JP2009092555A - Pulse radar apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve distance resolution and detection accuracy without increasing the scanning period in a pulse radar apparatus. <P>SOLUTION: When a target is not detected in the last update, a target is detected at a first distance resolution (low resolution: wide pulse width τ) in the whole measuring range. When a target is detected, the resolution is improved only in the area near the place where the target is detected, and a target is detected at a second distance resolution (high resolution: narrow pulse width τ). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pulse radar device that detects a distance to a target that reflects radar waves by transmitting and receiving pulsed radar waves.

  Conventionally, it is necessary for a radar wave to travel back and forth between the time it takes to transmit and receive a pulsed radar wave and transmit the radar wave to receive the reflected wave, that is, the distance to the target that reflects the radar wave. A pulse radar device that detects the distance to a target by measuring the measured time (hereinafter referred to as a round trip time) is known.

In addition, a technique using a matched filter is known as one method for measuring the round-trip time of a radar wave.
The pulse radar device to which this matched filter is applied generates a gate signal obtained by delaying a radar wave transmission signal by a preset delay time, and uses a correlator to correlate the gate signal with a reflected wave reception signal. Configured to ask for.

  Then, as shown in FIG. 8, the time width of the time range to be measured (hereinafter referred to as the measurement time range) is Ts, and the transmission of the radar wave is repeated with this time width Ts as the transmission period, and the delay of the gate signal A scan on the time axis is executed by repeating the measurement while sequentially changing the time D by a predetermined change amount τ (D = 0, τ, 2τ, 3τ...), And the correlator output is maximized. The delay time D of the gate signal at this time is detected as the round trip time of the radar wave.

  Note that the measurement time range (= radar wave transmission cycle) Ts is normally set to the time required for the radar wave to reciprocate the maximum detection distance R of the apparatus, and the speed of light is represented by equation (1). The

Ts = 2R / C (1)
When the distance resolution is ΔR, the distance resolution ΔR and the amount of change τ of the delay time D have the relationship shown in the equation (2).

τ = 2ΔR / C (2)
However, when the entire measurement time range Ts is scanned with the amount of change τ, the number of gate signals required for one scan, that is, the number of measurement repetitions N is expressed by equation (3), and The time required for scanning (scan cycle) Tscan is expressed by equation (4).

N = Ts / τ = R / ΔR (3)
Tscan = N × Ts (4)
That is, in order to improve the distance resolution ΔR (that is, to reduce ΔR), it is necessary to reduce the change amount τ of the delay time D and increase the number of repetitions N of measurements performed in one scan, Along with this, there is a problem that the scan time Tscan also increases.

  Specifically, when R = 68 m and ΔR = 0.1 m are set, N = 680 times and Tscan = 0.31 ms, and when ΔR = 0.05 m (distance resolution is doubled), N = 1360 times, Tscan = 0.62 ms (that is, N and Tscan are also doubled).

  Furthermore, in this type of pulse radar apparatus, the detection accuracy is improved by adding a plurality of scan results to a so-called synchronous addition gain. In this case, the information regarding the target detected by the radar is updated every time the scan is executed a plurality of times.

  As described above, when the scanning time Tscan is increased by improving the distance resolution, if the number of scans per update (and hence the synchronous addition gain) is to be secured, information on the target is obtained. The update cycle becomes longer and the real-time property of detection is impaired. On the other hand, if it is attempted to keep the update cycle constant in order to ensure the real-time property, the number of scans per update (and hence the synchronous addition gain) decreases, and the detection accuracy decreases.

That is, there is a problem that it is difficult to achieve both improvement in distance resolution and improvement in detection accuracy by the synchronous addition gain.
On the other hand, the distance resolution is not uniformly improved over the entire maximum detection distance R, but the distance resolution is high (τ is small) in the short distance region and the distance resolution is low (τ) (τ). A pulse radar device that detects a target has been proposed (see, for example, Patent Document 1).
JP 2006-90800 A

  In the apparatus described in Patent Document 1 (conventional apparatus), the distance resolution is increased only in the short-range area, so that the measurement performed in one scan is repeated as compared with the case where the entire detection area is increased in resolution. Although the increase in the number of return times N and the scan time Tscan can be suppressed, the number of repetition times N and the scan time Tscan remain unchanged, and the above-described problems can be alleviated and essentially solved. There was a problem that I could not.

