JP2005214672A - Microwave pulse radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely detect the distance to a detection object with a microwave pulse radar system of a simple constitution by precisely detecting a rise of reflection wave. <P>SOLUTION: The pulse radar system comprises a transmission means including an oscillator 2 for making a microwave into pulse and transmitting transmission signal as pulse wave and a transmission antenna 7, a reception means for receiving reflection wave formed by reflection of transmitted wave at an object, by way of an antenna 8, a mixing means 11 for mixing the reception signal and transmission signal to produce a Doppler signal, a rise signal detecting means 3 for outputting detection signal when the rise of Doppler signal reaches a preset threshold, and a distance measuring detecting means (distance operator) 6 for calculating the distance to the object d=(t2-t1)×C/2 (where C is light velocity) from the rise time (reception time) t2 being output information of the signal detection means 3 and the transmission time t1 being output information from the oscillator 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a microwave pulse radar device.

Conventionally, microwaves are transmitted and received, and the distance is measured by the time difference between the transmission and reception. For example, the high frequency signal of 24.125 GHz from the transmission circuit is turned on / off and transmitted to the outside of the apparatus, the reflected wave from the object of the transmitted high frequency signal is received, and the high frequency of 24.125 GHz generated by the transmission circuit is received. There is known a pulse radar device that mixes with a signal, performs AM detection, differentiates the detected waveform with a differentiating circuit, detects the rising of the reflected wave from a positive differential output, and measures the distance to the object. (For example, refer to Patent Document 1).
JP 2002-365362 A

  However, in the method of differentiating the waveform obtained by AM detection as described above and detecting the rising of the reflected wave, there is a problem that an error occurs in the detection of the rising time.

  An object of the present invention is to solve the above-described problems, and to provide a microwave pulse radar device capable of accurately detecting the rising of a reflected wave with a simple configuration and accurately detecting the distance to a detection target. And

  In order to achieve the above object, the invention of claim 1 is directed to transmitting means for transmitting a transmission signal as a pulsed radio wave, and receiving to receive a reflected wave formed by reflecting the radio wave transmitted by the transmitting means on an object. Mixing means for mixing a reception signal from the reception means with the transmission signal to obtain a Doppler signal, and a rising signal detection means for outputting a detection signal when the rising edge of the Doppler signal reaches a preset threshold value; A microwave pulse radar apparatus comprising: a distance measurement detection unit that calculates a distance to the object based on an output of the rising signal detection unit and determines the presence or absence of the object.

  According to a second aspect of the present invention, in the microwave pulse radar device according to the first aspect, the rising signal detecting means includes means for detecting a rising edge of a signal obtained by taking an absolute value of the Doppler signal.

  According to a third aspect of the present invention, there is provided the microwave pulse radar apparatus according to the first aspect, wherein the mixing means includes two, the rising signal detecting means includes an absolute value of a Doppler signal by the first mixing means, and a second value. The rising edge of the sum signal of the signal obtained by shifting the transmission signal by 90 ° by the mixing means and the absolute value of the Doppler signal obtained by mixing the reception signal from the receiving means is detected.

  According to a fourth aspect of the present invention, there is provided the microwave pulse radar device according to the first aspect, wherein there are two mixing means, the rising signal detecting means is a square of the Doppler signal by the first mixing means, The rising edge of the sum signal of the signal obtained by phase-shifting the transmission signal by 90 ° and the square of the Doppler signal obtained by mixing the reception signal from the receiving device is detected.

  According to the invention of claim 1, since the rising of the Doppler signal obtained by mixing the received signal with the transmission signal reaches the preset threshold value, the rising of the reflected wave is detected so as to output the detection signal. Rising edge can be detected more directly than differential processing, and therefore accurate time difference information can be obtained by obtaining accurate time difference information.

  According to the second aspect of the present invention, since the rise of the signal obtained by performing the absolute value processing on the Doppler signal obtained by mixing the reception signal with the transmission signal is detected, the reflection depends on the reflection condition on the detection target. Uncertainty in the phase information of the waveform can be removed, and in addition to the above effects, the accuracy can be further improved.

  According to the invention of claim 3, the uncertainty of the phase information of the reflected waveform is added by adding two signal waveforms obtained by performing absolute value processing of the Doppler signal and absolute value processing of the 90 ° phase-shifted Doppler signal. It can be removed and produces the same effect as described above.

