JP2003329764A - Pulse radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a pulse radar system that can correctly detect a target within the range of the Radio Law now in force even if there is a reflection signal from targets fixed to a radar such as a leakage signal between transmission and reception or radome. <P>SOLUTION: The pulse radar system comprises a transmission means 501 for transmitting pulsed radio waves, a reception means 502 for receiving reflection wave of transmitted radio waves and for outputting a beat signal, a sampling means 504 for sampling the beat signal at a specific time interval from the transmitter, an FFT operation means 505 for allowing the sampled result to be subjected to FFT operation for each sampling timing, a detection decision means 506 for deciding the presence or absence of the target based on output from the FFT operation means, a distance/relative speed operation means 508 for calculating distance and a relative speed to the target, and a timing control means 509 for controlling the timing of the transmission and reception of the radio waves and signal processing. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention transmits radio waves,
The present invention relates to a pulse radar device that detects the presence or absence of a target by receiving a reflected wave of the transmitted radio wave reflected by the target, and measures the distance and relative speed to the detected target.

[0002]

2. Description of the Related Art As a conventional pulse radar device, there is one proposed in Japanese Patent Laid-Open No. 7-72237. In this device, as shown in FIG. 17, the pulse signal sending means 101 periodically outputs a pulsed signal. Then, the reflected pulse from the target is continuously received by the reflected pulse signal receiving means 103 and binarized by the binarizing means. And sampling means 104
However, after the transmission timing of the transmission means 101, the binarized signal is sampled at every fixed one or a plurality of sampling points to obtain a sampling value of 0 or 1, and this is added to each sampling point.・ Memory means 10
Give to 5. Therefore, the adding / storing means 105 adds the sampling value of 0 or 1 by the predetermined number of times of sending the pulse signal by the sending means 101. When the addition processing for the predetermined number of times is completed, the determination means 106 causes the addition / storage means 10
The normalized addition value obtained by dividing the addition value for each 5 by the number of additions is compared with a predetermined threshold value, and it is determined whether or not a reflection signal from an external target is present based on the magnitude of the addition value. Based on this, the presence or absence of an external target is determined. 10
2 is a pulse signal transmitting means 101 and a sampling means 10
4, control means for controlling the addition / storage means 105 and the determination means 106.

[0003]

By the way, when the isolation between transmission and reception is poor and there is a so-called leak waveform, or when there is a radome, the above device is used for less than 10 m due to the following reasons. It is difficult to detect a target existing at a distance and measure a distance to the target. That is, in the proposed device, the transmission pulse width is 66.7 ns, which corresponds to a distance of 10 m. Therefore, as shown in FIG.
When the target exists at a distance closer than 10 m, a leak waveform or a waveform in which the reflected wave from the secondary radome and the reflected wave from the target overlap each other is detected.
Therefore, if the threshold value is set based on the reception level during non-transmission, that is, the so-called noise level, only the rising edge of the leak waveform can be detected, and the rising edge of the reflected wave that one really wants to detect cannot be detected.

As a measure against these problems, W. Weidma
nn and D. Steinbuch, “High Resolution Radar for Sho
rt Range Automotive Applications ", 28 ^th European Mi
As described in crowave Conference Amsterdam, 1998,
As described in Japanese Patent Application Laid-Open No. 10-62518, a method of making the pulse width extremely short such as 350 ps,
A method of canceling a leak waveform by using a transmission waveform has been proposed. When the transmission pulse width is shortened to 350 ps as described in the former document, the leak waveform and the reflected wave waveform overlap only when the distance to the target is about 5 cm or less, so the above-mentioned problem is solved. However, since the occupied bandwidth becomes extremely wide, there is a problem that it cannot be used within the range of the current Radio Law. Also,
In the case of the method of canceling the leakage waveform by utilizing the transmission waveform as in Japanese Patent Laid-Open No. 10-62518, the difference in time interval between transmission and reception of the leakage waveform due to individual difference or difference in use condition, and size of leakage waveform. There is a problem in that it is difficult to deal with differences in the situation and it is necessary to adjust according to the situation.

[0005]

The present invention has been invented in order to solve the above problems, and as shown in FIG. 2, a leak signal between transmission and reception, or a radar such as a radome is used. Using the fact that the received signal changes when the phase difference between the reflected signal from the fixed target and the reflected signal from the moving target changes.
The present invention realizes a pulse radar device that can correctly detect a target within the scope of the current Radio Law even if there is a leak signal between the transmission and reception or a reflection signal from a target fixed to the radar such as a radome.