  Moreover, for example, when a pulse radar device is mounted on a vehicle, it is not always necessary to have a high resolution only in the short-distance region, and depending on the situation of the vehicle, a high-resolution measurement may be required even in a long-distance region. There is a problem that the conventional apparatus cannot be applied in such a case.

  In order to solve the above problems, an object of the present invention is to improve both the distance resolution and the detection accuracy in a pulse radar device without increasing the scan time.

  In the pulse radar device of the present invention made to achieve the above object, the transmission signal generating means repeatedly generates a pulsed transmission signal at a preset transmission cycle, and the transmission / reception means is based on the transmission signal. A radar wave is transmitted and the reflected wave is received.

  Further, the gate signal generation means generates a gate signal obtained by delaying the transmission signal generated by the transmission signal generation means, and the correlation detection means is a reflected wave of the radar wave transmitted from the transmission / reception means received by the transmission / reception means. The correlation between the received signal and the gate signal generated by the gate signal generating means is obtained.

  At this time, the scanning unit sequentially changes the delay time of the gate signal generated by the gate signal generation unit for each transmission cycle, and the target detection unit transmits from the transmission / reception unit based on the detection result of the correlation detection unit. A target for reflecting the reflected radar wave is calculated.

  In the scanning unit, when the target is not detected by the target detection unit, the first setting unit sets the distance resolution of the target detected by the target detection unit to a first preset value. The delay time of the gate signal is changed at a rate corresponding to the distance resolution. Further, when the target is detected by the target detection means, the second setting means sets a designated section including the distance to the detected target, and the target detected by the target detection means The delay time of the gate signal is changed at such a ratio that the distance resolution of the target becomes the first distance resolution outside the designated section and becomes the second distance resolution set higher than the first distance resolution within the designated section. .

  The detection by the first setting means and the detection by the second setting means other than the designated section need only have a resolution that is rough enough to set the designated section. It is possible to keep it lower than the distance resolution used in the distance region.

  Further, since the second setting means obtains a high distance resolution (second distance resolution) only in the designated section, the number of measurement repetitions during one scan by setting the designated section. And the increase in scan time is minimized.

  In other words, according to the pulse radar apparatus of the present invention, the increase in scan time due to the setting of the designated section for detection with the second distance resolution is conventionally used as the first distance resolution used outside the designated section. It is possible to cancel out by lowering, and as a result, it is possible to realize target detection with high distance resolution without increasing the scan time as compared with the conventional apparatus.

  Moreover, in the pulse radar device of the present invention, the designated section for detection with the second distance resolution is not fixed to a specific area, but can be arbitrarily set, so that a high resolution can be achieved in a long distance area. Even a necessary use can be applied without any problem.

  The distance calculating means, as described in claim 2, adds a plurality of detection results obtained by the correlation detecting means to those detected based on gate signals having the same delay time. Based on this, it is desirable that the distance to the target is calculated.

  In this case, since the synchronous addition gain is obtained by using the addition value of the detection result, the S / N of the detection result of the correlation detection unit, and thus the detection accuracy (reliability) of the distance can be improved. In addition, as described above, according to the pulse radar device of the present invention, since the scan time is not increased, if the period for updating the detection result by the target detection unit is constant, The number of scans executed by the scanning means can be ensured to the maximum.

  Further, as described in claim 3, the transmission signal generating means outputs a transmission signal having a pulse width having the same magnitude as the amount of change in the delay time for each transmission period, according to the distance resolution realized by the scanning means. It is desirable to be configured to generate.

  In other words, if the pulse width is set to be greater than or equal to the change amount, the measurement range specified by the transmission cycle can be scanned without omission by the gate signal, but if the pulse width is set to the same magnitude as the change amount, Since gate signals do not overlap each other within the range, scanning can be performed efficiently.

  Next, in the pulse radar device according to claim 4, the speed acquisition unit acquires the moving speed of the moving body on which the device is mounted, and the scanning unit has at least one of the first distance resolution and the second distance resolution. One of them changes the delay time so as to have a magnitude corresponding to the movement speed acquired by the speed acquisition means. Specifically, for example, the first and second distance resolutions are set to be higher as the moving speed is lower.

