JPH02212791A - Fm-cw radar - Google Patents

Abstract

PURPOSE:To make radar performance most properly set according to a use condition by respectively varying distance resolution, a maximum measurement distance and a spectrum analysis processing time. CONSTITUTION:When in a radar an arithmetic control circuit 14 takes in data of wave detection signals from an A-D converter 13 in order whenever receiving band width R is changed and data groups of spectrum analysis is obtained, data taken-in number is varied in the arithmetic control circuit 14. Since in the arithmetic circuit 14 the taking-in of the data is repeating operation, the number of the time at which a series of orders for taking in the data on a program is repeated is counted, and the taking-in of the data is finished when it reaches n-times. Accordingly, if n-times at the time when a series of the orders in which the data in the arithmetic control circuit 14 are taken in are set arbitrarily, data taken-in number of the wave detection signals can be varied.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an ir h, iC
The present invention relates to a Vi' radar device.

Recently, FM-CW radar devices have been installed on moving vehicles such as automobiles and heavy vehicles to measure the distance and relative speed between them and other automobiles or obstacles. Alert the driver if you enter! Automatically turn off! We are currently developing a system to prevent collisions by making the robot work harder.

The operating principle of the ii'' M-c W radar device is as follows.

As shown in 2R in Fig. 2, the signal with the fundamental frequency fo is
l '11' Curved 1. to o+Δf at m. Go-1
, and then linearly descending to fo (f m = 1. / T m is the modulation frequency, Δf is the frequency deviation width), and the frequency-modulated signal is transmitted as the transmission wave T w -(l/-da) is emitted toward the monitoring area, and the reflected wave R from the target existing in that area is
Receive w. .

When comparing the received (A wave rw) with the previous transmitted waves R, il on the same time axis, the phase shifts according to the round trip time td of the radio wave, and the frequency difference at that time is ``I is ¥J1!? The distance to the target is determined by measuring the frequency difference f+, which is proportional to the distance to the target.
"ing.

Furthermore, by determining t1 and determining the temporal change d x /dt in the distance (x) between the target and r, the relative velocity can be determined. In the de~i-CW l,-da device,
The frequency difference between the transmitted and received signals obtained by mixing the transmitted signal and the received ∆ signal is the frequency of the signal that crosses one tine, 11, developed by the same applicant) (see Japanese Patent Application Laid-Open No. 1983/1!01873) The conventional FM-CW radar system using the spectral distribution formula, such as the 5-lever system, has a maximum distance resolution of 11i! when determining the distance between targets.
11 Fixed distance, spectrum analysis processing time, and performance are fixed.

In this regard, when an FM-CW meter device is mounted on a car, etc., and the vehicle is controlled while measuring the distance to the vehicle in front or an obstacle in front, the speed of the vehicle Distance resolution adapted to various situations such as road congestion, up to 41 meters, fixed distance of 5 subb [Hellum analysis processing time] You can determine the distance to the target with the letter performance, and A1 is more @It will be possible to perform appropriate vehicle travel control using fT.

Purpose The present invention has been made with the following points in mind.
F based on the Subek 1-Ra 11 analytical formula, which makes it possible to set the radar performance optimally according to the usage situation by making the constant distance and spectrum analysis processing times variable.
The present invention provides an M-CW radar device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

Figure 1 shows the Subek 1-ram analysis formula according to the present invention.
This shows an example of the basic configuration of an M-CW radar device.
FM that obtains signals based on the frequency difference between transmitted and received signals
- cw radar main body A and its wide transmission and reception (the frequency difference between the n pieces) The frequency of the signal is 8111 by the principle of \terodyne frequency measurement, and the high vector t-:) lz analysis 4, F M-(': W
As for the radar main body A, the +7i1 wave number' modulation section l is used to generate either a signal of 1 in the oscillator 3, a signal with a fixed wave number of L [0], or modulation (modulation (d
1j, - its oscillator'
3, the frequency modulated signal is distributed by the power divider 4, with most of the output going to the circulator 5, and some of it going to the mixer 6, respectively.
It's starting to look like this.