[0006]

According to a first aspect of the present invention, there is provided a pulse radar device comprising a transmitting means for transmitting pulsed radio waves, and a reflected wave in which the radio waves transmitted from the transmitting means are reflected by a plurality of targets. The receiving means for receiving and outputting the beat signal, the sampling means for sampling the beat signal at a predetermined time interval from the transmission, the FFT calculating means for calculating the FFT of the sampling result at each sampling timing, and the FFT calculating means. Detection / determination means for determining the presence / absence of a target based on the output of the target, distance / relative speed calculation means for calculating the distance to the target and relative speed, and timing control for performing timing control of radio wave transmission, reception and signal processing And means.

A pulse radar device according to a second aspect of the present invention receives a beat by receiving a transmitting means for transmitting a pulsed radio wave and a reflected wave in which the radio wave transmitted from this transmitting means is reflected by a plurality of targets. The receiving means for outputting the signal, the sampling means for sampling the beat signal at a predetermined time interval from the transmission, the FFT calculating means for performing the FFT operation on the sampling result at each sampling timing, and the output from the FFT calculating means are also included. Detection detection means for determining the presence or absence of a target, a discrimination means for discriminating the target, a distance / relative speed calculation means for calculating a distance to the target and a relative speed, and transmission of radio waves,
And a timing control means for performing timing control of reception and signal processing.

A pulse radar device according to a third aspect of the present invention receives a beat signal by receiving a transmitting means for transmitting a pulsed radio wave and a reflected wave in which the radio wave transmitted from this transmitting means is reflected by a plurality of targets. A receiving means for outputting, a sampling means for sampling a beat signal at a predetermined time interval from transmission, an FFT calculating means for performing an FFT operation on the sampling result at each sampling timing, and an output from the FFT calculating means. Detection / determination means for determining the presence / absence of a target, discrimination means for discriminating the target, distance / relative speed calculation means for calculating the distance to the target and relative speed, and timing control of radio wave transmission, reception, and signal processing Timing control means, vehicle speed detection means for detecting the speed of the own vehicle, and unnecessary signals such as roads are removed. It is characterized in that a required signal removing means.

In the pulse radar device according to claim 2 or 3 of the present invention, the discriminating means for discriminating the target discriminates the target using the peak frequency obtained from the FFT calculating means. To do.

In the pulse radar device according to a fourth aspect of the present invention, when the discriminating means discriminates the target in order from the sampling timing corresponding to the short distance, the peak frequency of the detected target is the frequency at which the peak frequency is detected for the first time. In this case, it is characterized by having a distance / relative speed calculating means for calculating the distance to the target from the sampling timing and for calculating the relative speed to the target from the frequency.

In the pulse radar device according to the fourth aspect of the present invention, when the discriminating means discriminates the targets in order from the sampling timing corresponding to the short distance, the peak frequency of the detected target is the frequency at which the peak frequency is detected for the first time. In that case, it is necessary to have a distance / relative velocity calculation means that determines the distance to the target from the ratio of the sampling timing and the peak level of the same frequency obtained at the next sampling point, and the relative velocity with the target from that frequency. It is a feature.

A pulse radar device according to a seventh aspect of the present invention receives a beat signal by receiving a transmitting means for transmitting a pulsed radio wave and a reflected wave in which the radio wave transmitted from this transmitting means is reflected by a plurality of targets. The receiving means for outputting, the comparator means for binarizing the signal from the receiving means with a predetermined level set in advance, the output of the comparator means at a predetermined time interval from transmission, and the sampling result is sampled. Received signal integrating means for integrating a predetermined number of times at each sampling timing, and an FF for performing an FFT operation by reading out the integrated result of the received signal integrating means at each sampling timing at every predetermined time.
T calculation means, detection determination means for judging the presence or absence of a target based on the output from this FFT calculation means, distance / relative speed calculation means for calculating the distance to the target and relative speed, transmission of radio waves, And a timing control means for performing timing control of reception and signal processing.

A pulse radar device according to an eighth aspect of the present invention receives a beat signal by transmitting means for transmitting a pulsed radio wave and a reflected wave in which the radio wave transmitted from this transmission means is reflected by a plurality of targets. The receiving means for outputting, the comparator means for binarizing the signal from the receiving means with a predetermined level set in advance, the output of the comparator means at a predetermined time interval from the transmission, and the sampling result Of the received signal integrating means for integrating a predetermined number of times at every sampling timing, an FFT calculating means for reading out the integrated result of the received signal integrating means at each sampling timing for every predetermined time, and an FFT calculating means. Based on the output, the target is discriminated from the detection determination means that determines the presence or absence of the target. It is characterized in that it is provided with a discriminating means, a distance / relative speed calculating means for calculating a distance to the target and a relative speed, and a timing control means for performing timing control of transmission, reception and signal processing of radio waves. .