According to the pulse radar device of the present invention configured as described above, the distance from the target can be detected with a resolution suitable for the moving speed.
Further, in the pulse radar device according to claim 5, when the speed acquisition means acquires the movement speed of the moving body on which the apparatus is mounted, and the movement speed is equal to or less than a preset speed threshold, the scanning means Is configured to change the delay time so that the distance resolution of the target detected by the target detection means becomes higher as the distance to the target is shorter.

  According to the pulse radar apparatus of the present invention configured as described above, when the moving speed of the moving body on which the apparatus is mounted is low, that is, there is a time margin until a long-distance target approaches, this is necessary. When it is not necessary to detect the urgently, it is possible to preferentially detect a short distance region with high resolution.

  Further, as described in claim 6, when the delay time is variably set by the third setting means, that is, when the moving speed of the moving body on which the apparatus is mounted is equal to or less than the speed threshold, the scanning means transmits It is desirable to change the delay time within a range that is shorter than the maximum delay time at low speed set shorter than the cycle. Here, the low speed maximum delay time is a maximum value of the delay time of the gate signal set when the speed of the moving body is equal to or lower than the speed threshold, and is set shorter than when the speed is equal to or higher than the threshold.

  According to the pulse radar device of the present invention configured as described above, when the moving body is moving at a low speed, the range in which the target is detected is limited. Therefore, the measurement is repeated within one scan. The number can be greatly reduced, and the distance to the target can be detected with high resolution over the entire limited range.

In the pulse radar device according to the seventh aspect, the target detection means calculates the relative speed of the target based on the calculation result of the distance to the target.
According to the pulse radar device of the present invention configured as described above, the relative speed can be accurately calculated based on the distance measured with high resolution (second distance resolution).

Embodiments of the present invention will be described below with reference to the drawings.
[First Embodiment]
<Configuration>
FIG. 1 is a block diagram illustrating a configuration of a pulse radar device 1 that is attached to a vehicle and detects a target (a preceding vehicle, an obstacle, or the like) existing in front of the vehicle.

  As shown in FIG. 1, a pulse radar device 1 includes an oscillator 11 that generates a high-frequency signal in the millimeter wave band, a timing signal ST that designates a timing for transmitting a radar wave, and a delayed timing signal obtained by delaying the timing signal ST. DST, a pulse control unit 12 that generates a pulse width signal PW that specifies the pulse width of the radar wave, and a high-frequency signal generated by the oscillator 11 based on the timing signal ST and the pulse width signal PW generated by the pulse control unit 12 Is generated at the timing specified by the timing signal ST for the period specified by the pulse width signal PW, and is generated by the transmission signal generating circuit 13 and the transmission signal generating circuit 13. A transmitter 14 that radiates a radar wave from the transmission antenna 15 by supplying the transmitted signal to the transmission antenna 15. Eteiru.

  The pulse radar device 1 includes a receiver 17 that receives a radar wave (reflected wave) transmitted from the transmission antenna 15 and reflected back to the target via the reception antenna 16, and a pulse control unit 12. By outputting the high frequency signal generated by the oscillator 11 based on the generated delay timing signal DST and the pulse width signal PW for the period specified by the pulse width signal PW at the timing specified by the delay timing signal DST. The gate signal generation circuit 18 that generates a pulsed gate signal and the reception signal of the reflected wave received by the receiver 17 are mixed with the gate signal generated by the gate signal generation circuit 18 to have the same frequency as the gate signal. Based on the correlator 19 for extracting the signal component having the signal, the detector 20 for detecting the output of the correlator 19, and the output (detection signal) of the detector 20. Together determine the distance and relative velocity of the target object to perform the reflection of da wave, and a signal processing unit 21 for executing target detection processing object to generate a command to the pulse control unit 12 based on the detection result.

<Configuration of pulse control unit>
The pulse control unit 12 is started and stopped in accordance with a start / stop command CA from the signal processing unit 21. At the time of startup, a timing generation unit 22 that generates a timing signal ST at a constant measurement cycle Ts, and a section from the signal processing unit 21 In accordance with the setting command RG, for each section indicated by the section setting command RG, the delay time signal DLT that defines the delay time D with respect to the timing signal ST of the delay timing signal DST and the pulse that defines the pulse width of the transmission signal and the gate signal The scan control unit 23 that outputs the width signal PW and the timing signal ST generated by the timing generation unit 22 are delayed by a delay time D defined by the delay time signal DLT output from the scan control unit 23. And a delay circuit 24 for generating a timing signal DST.

