by the signal SWR.

  FIG. 2 shows a waveform of a triangular wave input to the voltage controlled oscillator 10 of FIG. 1, and columns (A) to (C) in FIG. 3 respectively show control signals SWT, SWR, The waveforms of SW0, SW1, and SW2 are shown. The (D) column in FIG. 3 shows the waveform of the control signal CH of the switch 30 with the same time scale and the same timing as the (A) to (C) columns. Note that the time scale on the horizontal axis in FIG. 2 is significantly compressed as compared with FIG.

  In the first period of the triangular wave shown in FIG. 2, that is, in section A, transmission by AT0 → reception by AT0 → transmission → reception by AT1 is repeated as can be seen from FIG. As can be seen from FIG. 3D, the beat signal based on the AT0 received signal is distributed to the upper system in the figure by the switch 30 in FIG. 1, and the beat signal based on the AT1 received signal is distributed to the lower system in the figure. And processed in parallel. That is, in the section A, beat signal data in the up and down sections of the triangular wave generated from the reception signals of the receiving antennas AT0 and AT1 are collected. The peak frequency appearing in these Fourier transform results is used for the calculation of the distance to the target and the relative speed, and the peak phase is used for the calculation of the phase monopulse by the antennas AT0 and AT1.

  In the next period of the triangular wave shown in FIG. 2, that is, the section B, as can be seen from FIG. 3B, transmission by AT0 → reception by AT1 → transmission by AT0 → reception by AT2 is repeated. As can be seen from FIG. 3D, the beat signal based on the AT1 received signal is distributed to the upper system in the figure by the switch 30 in FIG. 1, and the beat signal based on the AT2 received signal is distributed to the lower system in the figure. And processed in parallel. That is, in the section B, beat signal data in the up and down sections of the triangular wave generated from the reception signals of the receiving antennas AT1 and AT2 are collected. The peak frequency appearing in these Fourier transform results is used for the calculation of the distance to the target and the relative velocity, and the peak phase is used for the calculation of the phase monopulse by the antennas AT1 and AT2.

  In the further next period of the triangular wave shown in FIG. 2, that is, in section C, transmission by AT0 → reception by AT2 → transmission by AT0 → reception by AT0 is repeated, as can be seen from FIG. As can be seen from FIG. 3D, the beat signal based on the AT2 received signal is distributed to the upper system in the figure by the switch 30 in FIG. 1, and the beat signal based on the AT0 received signal is distributed to the lower system in the figure. And processed in parallel. That is, in section C, beat signal data in the up and down sections of the triangular wave generated from the reception signals of the receiving antennas AT2 and AT0 is collected. The frequency of the peak appearing in these Fourier transform results is used for the calculation of the distance to the target and the relative velocity, and the phase of the peak is used for the calculation of the phase monopulse by the antennas AT2 and AT0.

  As described above, the beat signal from the antenna AT0 is processed in the upper processing system in the section A, and is processed in the lower processing system in the section C. The beat signal from the antenna AT1 is processed in the lower processing system in the section A and in the upper processing system in the section B. The beat signal from the antenna AT2 is processed in the lower processing system in the section B and in the upper processing system in the section C. In other words, since the switching sequence is designed so that the beat signal from each antenna is equally distributed to both processing systems, as described below, errors due to variations in the parts used in each processing system are absorbed. be able to.

で計算される。ただし、ｄ_ijはアンテナＡＴ_iとＡＴ_jの間隔、φ_iはアンテナＡＴ_iについてのフーリエ変換結果に出現する反射波のピークにおける複素数値の偏角である。 Target orientations θ _{up, A} , θ _{up, B} , θ _{up, C} calculated from the results in the rising section of the triangular wave in sections A, B _{, C} are:

Calculated by Here, d _ij is the distance between the antennas AT _i and AT _j , and φ _i is the complex-valued declination angle at the peak of the reflected wave that appears in the Fourier transform result for the antenna AT _i .

Similarly, θ _{down, A} , θ _{down, B} , θ _{down, C} are calculated for the descending sections of the triangular wave in the sections A, B, and C, and the average value thereof is set as the target direction θ.

となり、アンテナと処理系のすべての組み合わせが網羅されているので、回路誤差による位相検出精度への影響を削減することができる。 Here, if the circuit errors in the two processing systems are e1 and e2, Equation (1) is

Thus, since all combinations of the antenna and the processing system are covered, the influence on the phase detection accuracy due to the circuit error can be reduced.

It is a figure which shows an example of a structure of the vehicle-mounted FM-CW radar apparatus which concerns on one Embodiment of this invention. It is a wave form diagram which shows the modulation wave by a triangular wave. It is a wave form diagram which shows the waveform of each control signal of FIG.

Claims (1)

In each successive plurality of time periods, a first switch for selecting the received signal received by the two antennas among the more than two antennas alternately,
A mixer that generates a beat signal by mixing a part of the transmission signal with the reception signal selected by the first switch;
A second switch that distributes the beat signals generated from the reception signals of the two antennas to the two processing systems,
Beat signal generated from the received signal of each antenna in the radar apparatus is distributed by the number of times that is equal to both the processing system over a plurality of periods in which the successive
Computation means for obtaining the azimuth of the target for each period based on the phase difference of the Fourier transform result of the beat signal distributed to the two processing systems,
The radar device according to claim 1, wherein the arithmetic means sets an average value of the azimuths of the targets calculated for each period as a true azimuth of the target in the plurality of periods.

Images