A pulse radar device according to a ninth aspect of the present invention receives a beat signal by transmitting means for transmitting a pulsed radio wave and a reflected wave in which the radio wave transmitted from this transmission means is reflected by a plurality of targets. The receiving means for outputting, the comparator means for binarizing the signal from the receiving means with a predetermined level set in advance, the output of the comparator means at a predetermined time interval from the transmission, and the sampling result Of the received signal integrating means for integrating a predetermined number of times at every sampling timing, an FFT calculating means for reading out the integrated result of the received signal integrating means at each sampling timing for every predetermined time, and an FFT calculating means. Based on the output, the target is discriminated from the detection determination means that determines the presence or absence of the target. Discrimination means, distance / relative speed calculation means for calculating the distance to the target and relative speed, timing control means for controlling the timing of radio wave transmission, reception, and signal processing, and vehicle speed detection means for detecting the speed of the host vehicle. And an unnecessary signal removing means for removing an unnecessary signal such as a road.

In the pulse radar device according to claim 8 or claim 9 of the present invention, the discriminating means for discriminating the target discriminates the target by using a peak frequency obtained from the FFT calculating means. To do.

In the pulse radar device according to the tenth aspect of the present invention, when the discriminating means discriminates the targets in order from the sampling timing corresponding to the short distance, the peak frequency of the detected target is the frequency at which the peak frequency is detected for the first time. In this case, it is characterized by having a distance / relative speed calculating means for calculating the distance to the target from the sampling timing and for calculating the relative speed to the target from the frequency.

In the pulse radar device according to the tenth aspect of the present invention, when the discriminating means discriminates the targets in order from the sampling timing corresponding to the short distance,
When the peak frequency of the detected target is the frequency that is detected for the first time, the distance to the target is calculated from the ratio of the sampling timing and the peak level of the same frequency obtained at the next sampling point. It is characterized by having a distance / relative speed calculation means for obtaining a relative speed.

In the pulse radar device according to any one of claims 7 to 12, the ground level changing means for changing the ground level of the received signal according to the integrated result of the received signal integrating means. It is characterized by the addition of.

In the pulse radar device according to the thirteenth aspect of the present invention, the ground level changing means outputs a signal when the average value of the integration result of each sampling timing by the reception signal integrating means exceeds a predetermined range. Is controlled by a ground level control means for outputting

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the pulse radar device according to the present embodiment is roughly 5
It consists of two parts. That is, a predetermined width, for example, 9
6 ns pulsed electromagnetic wave (center frequency 24.125G
(Hz) at a constant cycle, for example, 1024 ns, and an RF module 1 composed of a transmitting means 501 and a receiving means 502 for receiving a reflected wave of an electromagnetic wave from a peripheral object (target), and a signal received by the receiving means 502 is A comparator circuit including an adder circuit 2 including a ground level changing unit 511 that changes a ground level based on an instruction from a CPU described later so as not to be saturated, and a comparator unit 503 for binarizing an output of the adding circuit 2. 3, a field programmable gate array (= FPG) that includes timing control means 509 and received signal integration means 504 and functions as sampling means.
The CPU 5 includes a fast Fourier transform (abbreviated as AFT) calculation unit 505, a detection determination unit 506, a target discrimination unit 507, a distance / relative speed calculation unit 508, and a ground level control unit 510.

Here, an example is shown in which the received signal is binarized and integrated, but the received signal is A / D converted and the CPU 5
The configuration may be such that FFT calculation, detection determination, target discrimination, and distance / relative speed calculation are performed.

First, the structure of the RF module 1 is shown in FIG. The signal of 10.8375 GHz by the oscillator 601 is divided into two by the power distributor 602, one of which is the mixer 6
At 03, the signal is mixed with the 1.225 GHz signal by the oscillator 604, and then at the modulator 605, a pulsed signal is generated based on the transmission signal. Next, it is multiplied by 2 in the multiplier 606, and is passed through the filter 607 to 24.125.
It becomes a signal of GHz and is radiated outside as a radio wave from the transmitting antenna 608. The radio wave reflected by the external target is received by the receiving antenna 609, amplified by the RF amplifier 610, mixed in the mixer 611 with the signal from the oscillator 601, and dropped to a middle frequency as a beat signal. After that, the signal is subjected to envelope detection by the detector 615 through the intermediate frequency amplifier 612, the filter 613, and the amplifier 614, and becomes a reception signal.