  Note that the cycle in which the timing generator 22 generates the timing signal ST, that is, the measurement cycle Ts, is set to the time required for the radar wave to reciprocate the maximum detection distance R of the pulse radar device 1, and the speed of light is C ( 5) It is expressed by the formula.

Ts = 2R / C (5)
The section setting command RG sets a time range defined by the measurement cycle Ts (hereinafter referred to as a measurement range) to either a low resolution section or a high resolution section. The scan control unit 23 that has received this section setting command RG is configured to output a delay time signal DLT and a pulse width signal PW that are set in advance for each section.

  At this time, the pulse width specified by the pulse width signal PW has a constant size for each section, while the delay time specified by the delay time signal DLT is pulsed every measurement period Ts. It is set to increase by the amount of change set to the same size as the width.

  Here, when the distance resolution is ΔR and the pulse width (change amount of the delay time) is τ, the two have the relationship shown in the equation (6). That is, the distance resolution ΔR is defined by the pulse width (change amount of delay time) τ.

τ = 2ΔR / C (6)
In the pulse radar device 1, the pulse width τ1 (and hence the first distance resolution ΔR1) in the low resolution section is set to a value larger than the pulse width τ2 (and thus the second distance resolution ΔR2) in the high resolution section. .

  If the length of the low resolution section in the measurement cycle Ts is T1 and the length of the high resolution section is T2 (Ts = T1 + T2), the number of measurement repetitions required for one scan (number of pulses generated) N is expressed by equation (7), and time Tscan required for one scan is expressed by equation (8).

N = T1 / τ1 + T2 / τ2 (7)
Tscan = N × Ts = (T1 / τ1 + T2 / τ2) × Ts (8)
<Target detection processing>
Next, the target detection process executed by the signal processing unit 21 will be described with reference to the flowchart shown in FIG.

When this process is started, first, in S110, a scan operation setting process for setting the content of the scan operation by outputting a section setting command RG to the scan control unit 23 is executed.
In subsequent S120, by outputting the start / stop command CA to the timing generation unit 22, the timing generation unit 22 is operated during the update period Trn determined from the content of the section setting command RG output in S110, and During the update period Trn, a scan process for acquiring the output of the detector 20 (hereinafter referred to as a correlation value) is executed every measurement cycle Ts.

  In addition, the update period Trn updates information on the target detected based on the measurement results obtained by M (M is an integer of 2 or more) scans, and is based on the contents of the section setting command RG (8) Using the Tscan obtained from the equation, it is calculated by the equation (9).

Trn = M × Tscan (9)
In continuing S130, the process which detects a target is performed based on the correlation value acquired by S120.

  Specifically, M correlation values obtained at the timing of the gate signal having the same delay time are added from M × N correlation values obtained by M scans, and the N additions are performed. A time region where the result (hereinafter referred to as an addition correlation value) is larger than a preset detection threshold is extracted as a region where the target exists.

In subsequent S140, it is determined whether or not a target has been detected as a result of the processing in S130, and if a negative determination is made (when no target is detected), the process returns to S110.
On the other hand, when an affirmative determination is made in S140 (when target detection is performed), the process proceeds to S150, and for each region in which the target is detected, the timing of the gate signal that maximizes the output in that region (radar) The time required for the radar wave to reciprocate the target is determined from the delay time with respect to the wave transmission timing. Note that the delay time of the gate signal may be used as the round trip time as it is, or the delay time may be obtained in detail from the distribution of the added correlation values.

  In subsequent S160, if the distance is calculated at the time of the previous update for the same target whose distance was calculated in S150, the vehicle equipped with the pulse radar device 1 is determined from the previous value and the current value. Is calculated, and the process returns to S110.

<Scan operation setting processing>
Next, the scan operation setting process executed in S110 will be described with reference to the flowchart shown in FIG.

  When this process is started, first, in S210, it is determined whether or not a target has been detected at the time of the previous update. If a negative determination is made (if no target is detected at the time of the previous update), the process proceeds to S220. Is set to the low resolution section, and the process proceeds to S240.

  On the other hand, if an affirmative determination is made in S210 (if the target is detected at the time of the previous update), the process proceeds to S230, and the closest target is extracted from the detected targets, with the distance as the center, A preset time region (for example, a range corresponding to ± 2 m centered on the detected distance) is set as a high resolution section, and other time regions are set as a low resolution section, and the process proceeds to S240.