In the circulator 5, lj, Elasai L t= (J 饥は〉Thena AN T i,: led 1), and the free space 1
．． This radio wave 1λ2L7 is emitted 1.1, and the reflected wave from the target O is received by the antenna ANT, and the received signal is given to the mixer 6 through the circulator 5, where it is mixed with the transmitted signal. The output signal of the mixer 6 is amplified by a preamplifier 7, and a signal having a receiving frequency fr according to the frequency difference between the transmitted and received signals is obtained from the preamplifier 7.

Also, as Ube B at distance t1, receive A, 7l-i- of 1 frequency fr; 'do local oscillation 4f! The signal at the local oscillation frequency fv from 'a:4+6' is mixed in the mixer 8, and the signal at the frequency fd coming out from the mixer 8 is applied to the bandpass filter 10 through the amplifier 9, where the signal in the intermediate frequency band is mixed. Only the frequency signal is filtered.Then, the signal that has passed through the bandpass filter IO is sent to the amplifier 11.
The voltage signal is detected by a converter 13, which converts the digital data into IJ, which is composed of a microcoater or a micro combicoater. The data is read into the arithmetic control circuit 14 and stored in the internal memory.

In such a device, the frequency ft (of the signal output from the mixer 8 is determined by the difference (or sum) of the reception frequency f+ and the local oscillation frequency fv, fr-
fv=fd (also 1 t' v-f +f d, f
The following relationship holds: r+f v=f d,).

Therefore, the control signal output from the arithmetic control circuit 1.1 passes through the D/A converter 15 to the local oscillator 1.
1; By changing the local oscillation frequencies 1 to 1 at t9, the signal frequency fd output from the mixer 8 can be variably controlled. Master under the control of 14? Then, the local oscillation frequency f of the local oscillator 1 [5] is made variable. .

As shown in FIG. 3, the receiving band W, which is determined by the passband width of the bandpass filter 10, is shifted from the low frequency range to the high frequency range by the width of 4':i. The voltage detected by the wave detector 1:2 is converted into digital data by the A/I) converter) and -),
Then, a data group is obtained by sequentially storing it in the internal memory of the arithmetic control circuit 11 and performing the Ram analysis.

However, the arithmetic and control circuit 14 does not cover the reception band W within a predetermined range. Each data is stored in an internal memo, and then finally 0)ノ,BE,/l=crumb cloth information 1 ri11
7] Detection 'city pressure or bar (1) Detection is performed although it is in the novel state (1), and as shown in Fig. The one who is in state 5. (
(or multiple), the corresponding local oscillation frequency fX is determined from the data number of the receiving frequency fr that is in the resonant state at that time, and the frequency of the received frequency fr that is in the resonant state at that time is calculated. The distance between the target objects is calculated.

Or, the arithmetic control circuit 1.1 is!・-tE to the device
Let Lm be the maximum measurement distance of the target object that can be detected, and let r'l be the number of data in the data group analyzed and h. Knowing Nx, the distance to the target, χ, is expressed as follows,
4, L x = N x 1 I-m /
nCurrently, FM using such a spectrum analysis formula
-Distance resolution when determining the distance to the target object in CW radar equipment, maximum a+++ fixed distance, subek 1-
RAM analysis processing time (reception,: scanning of band W 1'Si:i
l) -) and consider each of them, the result is as follows: 1, the propagation velocity of the radio wave is 1^j when modulating the C5 frequency, Δf is the wave number deviation width, f is the modulation frequency, and L is the maximum measurement distance.
Il+, frllI is the reception frequency output from mixer 7 when the target is at the maximum measurement distance, fw is the frequency resolution of spectrum analysis (frequency width of reception band W), Svek 1 - Lai analysis 5 - Ito If the number of data in the group is [l, and the distance resolution is Qd, then the following formula is established. , frm;
4 Lm-fm・Δ1'/c -(+)frlIl
=n 1fw −(2)Qd=
LIll/n ・-(3)(1)
, (2), From equation (3), Dd=c-fh/4f
+I+・8f(4) is obtained.

So, from equation (11), if we change the frequency resolution f b□, the modulation frequency (m, and the frequency deviation width Δf), we can make the distance resolution Qd variable. Also, from equations (1) and (2), I+n+=n-f-r:/4f+n-Δf...(5)
is obtained.

