JP2000075021A - Target information detecting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain information in addition to the distance and relative speed of a target by providing an FM-CW radar comprising an oscillator, a power distributing means, an antenna, a frequency converter, a distance and relative speed detecting circuit, and a code detecting circuit. SOLUTION: A first antenna 8a delivers a transmission signal toward a target 13 with a radio wave reflector where the reflection amount of high frequency modulation signal is time variant depending on code information. A second antenna 8b receives a reflection signal from a target 13 with a radio wave reflector and delivers a receiving signal. A frequency converter 9 receives a receiving signal and a local oscillation signal and delivers a video signal having sum and difference frequency of both signals. A distance and relative speed detecting circuit 10 analyzes the video signal subjected to Fourier transform on the frequency axis and detects information on the distance and relative speed of the target 13 with a radio wave reflector, and the like. A code detecting circuit 12 analyzes the video signal on the time axis, compares the level of the video signal with a threshold level and encodes the video signal thus detecting the code information on the target 13 with a radio wave reflector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detection of target information mounted on a moving body such as an automobile and detecting a target such as a person, a vehicle, and an obstacle around the mounted moving body using radio waves. It is about the system.

[0002]

2. Description of the Related Art FIG. 6 shows an example of a use state of a target information detection system when an FM-CW radar is mounted in front of a vehicle. In the figure, 1 is a road, 2a and 2b are roads 1
, A vehicle passing in the direction of a, 3 is a following vehicle 2b of the vehicle 2a
FM-CW radar for monitoring the front mounted on the vehicle, 4 is an obstacle such as a telephone pole installed on the roadside of the road 1 or a parked vehicle parked on the roadside, 5 is a person passing or crossing the road 1 It is.

[0003] Next, the use situation will be described. Road 1
Is mounted on the vehicle 2b passing in the direction of a.
The CW radar 3 radiates forward a frequency-modulated transmission radio wave, receives reflected waves from a vehicle 2a, an obstacle 4 and a person 5 traveling ahead, and receives the reflected waves, the intensity thereof, the frequency shift by Doppler, and the radio waves. Is detected, and the distance and the relative speed to the vehicle 2a are obtained from the result, and are used for safety measures such as a warning for collision prevention or brake control.

[0004] Regarding the use situation of such a system, for example, see IEICE Technical Report MW94-48 (1994-0).
9) It is described in "Development of millimeter-wave application system in Japan" and "All of ITS" by Nihon Keizai Shimbun (P62-67).

FIG. 7 is a block diagram showing the configuration of a conventional target information detection system 3 mounted on the vehicle 2b in FIG. 6, wherein 6 is an oscillator, 7 is power distribution means, 8a and 8
b is the first and second antennas, 9 is the frequency converter, 10
Is a distance and relative speed detection circuit, and 11 is a target.

Next, the operation will be described. In FIG. 7, an oscillator 6 includes a high-frequency modulated signal (of FRF ± ΔF)
FRF is the center frequency, and ΔF is the modulation frequency width). The power distribution unit 7 converts a part of the high-frequency modulated signal into a local oscillation signal and the rest as a transmission signal using the first antenna 8a.
Output to The first antenna 8a outputs a transmission signal toward the target 11. The second antenna 8b receives a reflected signal from the target and outputs a received signal. The frequency converter 9 receives the received signal and the local oscillation signal and outputs a video signal having a sum and a difference between the two frequencies. The distance and relative speed detection circuit 10 performs a Fourier transform on the video signal, analyzes the video signal on a frequency axis, and detects information such as a distance to the target and a relative speed.