In S240, the section setting command RG indicating the section set in S220 or S230 is output to the scan control unit 23, and this process is terminated.
The size of the high resolution section may always be a constant size, or may be changed according to the speed of the target. Moreover, you may comprise so that the area | region width before and behind with respect to the distance by which the target was detected changes according to the relative speed of a target.

<Effect>
As described above, in the pulse radar device 1, as shown in FIG. 4, until the target is detected, the entire range of the measurement range is set to the low resolution section, and the first distance resolution (low When the target is detected at the resolution (large pulse width) and the target is detected, the area near the target is set as the high resolution section. The target is detected in detail with a distance resolution of 2 (high resolution: pulse width is small).

FIG. 4 is a diagram schematically showing the relationship between the pulse width of the gate signal, the delay timing, and the detected distance from the gate signal.
That is, the first distance resolution may be a resolution that can set a high resolution section (corresponding to a designated section in the present invention), and can be suppressed to a low resolution. The high resolution section in which the detection is performed with the resolution is set only in the vicinity where the target is detected so that an increase in the scan time Tscan due to the setting is suppressed to a necessary minimum.

  Therefore, according to the pulse radar device 1, the increase in the scan time Tscan due to setting of the high resolution section is canceled by suppressing the resolution of the low resolution section (first distance resolution) lower than that of the conventional device. As a result, the target can be detected with a high distance resolution (second distance resolution) without increasing the scan time Tscan as compared with the conventional apparatus.

  Moreover, in the pulse radar device 1, the high resolution section for detecting the target with the second distance resolution is not fixed to a specific area within the measurement range, but is possible in all areas. Even applications that require high resolution in the region can be applied without problems.

  Further, according to the pulse radar device 1, the distance to the target is obtained using the added correlation value obtained by adding the correlation values obtained by M scans with the same delay time of the gate signal. Therefore, the distance detection accuracy (reliability) can be improved by the synchronous addition gain.

  In addition, as described above, according to the pulse radar device 1, the detection of the target with high distance resolution is realized without increasing the scan time Tscan, and therefore the update period of information regarding the detected target is constant. If so, the effect of the number of scans M to be executed during the update cycle, and hence the synchronous addition gain, can be ensured to the maximum.

In this embodiment, the oscillator 11, the timing generation unit 22, and the transmission signal generation circuit 13 correspond to transmission signal generation means, and the transmitter 14, the transmission antenna 15, the reception antenna 16, and the receiver 17 correspond to transmission / reception means. The oscillator 11, the timing generator 22, the delay circuit 24, and the gate signal generator 18 correspond to the gate signal generator, the correlator 19 and the detector 20 correspond to the correlation detector, and the scan controllers 23a and S110 scan. S120 to S160 correspond to the target detection means, S220 and the scan control unit 23 that operates according to the section setting command RG corresponding thereto correspond to the first setting means, and S230 and the section corresponding thereto The scan control unit 23 that operates according to the setting command RG corresponds to the second setting means.
[Second Embodiment]
A second embodiment will be described.

FIG. 5 is a block diagram showing a configuration of the pulse radar device 3 of the present embodiment.
In the pulse radar device 3, only the configurations of the pulse control unit 12 a (particularly the scan control unit 23 a) and the signal processing unit 21 a are different from those of the first embodiment. A description thereof will be omitted, and this different part will be mainly described.

<Signal processing unit>
The signal processing unit 21a obtains the speed (hereinafter referred to as vehicle speed) V of the vehicle on which the device 3 is mounted from a vehicle speed sensor (not shown), and only sends the section setting command RG to the scan control unit 23a. The mode setting command MD and the resolution setting command PS are output.

  The operation mode set by the mode setting command MD includes a normal mode set when the vehicle speed V is larger than a preset speed threshold Vth (20 km / h in this embodiment), and the vehicle speed V is the speed. There is a low-speed mode that is set when the threshold Vth or less.

<Scan control unit>
As shown in FIG. 7, when the normal mode is specified by the mode setting command MD, the scan control unit 23a operates in the same manner as the scan control unit 23 of the first embodiment. However, for the pulse width specified by the pulse width signal PW and the amount of change in the delay time of the gate signal, values corresponding to the distance resolution specified by the resolution setting command PS are used.