Therefore, from equation (5), if you change the spectrum 1 - ram analysis frequency resolution fw, modulation frequency fm, frequency deviation width Δf2 spec 1 - the number of data 11 of the ram analysis data group, the maximum is 1! The constant distance LIll can be made variable.

Further, when the scanning time in the H band W during spectrum analysis is ta, the following equation holds true.

ta=n/fv-(6)(1),
(2'l, from formula (6), ta=4 L+o・f+n・Δf/c−fw' −
(7) is obtained.

Therefore, from equation (7), the subek1-ram analysis frequency resolution ft1, the modulation frequency fIn, and the frequency deviation width Δ
By changing f, the maximum measurement distance L In, the spectrum rough 1 minute + and f1 processing time T can be made variable.
The present invention utilizes a spectrum analysis type I.M.C.
Distance resolution and maximum measurement distance of the W rate device are excellent! γi for each special/hi1 between ~ Lamb analysis processing +1i']
jJ% of the analysis frequency resolution [V, modulation frequency f m, frequency deviation width △f: 3te]
;4'+ '7) −'l any l] element,
Or 2-] Hereinafter, each element in 1 is made variable 1, or the number of data 1'l of the spectrum analysis formula group is made variable. 1
, Hereinafter, we will explain the 14 examples in which the Svek1-Ram analysis frequency resolution f %l, the modulation frequency f +++, the frequency deviation width Af, and the number of data of the Svetsuno1-Ra11 analysis theta group ■1 are changed, respectively. .

In order to change the spectral IN analysis frequency resolution fW, the present invention slightly changes the pass*W2 width in the bandpass filter 10 in the configuration shown in FIG.

Collectively, as shown in FIG. 4), ((', -band filter 10 includes a plurality of band filters 101, 1.02 with the same center frequency and different passband widths, respectively).
', 1011 are provided in parallel, and the bandpass filter 10x has an appropriate pass band width by switching the switch SW.
(x = 1., 2. ., +1) 1. The switch SW is switched, for example, in response to a distance resolution selection command input from an operation unit (not shown) or by an arithmetic control circuit. The arithmetic control circuit 1 operates according to the control contents programmed in advance from the vehicle running speed read from 14.
4, control 1;

In addition, in order to change the modulation frequency fm, in the present invention, 5
As shown in FIG. 5, frequency data fo, fl, f3, . . . . reads out frequency data sequentially from the memory where 42 times have been recorded in advance, converts the read frequency data into an analog voltage signal by performing I/A conversion, and then applies the analog voltage signal to a low-pass filter. This means that a triangular wave modulation signal of 11 J is generated by passing the frequency data through the memory, and the read cycle is changed when frequency data is read from the memory. , 6th
The figure shows an example of a 74-dimensional configuration of the modulation (Fi signal generation circuit 2) in the configuration of FIG.

-t configuration, a predetermined timing signal is generated from the timing 4tE signal generation circuit 22 based on the clock signal generated from the clock circuit 21, and the timing signal is sent to the address counter 23 Li2. The frequency data is sequentially outputted from the ROM 24 by 1 to'JL according to the value of the counter output. , then 5,
The read frequency data is sent to the launch circuit 25 from the timing signal generation circuit 22 at timing 4g.
The latched frequency data is sequentially latched according to the signal, and the latched frequency data is sequentially given to the 1) A converter 2613. [1
)・Since the city pressure signal output from the A converter 26 changes stepwise over time, its analog voltage (No. The changes are made so that the intervals between each stage in the analog voltage signal that changes in 9 stages are almost linear.

In such a modulation signal generation circuit 2, in the present invention,
The clock circuit 21 has a frequency fc as shown in FIG.
Tarock oscillator (crystal oscillator) that generates a clock signal
211, and a frequency divider 212 that divides the clock frequency fc into 1/N and allows the setting of the N value to be changed. In response to a distance resolution selection command input from the operation unit, or the arithmetic control circuit 1
Control data DATA is sent from the arithmetic control circuit 14 to the frequency divider 212 to determine the frequency division value N according to the control content plotted from the vehicle running speed read by 4.
1 is given so that the frequency division value N in the frequency divider 212 is set to a predetermined value.

Therefore, the frequency division value N in the frequency divider 212 is
By changing the IE, the readout cycle when reading frequency data from the ROM 24 is variably controlled.
12, thereby allowing the modulation frequency f m to be changed arbitrarily.