Next, FIG. 4 (a) shows the internal structure of the FPGA 4 including the timing control means 509 and the received signal integration means 504 and functioning as the sampling means, and FIG. 4 (b) shows its operation timing chart.

Referring to FIGS. 4A and 4B, this FPGA 4 is provided with a timing control means 509 and a reception signal integration means 504, which are each bit of the timing control circuit 11, the shift register 12, and the shift register 12. K1 to Kn and integration register R1 corresponding to
To Rn. Timing control circuit 11
Is a clock signal a generated by an oscillator from outside the FPGA4.
Based on (for example, 125 MHz = 8 ns cycle), a transmission signal b (for example, width 96 ns, cycle 1024 ns) for the transmission means 501 to turn on / off the electromagnetic wave emission, and a timing for bit-shifting with respect to the shift register 12 described later. A shift signal d to be transmitted, an addition signal e to transmit addition timing to the adders K1 to Kn, and an integration signal e to transmit timing to hold outputs of the adders K1 to Kn to integration registers R1 to Rn, C is the end of the integration process
The integration process end signal f transmitted to the PU 5 is generated. The shift register 12 stores the binarized data of the reception signal output from the comparator circuit 503 while shifting bit by bit based on the shift signal d of the timing control circuit 11. The adders K1 to Kn add the binary data (0 or 1) of each bit and the contents of the integration registers R1 to Rn according to the addition signal e from the timing control circuit 11. The accumulation registers R1 to Rn hold the outputs from the adders K1 to Kn as accumulated data, and
When there is a request from U5, the contents of the integration register are output.

Next, the operation of the FPGA 4 will be described. First, the transmission signal b is raised on the basis of the external clock signal a and falls 10 clocks later. Simultaneously with the rise of the transmission signal b, the shift signal d synchronized with the clock signal a is output by the number of bits of the shift register 12. Based on this shift signal d, the shift register 12 holds the binarized data (received signal) c output from the comparator circuit 3 in each bit. Then, after outputting the shift signal d for the number of bits of the shift register 12, the addition / integration signal e is output. Based on this signal, the adders K1 to Kn and the accumulation registers R1 to Rn respectively hold addition / accumulation data. Then, a predetermined number of times (for example, 1000 times),
After repeating this operation, the integration processing end signal f is output to the CPU 5. When receiving the integration processing end signal f, the CPU 5 reads the contents of the integration registers R1 to Rn.

Subsequently, FFT calculation means 505, detection determination means 506, target discrimination means 507, distance / relative speed calculation means 508, and ground level control means 510.
The processing in the CPU 5 having the will be described.

As shown in FIG. 5, the CPU 5 first initializes the inside of the CPU 5 in step 801. Then, after initializing the data in step 802, in step 803, the integration processing end signal from the FPGA 4 is waited for. F
When the integration process end signal from PGA4 is received, the integration result at each sampling timing is set to F in step 804.
It is stored in a two-dimensional array called PGA [i] [j]. Here, i (= 0 to N; N is the number of bits of the shift register 12) is the sampling timing, and j (= 0 to 63; the number of stored data is 64 times) is the storage order.

When the number of times the integration processing end signal f is received from the FPGA 4 reaches a predetermined number (here, 64 times), the processing from step 805 to step 806, that is,
Grant level control processing (step 806), FFT calculation processing (step 807), detection determination processing (step 8)
08), target discrimination processing (step 809), and distance / relative velocity calculation processing (step 810). afterwards,
In step 811, it is confirmed whether or not the processing cycle of 50 ms has elapsed, and if so, step 802
Return to and repeat the same operation.

The ground level control processing in step 806 will be described in more detail. As shown in FIG. 6, when a threshold value is set at the position A in the figure and binarization is performed, the value is always 1 regardless of the presence or absence of the peripheral target, and the target cannot be detected. The ground level control process is a process for adjusting the ground level of the received signal to raise or lower the entire received signal so that the threshold value comes to the position B in the figure.

FIG. 7 shows a flowchart of the ground level control process. Step 1001 to Step 1009
In the process of, the sum Sum [i] of the integrated values of 64 times at each sampling timing is obtained. Next Step 10
10 is the sum S of integrated values at each sampling timing
An average value SumMean of um [i] is calculated. In step 1010, SumMean and a preset value S
Compared with UMMEAN1, if SUMMAN1 is smaller, the instruction value to the adder circuit 2 which is the grant level changing unit 511 is decreased in step 1012. On the other hand, if it is larger than SUMMEAN1, step 101
SumMean and SUMMEAN2 in 1 (however, SU
MMEA1> SUMMEAN2)
If the EAN2 is larger, the instruction value to the adder circuit 2 which is the ground level changing means 511 is increased in step 1014. If SUMMEAN2 is smaller, the previous instruction value is held as it is in step 1013. Then, in step 1015, the instruction value is D / A converted and output from the CPU 5, and the adder circuit 2 adds the received signal to adjust the ground level of the received signal. In this embodiment, the position of the threshold value is adjusted by changing the ground level of the received signal, but the threshold value itself may be controlled.