  According to the fourth aspect of the present invention, the uncertainty of the phase information of the reflected waveform is obtained by adding the two signal waveforms obtained by performing the square process of the Doppler signal and the square process of the Doppler signal subjected to the 90 ° phase shift process. It can be removed and produces the same effect as described above.

  Hereinafter, a microwave pulse radar device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block configuration of the pulse radar apparatus according to the first embodiment, and FIG. 2 shows a transmission wave a and a rising detection target wave c by this apparatus. The pulse radar device pulsates a microwave and transmits a transmission signal as a pulsed radio wave, including a transmitter 2 and a transmission antenna 7, and the radio wave transmitted by the transmission means is applied to an object (detection target). Receiving means for receiving the reflected wave formed by reflection via the receiving antenna 8, a mixing means 11 for obtaining a Doppler signal by mixing a reception signal from the receiving means with a transmission signal, and a Doppler signal D (FIG. 2) Rising signal detection means (waveform rising detector) 3 that outputs a detection signal when the rising edge of the signal reaches a preset threshold value, and distance measurement detection means (distance calculator) 6 that calculates the distance to the object. ing. The distance calculator 6 calculates the distance to the object based on the rising time (reception time) t2 that is output information of the rising signal detection means 3 and the transmission time t1 that is output information from the transmitter 2.

  In the apparatus configured as described above, the time t from transmission to reception of the transmission signal is obtained by t = t2−t1, as shown in FIG. 2, and the distance d is d = t × C / 2 (where C Is determined by the speed of light). Specifically, the counter starts counting the number of time reference pulses generated by the clock generator CL from the transmission time t1, and obtains t, and thus the distance d, from the number of pulses and the pulse interval when the counting ends at the reception time t2. It is done.

  As described above, the rising of the reflected wave is detected by outputting the detection signal when the rising of the Doppler signal obtained by mixing the reception signal with the transmission signal reaches a preset threshold value. Also, the rising edge can be detected directly, and therefore accurate time difference information can be obtained and accurate distance detection to the detection object can be performed. Note that the obtained distance d may include an error due to the uncertainty of the phase information of the reflected waveform generated depending on the reflection condition on the detection target, and further improve the accuracy of distance detection. It can be improved. This will be described with reference to FIG. The phase of the received waveform changes depending on the boundary condition on the reflection surface of the object to be detected, and it is usually unknown in what state the reflected wave returns. When detecting the rising edge of the waveform, it is desirable that the waveform always rises simultaneously with reception (that is, the phase is 0 °), such as the received wave b1 shown in the upper diagram of FIG. However, when the phase of the received wave b1 is shifted by 180 ° as in the received wave b2, the received signal rises after the half period Δt of the waveform from the time of reception. If an attempt is made to detect at the rising edge, a time error corresponding to Δt occurs, and therefore a distance accuracy error occurs.

  FIG. 4 shows a block configuration of the pulse radar apparatus according to the second embodiment, and FIG. 5 shows a transmission wave a and a rising detection target wave c in this apparatus. In the present embodiment, the uncertainty of the phase information of the reflected waveform depending on the reflection condition on the detection target described above can be removed. This apparatus is different from the apparatus shown in FIG. 1 described above in that the rising signal detection means 3 detects the rising edge of the signal obtained by taking the absolute value of the Doppler signal. That is, the received signal is mixed with the transmission signal by the mixing means 11, and the Doppler signal obtained by mixing is subjected to absolute value processing by the absolute value converter 4. The waveform rising detector 3 detects the waveform rising timing of the absolute value converted Doppler signal | D |. Similar to the above, the distance calculator 6 measures the time t from transmission to reception and obtains the distance to the object. This apparatus improves the distance accuracy compared to the apparatus and method shown in FIG.

  FIG. 6 shows a block configuration of the pulse radar apparatus according to the third embodiment, and FIGS. 7 and 8 show signal waveforms of respective parts in the apparatus. This apparatus removes the uncertainty of the phase information, and includes two mixing means 11 and 12 and two absolute value converters 41 and 42, and further includes a π / 2 phase shifter 9. The rising signal detection means 3 includes an absolute value output wave d1 obtained by processing the Doppler signal from the first mixing means 11 by the absolute value converter 41, a phase of the transmission signal 90 ° by the phase shifter 9, and the receiving antenna 8 The rising of the waveform (d1 + d2) of the sum signal of the absolute value output wave d2 obtained by mixing the received signal from the output signal by the second mixing means 12 with the absolute value converter 42 is detected. The distance calculator 6 measures the time t from transmission to reception to determine the distance to the object.