Moreover, in order to change the one frequency deviation width Δf, in the present invention, as shown in FIG.
11 was equally divided into the same numbers along the time axis. Frequency data fO, fl, f3. reads the frequency data sequentially from the registered memo 1 L2,
The read out frequency data is 1) A-converted into an analog voltage signal, and then the analog voltage signal is passed through a low-pass filter to re-Zt the triangular wave modulation signal. When reading out the frequency range from the memory, the address range for reading is changed.

11 Specifically, in the modulation signal generation circuit 2 shown in FIG. 6, the atto L/counter 2:3 is as shown in FIG.
A counter 231 that counts the input tally clock CK (in this case, a timing signal that is output from the timing signal generation circuit 22 and outputs 1), and its counter! - Reset the counter 231 when the value reaches the set value 1 ~ Signal RESET
is made into an N-adic link configuration such that Ij, Er-Number output circuit 23:2, and the set value in the -Number output circuit 232 can be made variable under the control of the arithmetic control circuit 14. 5. For example, the calculation is performed in response to a distance resolution selection command input from an operation unit (not shown), or in accordance with the control content plotted from the vehicle travel speed read by the calculation control circuit 14. From the control circuit 14 to the coincidence detection circuit 2
32 is given N-ary control data DATA, 2, A1, and the N-adic counter I~ value in the minus number circuit 232 is set to a predetermined value.

In addition, in order to change the data number r1 of the spectra 11 analysis data group, in the present invention, in the configuration shown in FIG.
- When the data of the detection signal is sequentially taken in from the D converter 13 to obtain a data group for spectrum analysis, the arithmetic control circuit 14.1. : The number of pigs taken in is made variable.

In the arithmetic control circuit 14, the acquisition of the data of the detection signal is a repetitive operation, so the number of times to repeat the series of commands to acquire the data is expressed as 1-1 in the program.
Then, when the number of times reaches 11, the acquisition of that Te 0-Even is finished.

Therefore, if the number of times 11 for repeating a series of commands to capture data that is input to the arithmetic control circuit 14 is arbitrarily set by manual operation from an operation unit (not shown), the number of times the data of the detected signal is captured can be increased. It can be made variable. .

1. In the FM-CW radar device according to the present invention, when a frequency measurement method based on spectrum 1-ram analysis is adopted, the frequency resolution of spectrum 1-ram analysis.

A stage for varying the number of data in the spectrum analysis data group by changing the means for varying at least one of the three elements of the frequency of the modulation signal and the frequency shift of the modulation signal. By taking the distance resolution, maximum measurement distance, and subek1 when determining the distance to the target,
- The RAM analysis processing time can be arbitrarily varied7, thereby adapting to the usage conditions such as the traveling speed of the vehicle equipped with the FM-CW radar WtW, and also making it possible to determine the distance between targets etc. using the radar performance. It has this excellent advantage.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a basic configuration example of the FM-CW radar device II according to the present invention, and FIG.
Characteristic diagram of transmitted and received signals at J'7 in the W radar device, Part 3
The figure is a characteristic diagram showing the detection voltage of the reception frequency proportional to the distance to the target in the Flvl-CW radar device and the reception band by Svek 1 Helam analysis, and Fig. 4 is the characteristic diagram of the FM-CW radar device according to the present invention. A block diagram showing an example of the JL type configuration of the bandpass filter part in FIG. 5 is a characteristic diagram showing the frequency at each division point when the triangular wave modulated signal is equally divided in the time axis direction, and FIG. 7 is a block diagram showing a specific configuration example of a modulation signal generation circuit in an FM-CW radar device according to the present invention, and FIG.
Block diagram showing an example of the configuration of the cross circuit in No. 3, No. 8
The figure is a block diagram showing an example of the configuration of the A1 head counter in the modulation (II\) generation circuit of the I・' M-c W rate device 1' according to the present invention. Circuit:) Oscillator 4 Power distributor 5 Surgico 1...-Taro, 8 Mixer 7 ・111f position amplifier 9, 11 Amplifier 1
0. 101-1. On-band filter: 2 Detector 13/A-) converter 1/1 Arithmetic control circuit
+5-D-A converter 1 (3 local oscillators 21...Clock circuit: 2:2 ・Timing key, (ji oscillator 1 circuit)
2:3・71-res counter 24- ROM:'25
Latch circuit, 16-1')・A converter, 270-
hess filter