The FFT calculation process in step 807 of FIG. 5 will be described in more detail. As shown in FIG. 8, the phase of the portion where the leak signal between the transmitter and the receiver or the reflected signal from the target fixed to the radar such as the radome and the reflected signal from the moving target are superposed changes. In order to do so, its level changes depending on the relative speed of the target. In FIG. 8, the time is from t = T1 to T4.
It shows that the level of the above-mentioned overlapped portion changes while changing to. Now, when the rate of change, that is, the frequency is fa [Hz], it is expressed by the following equation 1. fa = (2 × V / c) × fo (Formula 1) However, V: relative velocity of target [m / s], c: speed of light × 104 [m / s], fo: carrier frequency [Hz] Therefore, ( From Equation 1), the relative velocity of the target is expressed by Equation 2 below. V = (c / (2 × fo)) × fa (Equation 2) Therefore, focusing on a point after a certain time from the transmission timing and performing FFT arithmetic processing on the time-series data, the absolute relative velocity of the target from the peak frequency is calculated. You can know the value.

The same applies to the result of binarizing the received signal using the comparator and integrating the signal a predetermined number of times. As shown in FIG. 9, the reception signal Rx is provided with a first threshold value, binarized, and integrated a predetermined number of times, for example 1000 times. Of this integration result, the phase difference changes in the portion where the leak signal between the transmitter and receiver or the reflected signal from the target fixed to the radar such as radome and the reflected signal from the moving target are superimposed. In order to do so, its level changes according to the relative speed of the target. Therefore,
The time series data (64 data in FIG. 9) of the integration result is FF
By performing the T calculation process, the absolute value of the relative velocity of the target can be similarly known.

FIG. 10 shows a flowchart of the FFT calculation process. First, in step 1301, the sampling timing of interest is initialized. In the next step 1302, the FP in which the sampling timing of interest is stored
The output data from the GA4 (output from the reception signal integrating means 504) is subjected to FFT calculation, and the result is FF.
It is stored in a two-dimensional array called T [i] [j]. Step 13
In 03, advance the sampling timing of interest,
In step 1304, it is checked whether FFT calculation processing has been performed for all sampling timings,
If not all, it returns to step 1302 and performs the same processing. If the FFT calculation processing has been completed for all sambling timings in step 1304, the processing ends.

In the detection determination processing of step 808 of FIG. 8, among the outputs from the FFT integration processing of step 807, those exceeding a preset level are determined to have a target.

Next, the target discrimination processing in step 809 of FIG. 5 will be described in more detail. For example, in FIG.
In the case where the vehicle 1 and the vehicle 2 are running side by side with respect to the vehicle 0 equipped with the pulse radar device as in 1,
By the detection determination process of step 808, nothing is detected at the sampling timing 0, but at the sampling timing 1, the frequency component due to the reflection of the road surface or the like is detected. Therefore, it is determined that a new target exists at the sampling timing 1. Similarly, when the sampling timings 2, 3, ... Are sequentially examined for the detection determination processing result, a new frequency component due to the reflection from the vehicle 1 is detected at the sampling timing 4. Therefore, it is determined that a new target exists at the sampling timing 4. Similarly, since a new frequency component due to reflection from the vehicle 2 is detected at the sampling timing 8, it is determined that a new target exists at the sampling timing 8. Target discrimination is performed as described above.

FIG. 12 shows a flowchart of the target discrimination processing. First, in step 1501, the sampling timing of interest is initialized. Then step 150
In step 2, it is checked whether or not there is a new frequency peak detected by the detection determination processing in step 808. If there is a new frequency peak, step 150
In step 3, the target existence flag [i] at that sampling timing is set, and the process proceeds to step 1504. If there is no new frequency peak, step 150.
In step 4, the sampling timing of interest is advanced by one, and in step 1505, it is checked whether or not the above processing has been performed at all sampling timings. If not, the processing returns to step 1502 and the above processing is performed. When the processing is completed at all sampling timings, the target discrimination processing is completed.

Next, the distance / relative velocity calculation processing in step 810 of FIG. 5 will be described in more detail. The distance is calculated from the sampling timing when it is determined that the target is present in the target discrimination processing in step 809,
The relative speed is calculated from the peak frequency.