  In the apparatus of the present embodiment, as shown in FIGS. 7 and 8, the signal absolute value output wave d1 of the absolute value converter 41 and the signal absolute value output wave d2 of the absolute value converter 42 are added together. With this process, the rising target wave c to be processed by the rising signal detecting means 3 becomes a waveform that rises simultaneously with reception, regardless of the phase of the received wave. This device makes it possible to calculate the distance without error.

  FIG. 9 shows a block configuration of a pulse radar apparatus according to the fourth embodiment, and FIG. 10 shows signal waveforms of respective parts in the apparatus. This apparatus removes the uncertainty of the phase information, and is replaced with square converters 51 and 52 in place of the absolute value converters 41 and 42 in the apparatus shown in FIG. It is. The rising signal detection means 3 includes a square value output wave e1 obtained by processing the Doppler signal from the first mixing means 11 by the square converter 51, a transmission signal obtained by shifting the phase of the transmission signal by 90 °, and a receiving antenna. 8 detects a rising edge of the waveform (e1 + e2) of the sum signal of the squared value output wave e2 obtained by mixing the received signal from 8 by the second mixing means 12 and processing the Doppler signal by the square converter 52. . The distance calculator 6 measures the time t from transmission to reception to determine the distance to the object. With this device, the distance can be calculated without error as described above.

  The present invention is not limited to the above-described configuration, and various modifications can be made. For example, although the transmitting and receiving antennas are shown as separate antennas in each device explanatory diagram, an integrated type can also be applied. Moreover, although the thing including one and two mixing means was shown as a mixing means, you may make it provide three or more mixing means. In this case, the rising detection target wave may be formed by mixing a transmission signal that has undergone a phase shift other than 90 ° phase shift or a signal that has undergone a phase shift process with respect to the received signal. .

The block block diagram of the pulse radar apparatus which concerns on the 1st Embodiment of this invention. The wave form diagram of the transmission wave handled by an apparatus same as the above, and a rising detection object wave. The wave form diagram explaining the phase state of a received wave. The block block diagram of the pulse radar apparatus which concerns on the 2nd Embodiment of this invention. The wave form diagram of the transmission wave handled by an apparatus same as the above, and a rising detection object wave. The block block diagram of the pulse radar apparatus which concerns on the 3rd Embodiment of this invention. The wave form diagram explaining the synthesis | combination of the signal handled with an apparatus same as the above. The wave form diagram of the transmission wave handled by an apparatus same as the above, and a rising detection object wave. The block block diagram of the pulse radar apparatus which concerns on the 4th Embodiment of this invention. The wave form diagram of the transmission wave handled by an apparatus same as the above, and a rising detection object wave.

Explanation of symbols

2 Transmitter 3 Waveform rising detector (Signal detection means)
4, 41, 42 Absolute value converter 6 Distance calculator (ranging detection means)
7 Transmitting antenna 8 Receiving antenna 9 π / 2 phase shifter 11, 12 Mixing means 51, 52 Square converter

Claims (4)

  A transmission means for transmitting a transmission signal as a pulsed radio wave; a reception means for receiving a reflected wave formed by reflecting the radio wave transmitted by the transmission means on an object; and a reception signal from the reception means as the transmission signal. Mixing means for obtaining a Doppler signal by mixing, a rising signal detection means for outputting a detection signal when the rising edge of the Doppler signal reaches a preset threshold, and a distance to the object based on the output of the rising signal detection means A microwave pulse radar apparatus comprising: distance detection means for calculating the presence / absence of the object.   2. The microwave pulse radar device according to claim 1, wherein the rising signal detecting means includes means for detecting a rising edge of a signal obtained by taking an absolute value of the Doppler signal.   There are two mixing means, and the rising signal detecting means is a signal obtained by shifting the absolute value of the Doppler signal by the first mixing means and the transmission signal by 90 ° from the second mixing means and the receiving means. 2. The microwave pulse radar apparatus according to claim 1, wherein the rising of the sum signal of the absolute value of the Doppler signal obtained by mixing the received signal is detected.   There are two mixing means, and the rising signal detecting means is a signal obtained by shifting the square of the Doppler signal by the first mixing means and the transmission signal by 90 ° from the second mixing means and the receiving means. 2. The microwave pulse radar device according to claim 1, wherein the rising of the sum signal of the square of the Doppler signal obtained by mixing the received signal is detected.

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