Claims (1)

[Claims] 1. The frequency between the transmitted and received signals obtained by mixing a transmitted signal obtained by frequency-modulating a fundamental frequency signal according to a modulation signal and a received signal resulting from a reflected wave from a target object. In an FM-CW radar device in which the frequency of a signal according to the difference is determined by spectrum analysis,
An FM-CW radar device characterized in that it takes means for making frequency resolution of spectrum analysis variable. 2. A signal that follows the frequency difference between the transmitted and received signals obtained by mixing the transmitted signal and the received signal is mixed with a local oscillation frequency signal whose frequency is made variable in a mixer, and the output signal of the mixer is The local oscillation frequency corresponding to when the peak of the detected signal is obtained is determined from the data group of the detected signal obtained by passing it through a bandpass filter and then detecting it. According to the above item 1, characterized in that a spectrum analysis means is used to determine the frequency of a signal according to a frequency difference, and the frequency resolution of the spectrum analysis is made variable by changing the passband width of the bandpass filter. FM-CW radar device. 3. The frequency of the signal is determined according to the frequency difference between the transmitted and received signals obtained by mixing the transmitted signal, which is a fundamental frequency signal frequency-modulated according to the modulation signal, and the received signal due to the reflected wave from the target object. 1. An FM-CW radar device that obtains information by spectrum analysis, characterized in that it takes means to vary the frequency of a modulated signal. 4. When the modulated signal is equally divided in the time axis direction, the frequency data at each division point is sequentially read from the memory in which it is registered in advance, and the read frequency data is sequentially D/A converted and then low-pass According to item 3 above, the method is characterized in that the modulated signal is reproduced by passing it through a filter, and the frequency of the modulated signal is made variable by changing the reading period of the frequency data from the memory. FM-CW radar device. 5. Item 4 above, characterized in that the period of reading the frequency data from the memory is changed by varying the period of the clock signal given to the address counter that sequentially reads the frequency data from the memory using a frequency divider. FM-CW radar device according to the description. 6. The frequency of the signal is determined according to the frequency difference between the transmitted and received signals obtained by mixing the transmitted signal obtained by frequency modulating the fundamental frequency signal according to the modulation signal and the received signal due to the reflected wave from the target object. What is claimed is: 1. An FM-CW radar device that obtains information by spectrum analysis, the FM-CW radar device being characterized in that the frequency shift width of a modulated signal is made variable. 7. When the modulated signal is equally divided in the time axis direction, the frequency data at each division point is sequentially read from the memory in which it is registered in advance, and the read frequency data is sequentially D/A converted and then low-pass The modulated signal is reproduced by passing it through a filter, and the frequency shift width of the modulated signal is made variable by changing the address range for reading frequency data from the memory. FM- according to the description in Section 5
CW radar equipment. 8. Using an N-ary counter as an address counter that sequentially reads frequency data from memory according to a clock signal,
The F according to item 7 above, characterized in that the address range for reading frequency data from the memory is changed by making the N-ary set value of the counter variable.
M-CW radar device. 9. The frequency of the signal is determined according to the frequency difference between the transmitted and received signals obtained by mixing the transmitted signal obtained by frequency modulating the fundamental frequency signal according to the modulation signal and the received signal due to the reflected wave from the target object. 1. An FM-CW radar device that obtains data by spectrum analysis, characterized in that it takes means for making the number of data in a spectrum analysis data group variable. 10. A signal according to the frequency difference between the transmitted and received signals obtained by mixing the transmitted signal and the received signal is mixed with a local oscillation frequency signal whose frequency is made variable in a mixer, and the output signal of the mixer is The local oscillation frequency corresponding to when the peak of the detected signal is obtained is determined from the data group of the detected signal obtained by passing it through a bandpass filter and then detecting it. Item 9 above, characterized in that the spectrum analysis means for determining the frequency of the signal according to the frequency difference is used, and the number of data acquired when determining the peak of the detected signal from the data group of the detected signal is made variable. FM-CW by
radar equipment.