FIG. 13 shows a flowchart of the distance / relative velocity calculation processing. First, in step 1601, the sampling timing of interest is initialized. Step 160
In 2, save the information of distance and relative velocity obtained last time,
In step 1603, the target number k is initialized, and the distance and relative velocity information is initialized (Dist [k] = end detection equivalent distance, Speed [k] = end detection equivalent relative velocity, k.
= 0 to Nt, where Nt = maximum number of detected targets).
Next, in step 1604, the target existence flag [i]
Is set, and if it is set, in step 1605, the distance is calculated from the sampling timing (→ Dist [k]).
Further, in step 1606, the relative speed is calculated from the peak frequency (→ Speed [k], refer to Expression 2). In step 1607, the target number k is incremented, and the process proceeds to step 1608. Target present flag
If [i] is not set, step 1608
In step 1609, it is checked whether or not the above processing has been performed at all sampling timings. If not, the flow returns to step 1602 to perform the above processing. When the above processing is completed at all sampling timings, the distance / relative speed calculation processing is completed.

In FIG. 13, when calculating the distance, the distance is calculated only from the sampling timing when the target existence flag [i] is set.
The distance may be obtained from the ratio of the peak level of the same frequency obtained at the sampling timing when [i] is set and the next sampling timing.

Embodiment 2. The present embodiment is a modification of the processing in the CPU 5 according to the first embodiment.
As shown in FIG. 14, except that the vehicle speed detecting means 1712 and the unnecessary signal removing means 1713 are included in the CPU 5,
It is similar to the first embodiment.

FIG. 15 shows a processing flowchart of the CPU 5 in the present embodiment. Steps 1801 to 1810 are the same as steps 801 to 810 of FIG. 5 in the first embodiment.

The following is a process different from that of the first embodiment.
The vehicle speed detection process (step 1811) and the unnecessary signal removal process (step 1812) will be described.

In the vehicle speed detection process (step 1811),
The vehicle speed is calculated from the input vehicle speed pulse.

In the unnecessary signal removing process (step 1812), it is determined that the target having a relative speed corresponding to the vehicle speed is a road or a roadside stop obstacle, and it is removed as an unnecessary signal from the detection target.

FIG. 16 shows a flowchart of the unnecessary signal removing process. First, in step 1901, the target number is initialized. Next, in step 1902, it is determined whether the relative speed value Speed [k] obtained in the distance / relative speed calculation processing (step 1810) is an undetected equivalent value. move on. If it is the undetected equivalent value, the process proceeds to step 1905. In step 1903, it is determined whether the relative speed value Speed [k] is within the vehicle speed ± α, and if it is within the vehicle speed ± α, the distance value Dist is determined in step 1904.
[k] and the relative speed value Speed [k] are substituted with undetected equivalent values to make them unnecessary signals. In step 1905, the target number is incremented, and if the target number is smaller than the maximum target number, the process returns to step 1902,
The above processing is performed. If the target number is greater than or equal to the maximum target number, the unnecessary signal removal processing ends.

As described above, according to the second embodiment, unnecessary signals can be removed by determining that a target having a relative speed similar to the own vehicle speed is a stationary object such as a road.

[0047]

As described above, according to the present invention, the change in the signal magnitude at each sampling timing caused by the phase difference between the leak signal component and the reflected signal component is detected by the FFT process and the peak calculation. By doing so, the distance to the peripheral target and the relative speed are calculated, so even if there is a so-called leak signal component, such as a leak signal between transmission and reception or a reflection signal from a target fixed to the radar such as a radome, The target can be detected correctly.

Further, even when a plurality of targets are present at the same distance, the plurality of targets can be correctly detected because they are correctly discriminated due to the difference in relative speed.

Further, since the distance is calculated from the ratio of the peak timing of the same frequency in the sampling timing at which the target newly exists and the next sampling timing, the distance accuracy can be improved even with a rough sampling interval.

Further, since a wide range of transmission pulses can be used, the occupied bandwidth can be narrowed, and it can be used within the range of the current Radio Law.

Further, since the relative speed can be measured, the degree of danger can be judged according to the speed, and the control application range in the system can be expanded, such as sounding an alarm matching the driver's feeling.

Furthermore, by adjusting the ground level in accordance with the magnitude of the received signal as a whole, the threshold value for binarization is automatically set to an appropriate place, so that the mounting state is different and leakage occurs. Even if the signal components are different,
It can be used without any special adjustment or modification to the radar.