  On the other hand, when the low speed mode is designated by the mode setting command MD, the scan control unit 23a sets the time range required for the radar wave to reciprocate the low speed maximum detection distance RL set shorter than the maximum detection distance R. A delay time signal DLT and a pulse width signal PW for executing a scan only in the measurement interval are output with the measurement interval and the rest as non-measurement intervals.

  However, the pulse width specified by the pulse width signal PW increases by a preset change amount every measurement cycle Ts, while the delay time specified by the delay time signal DLT is specified by the previous measurement cycle. The measured pulse width is set as the amount of change, and the amount of change is set to increase every measurement period Ts. That is, it operates so as to realize a scan in which a target is detected with a higher distance resolution as the distance is shorter.

  Here, the amount of change in the pulse width and the delay time is continuously increased for each measurement period Ts. However, the measurement interval is divided and configured to increase stepwise for each divided interval. May be.

<Scan operation setting processing>
Next, the scan operation setting process executed by the signal processing unit 21a will be described with reference to the flowchart shown in FIG.

When this process is started, first, in S310, the vehicle speed V of the host vehicle is acquired, and in subsequent S320, it is determined whether or not the acquired vehicle speed V is greater than the speed threshold value Vth.
If it is determined that the vehicle speed V is greater than the speed threshold Vth, the process proceeds to S330 and the operation mode is set to the normal mode.

In continuing S330, it is judged whether the target was detected at the time of the last update.
If a negative determination is made in S330, that is, if no target is detected, the process proceeds to S350, the entire section is set as a low resolution section, and the process proceeds to S380.

  On the other hand, if an affirmative determination is made in S340, that is, if a target has been detected, the process proceeds to S350, and the closest detected target is extracted and centered on that distance. A certain time region is set as a high resolution section, and the other time regions are set as a low resolution section.

  In subsequent S370, based on the vehicle speed V detected in S310 and the distance to the target detected in S150, the resolution of the high resolution section (that is, the second distance resolution) is set, and the process proceeds to S380. The second distance resolution is set using a table stored in advance so that the lower the vehicle speed V is, the higher the resolution is as the distance to the previously detected target is shorter.

  In S380, based on the vehicle speed V detected in S310, the resolution of the lower resolution section (that is, the first distance resolution) is set as the vehicle speed V is lower, and the process proceeds to S410. The first distance resolution is set using a prestored table or the like so that the higher the vehicle speed V, the higher the resolution.

If a negative determination is made in the previous 320, that is, if the vehicle speed V is equal to or lower than the speed threshold Vth, the process proceeds to S390, and the operation mode is set to the low speed mode.
In subsequent S400, the size and resolution of the measurement section are set based on the vehicle speed V acquired in S310, and the process proceeds to S410. It should be noted that the measurement section is set using a table stored in advance so that the measurement interval is shorter as the vehicle speed V is lower and the resolution is higher as the vehicle speed V is lower. However, in the low speed mode, the resolution changes continuously, so the initial value is set.

  In S410, the mode setting command MD for specifying the operation mode set in S330 or S390, the section setting commands RG, S370 and S380, or S400 for specifying the section set in S350, S360, or S400 are set. A resolution setting command PS for designating the resolution is output to the scan control unit 23a, and this process is terminated.

<Effect>
As described above, according to the pulse radar device 3, the normal mode (V ≦ Vth) operates in the same manner as the pulse radar device 1 of the first embodiment, so that the same effect can be obtained. it can.

  Further, in the pulse radar device 3, when in the low speed mode (V> Vth), the measurement section that is the range in which the scan is executed is limited, and the target is detected with higher distance resolution as the distance is shorter in the measurement section. Has been.

  Therefore, according to the pulse radar device 3, it is possible to preferentially detect a short-distance area with high resolution when there is no need to quickly detect a long-distance target. Moreover, since the number of measurement repetitions N in one scan can be greatly reduced by limiting the measurement interval, if the cycle for updating the target information is made constant, the update cycle By increasing the number of scans, the synchronous addition gain can be increased, and the distance and relative speed detection accuracy can be improved.

In this embodiment, S310 corresponds to the speed acquisition unit, and the scan control unit 23a that operates according to S390 to S400 and the mode setting command MD corresponding thereto corresponds to the third setting unit.
[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, in the above embodiment, the high resolution section is set only for the target located at the shortest distance among the detected targets, but the high resolution section is set for a plurality of targets. You may comprise.

  In the first embodiment, the distance resolutions of the low resolution section and the high resolution section are fixed, respectively. However, similarly to the second embodiment, the distance resolution may be variably set according to the vehicle speed and distance. Good.

  Conversely, in the second embodiment, the distance resolution is variably set according to the vehicle speed and distance in both the low resolution section and the high resolution section set in the normal mode, but only in one of the sections. It may be configured to variably set or to fix the distance resolution in any section.

  In the above embodiment, the scan control units 23 and 23a are provided separately from the signal processing units 21 and 21a, but the delay time signal DLT and the pulse width signal PW are generated by the processing of the signal processing unit 21. It may be configured.

The block diagram which shows the structure of the pulse radar apparatus 1 of 1st Embodiment. The flowchart which shows the content of the target detection process. The flowchart which shows the content of a scanning operation | movement setting process. Explanatory drawing which shows operation | movement of the scan control part 23. FIG. The block diagram which shows the structure of the pulse radar apparatus 3 of 2nd Embodiment. The flowchart which shows the content of a scanning operation | movement setting process. Explanatory drawing which shows operation | movement of the scan control part 23a. Explanatory drawing which shows operation | movement of the pulse radar apparatus which detects with a matched filter.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,3 ... Pulse radar apparatus 11 ... Oscillator 12, 12a ... Pulse control part 13 ... Transmission signal generation circuit 14 ... Transmitter 15 ... Transmission antenna 16 ... Reception antenna 17 ... Receiver 18 ... Gate signal generation circuit 19 ... Correlator 20 ... detectors 21, 21a ... signal processing unit 22 ... timing generation unit 23, 23a ... scan control unit 24 ... delay circuit

Claims (7)

Transmission signal generation means for repeatedly generating a pulsed transmission signal at a preset transmission cycle;
Transmitting / receiving means for transmitting a radar wave based on the transmission signal and receiving the reflected wave;
Gate signal generating means for generating a gate signal obtained by delaying the transmission signal generated by the transmission signal generating means;
Correlation detection means for obtaining a correlation between a reception signal that is a reflected wave of a radar wave transmitted from the transmission / reception means received by the transmission / reception means, and a gate signal generated by the gate signal generation means;
Scanning means for sequentially changing the delay time of the gate signal generated by the gate signal generating means for each transmission period;
Based on the detection result in the correlation detection means, target detection means for detecting a target that reflects the radar wave transmitted from the transmission / reception means;
In a pulse radar device comprising:
The scanning means includes
A first setting means for changing the delay time at a rate such that the distance resolution of the target detected by the target detection means becomes a preset first distance resolution;
When the target is detected by the target detection means, a designated section including the distance to the target is set, and the distance resolution of the target detected by the target detection means is the specified section. A second setting means for changing the delay time at a rate that becomes the first distance resolution outside and the second distance resolution set higher than the first distance resolution within the specified section;
A pulse radar device comprising:   The target detection means detects the target based on a result obtained by adding a plurality of detection results obtained by the correlation detection means based on gate signals having the same delay time. The pulse radar device according to claim 1, wherein:   The transmission signal generation unit generates a transmission signal having a pulse width equal to the amount of change in the delay time for each transmission period in accordance with the distance resolution realized by the scanning unit. The pulse radar device according to claim 1 or 2. Comprising a speed acquisition means for acquiring the moving speed of the moving body equipped with the device;
The scanning unit changes the delay time so that at least one of the first distance resolution and the second distance resolution has a magnitude corresponding to the moving speed acquired by the speed acquiring unit. The pulse radar device according to any one of claims 1 to 3, wherein the pulse radar device is characterized by the following. Comprising a speed acquisition means for acquiring the moving speed of the moving body equipped with the device;
The scanning means includes
When the moving speed acquired by the speed acquisition unit is equal to or lower than a preset speed threshold, the distance resolution of the target detected by the target detection unit is such that the shorter the distance to the target is, 4. The pulse radar device according to claim 1, further comprising third setting means for changing the delay time so as to increase.   The scanning unit, when performing the variable setting of the delay time by the third setting unit, changes the delay time within a range that is less than or equal to the maximum delay time at low speed set shorter than the transmission cycle. The pulse radar device according to claim 5.   The pulse radar device according to claim 1, wherein the target detection unit calculates a relative speed of the target based on a calculation result of a distance to the target. .

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