Further, it is possible to remove unnecessary signals by determining that the target having a relative speed similar to the own vehicle speed is a stationary object such as a road.

[Brief description of drawings]

FIG. 1 is a block diagram showing a pulse radar device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing waveforms of transmitted / received waves according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of the RF module according to the first embodiment.

FIG. 4 is a block diagram (a) and a time chart (b) showing the configuration of the FPGA according to the first embodiment.

FIG. 5 is a flowchart showing the processing of the CPU according to the first embodiment.

FIG. 6 is a waveform diagram illustrating the operation of changing the ground level according to the first embodiment.

FIG. 7 is a flowchart showing the processing of the ground level control means of the first embodiment.

FIG. 8 is a waveform diagram showing a reflected wave of the moving target according to the first embodiment.

FIG. 9 is a waveform diagram illustrating FFT calculation processing according to the first embodiment.

FIG. 10 is a flowchart showing FFT calculation processing according to the first embodiment.

FIG. 11 is a diagram illustrating target discrimination processing according to the first embodiment.

FIG. 12 is a flowchart showing target discrimination processing according to the first embodiment.

FIG. 13 is a flowchart showing distance / relative velocity calculation processing according to the first embodiment.

FIG. 14 is a block diagram showing a pulse radar device according to a second embodiment of the present invention.

FIG. 15 is a flowchart showing processing of the CPU according to the second embodiment.

FIG. 16 is a flowchart showing an unnecessary signal removing process according to the second embodiment.

FIG. 17 is a block diagram showing a conventional pulse radar device.

FIG. 18 is a diagram showing waveforms of transmitted / received waves of a conventional pulse radar device.

[Explanation of symbols]

1 RF module, 2 adder circuit, 3
Comparator circuit, 4 FPGA, 5 C
PU, 11 timing control circuit,
12 shift register, K1 to Kn adder, R1
~ Rn integration register, 501 transmission means,
502 receiving means, 503 comparator means, 504 received signal integrating means, 505 F
FT calculation means, 506 detection determination means, 50
7 target discrimination means, 508 distance / relative speed calculation means, 509 timing control means, 601 oscillator,
602 power distributor, 603 mixer, 604 oscillator, 605 modulator, 606 multiplier, 607 filter, 608 transmitting antenna, 609 receiving antenna, 610 RF amplifier, 611
Mixer, 612 IF amplifier, 613
Filter, 614 Amplifier, 615
Detector, 1712 Vehicle speed detecting means, 17
13 Unwanted signal removing means.

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Claims (14)

[Claims] 1. Transmitting means for transmitting pulsed radio waves,
The receiving means that receives the reflected wave in which the radio wave transmitted from this transmitting means is reflected by multiple targets and outputs the beat signal, the sampling means that samples the beat signal at a predetermined time interval from the transmission, and the sampling result FFT calculation means for performing FFT calculation at each sampling timing, detection determination means for determining the presence or absence of a target based on the output from this FFT calculation means, and distance / relative speed calculation means for calculating the distance and relative speed to the target. And a timing control means for controlling the timing of transmission, reception, and signal processing of radio waves. 2. Transmission means for transmitting pulsed radio waves,
The receiving means for receiving the reflected wave in which the radio wave transmitted from the transmitting means is reflected by a plurality of targets and outputting the beat signal, the sampling means for sampling the beat signal at a predetermined time interval from the transmission, and the sampling result The FFT calculation means for performing FFT calculation at each sampling timing, the detection determination means for determining the presence or absence of the target based on the output from this FFT calculation means, the discrimination means for discriminating the target, and the distance and relative speed to the target Distance and relative speed calculation means to calculate, transmission of radio waves,
A pulse radar device, comprising: a timing control means for performing timing control of reception and signal processing. 3. Transmitting means for transmitting pulsed radio waves,
The receiving means that receives the reflected wave in which the radio wave transmitted from this transmitting means is reflected by multiple targets and outputs the beat signal, the sampling means that samples the beat signal at a predetermined time interval from the transmission, and the sampling result The FFT calculation means for performing FFT calculation at each sampling timing, the detection determination means for determining the presence or absence of the target based on the output from this FFT calculation means, the discrimination means for discriminating the target, and the distance and relative speed to the target A distance / relative speed calculation means for calculating, a timing control means for controlling transmission / reception of radio waves, signal processing timing, and a vehicle speed detection means for detecting the speed of the own vehicle,
A pulse radar device comprising: an unnecessary signal removing means for removing an unnecessary signal such as a road. 4. The discriminating means for discriminating a target comprises:
The pulse radar device according to claim 2, wherein the target is discriminated using a peak frequency obtained from the FFT calculation means. 5. When the discriminating means discriminates the targets in order from the sampling timing corresponding to the short distance, when the peak frequency of the detected target is the first detected frequency, the distance from the sampling timing to the target is obtained. 5. The pulse radar device according to claim 4, further comprising a distance / relative velocity calculating means for obtaining a relative velocity with respect to the target from the frequency. 6. When the discriminating means discriminates the targets sequentially from the sampling timing corresponding to the short distance, when the peak frequency of the detected target is the first detected frequency, the sampling timing and the next sampling point are obtained. 5. The pulse radar device according to claim 4, further comprising a distance / relative velocity calculating means for obtaining a distance to the target from the ratio of the peak levels of the same frequency and obtaining a relative velocity with the target from the frequency. . 7. Transmitting means for transmitting pulsed radio waves,
A comparator for receiving a reflected wave in which the radio wave transmitted from the transmitting means is reflected by a plurality of targets and outputting a beat signal, and binarizing the signal from the receiving means by a preset predetermined level. Means and
Received signal integrating means for sampling the output of the comparator means at a predetermined time interval from transmission, and integrating the sampling result a predetermined number of times at each sampling timing, and the integrated result of the received signal integrating means at each sampling timing for a predetermined time. FFT calculation means for reading out each time and performing FFT calculation, detection determination means for judging the presence or absence of a target based on the output from this FFT calculation means, and distance / relative speed for calculating the distance and relative speed to the target A pulse radar device comprising: an arithmetic means and a timing control means for controlling the timing of transmission, reception, and signal processing of radio waves. 8. Transmission means for transmitting pulsed radio waves,
A comparator for receiving a reflected wave in which the radio wave transmitted from the transmitting means is reflected by a plurality of targets and outputting a beat signal, and binarizing the signal from the receiving means by a preset predetermined level. Means and
Received signal integrating means for sampling the output of the comparator means at a predetermined time interval from transmission, and integrating the sampling result a predetermined number of times at each sampling timing, and a predetermined result for integrating the received signal integrating means at each sampling timing. FFT calculation means for reading out at each time and performing FFT calculation, detection judgment means for judging the presence or absence of a target based on the output from this FFT calculation means, discrimination means for discriminating the target, distance to the target, and A pulse radar device comprising: a distance / relative speed calculation means for calculating a relative speed; and a timing control means for performing timing control of transmission, reception, and signal processing of radio waves. 9. Transmission means for transmitting pulsed radio waves,
A comparator for receiving a reflected wave in which the radio wave transmitted from the transmitting means is reflected by a plurality of targets and outputting a beat signal, and binarizing the signal from the receiving means by a preset predetermined level. Means and
Received signal integrating means for sampling the output of the comparator means at a predetermined time interval from transmission, and integrating the sampling result a predetermined number of times at each sampling timing, and a predetermined result for integrating the received signal integrating means at each sampling timing. FFT calculation means for reading out at each time and performing FFT calculation, detection judgment means for judging the presence or absence of a target based on the output from this FFT calculation means, discrimination means for discriminating the target, distance to the target, and Distance / relative speed calculation means for calculating relative speed, timing control means for timing control of transmission / reception of radio waves, signal processing, vehicle speed detection means for detecting the speed of the own vehicle, unnecessary signals such as roads, etc. A pulse radar device comprising: an unnecessary signal removing unit for removing the unnecessary signal. 10. The pulse radar device according to claim 8, wherein the discriminating means for discriminating the target discriminates the target by using a peak frequency obtained from the FFT calculating means. 11. When the discrimination means discriminates targets in order from a sampling timing corresponding to a short distance,
When the peak frequency of the detected target is the first detected frequency, it is characterized by having a distance / relative speed calculation means for calculating the distance to the target from the sampling timing and for calculating the relative speed with the target from the frequency. The pulse radar device according to claim 10. 12. When the discriminating means discriminates targets in order from a sampling timing corresponding to a short distance,
When the peak frequency of the detected target is the frequency that is detected for the first time, the distance to the target is calculated from the ratio of the sampling timing and the peak level of the same frequency obtained at the next sampling point. 11. The pulse radar device according to claim 10, further comprising a distance / relative velocity calculation means for obtaining a relative velocity. 13. A ground level changing means for changing the ground level of a received signal according to the result of integration by the received signal integrating means, according to any one of claims 7 to 12. The pulse radar device described. 14. The ground level changing means is controlled by a ground level control means for outputting a signal when an average value of integration results of sampling timings by the reception signal integrating means exceeds a predetermined range. 14. The pulse radar device according to claim 13.