Next, the operation will be supplementarily described. FIG. 8 shows an operation principle diagram of a conventional FM-CW radar. FIG. 8 (a)
Is a transmission signal and a local oscillation signal (frequency FRF ± ΔF
Is the center frequency, ΔF is the modulation frequency width, and the curve b is the received signal. In the case of the FM-CW radar, a frequency-modulated transmission signal is irradiated on a target, and the reception signal has a delay time twice as long as the distance to the target,
The received signal is frequency-converted (homodyne detected) by the local oscillation signal, and becomes a video signal having a beat frequency component Fb corresponding to the target distance / speed as shown by a curve c in FIG. 8B. Next, the distance and relative speed detection circuit 10 calculates the distance to the target and the relative speed from the frequency Fb. Here, for simplification of the description, a case where the own speed and the target speed are the same, that is, a case where the relative speed = 0 is shown.

[0008]

In the apparatus constructed as described above, information on the distance and relative speed of the target can be obtained, but other information such as the type of the target cannot be obtained. There were challenges.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain new information other than the distance and relative speed of a target.

[0010]

According to a first aspect of the present invention, there is provided a target information detecting system in which a part or the whole of a target is FM-
A target whose polarization of the reflected wave of the high-frequency modulation signal transmitted from the CW radar changes with time according to the code information; and an oscillator, a power distribution unit, first and second antennas, a frequency converter, and a target. The FM-CW radar comprises a distance and relative speed detection circuit for detecting distance and relative speed, and a code detection circuit for obtaining code information of a target.

Further, the target information detection system according to the second aspect of the present invention is a variable polarization system that changes the polarization of the reflected wave of the high-frequency modulation signal transmitted from the FM-CW radar with a control signal. A target with a radio wave reflector, a control unit for controlling the polarization of the reflected wave of the target with a variable polarization radio wave reflector, an oscillator, power distribution means, first and second antennas, a frequency converter, and a target And an FM-CW radar comprising a distance and relative speed detection circuit for detecting the distance and relative speed of the target, and a code detection circuit for obtaining code information of the target.

A target information detection system according to a third invention uses a circulator for separating a transmission signal and a reception signal in either the target information detection system according to the first invention or the target information detection system according to the second invention. Thus, the first and second antennas are combined into one for transmission and reception.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing Embodiment 1 of the present invention.
3, 6 to 10 are the same as the conventional target information detection system, 12 is a code detection circuit, 13 is a radio wave reflector whose polarization of the reflected wave of the high frequency modulation signal changes with time according to the code information. It is a target. The target 13 with the radio wave reflector, in which the polarization of the reflected wave of the high-frequency modulation signal changes with time according to the code information, is obtained by partially or entirely using the FM-CW.
The reflected wave of the high-frequency modulated signal transmitted from the radar is constituted by a reflector whose polarization changes with time according to the code information.

FIG. 2 shows a high-frequency modulation signal in which, for example, a radio-wave reflector that reflects a high-frequency modulated signal with a horizontal polarization and a radio-wave reflector that reflects with a vertical polarization alternately appear on the surface of a target object with respect to a time change. FIG. 7 is a diagram showing a time change characteristic of the amount of reflection of the radio wave reflector target 13 in which the polarization of the reflected wave changes with time according to the code information. As shown in the figure, the polarization of the reflected wave of the high-frequency modulation signal changes with time.

Next, the operation will be described. In FIG. 1, an oscillator 6 includes a high-frequency modulated signal (of FRF ± ΔF)
FRF is the center frequency, and ΔF is the modulation frequency width). The power distribution unit 7 converts a part of the high-frequency modulated signal into a local oscillation signal and the rest as a transmission signal using the first antenna 8a.
Output to The first antenna 8a outputs the transmission signal to the radio wave reflector target 13 in which the polarization of the reflected wave of the high frequency modulation signal changes with time according to the code information. The target 13 with the radio wave reflector whose polarization of the reflected wave of the high-frequency modulation signal changes with time according to the code information changes the polarization of the reflection wave with time of the high-frequency modulation signal transmitted from the FM-CW radar 3. And reflect. The second antenna 8b receives a reflection signal from the radio wave reflector-attached target 13 in which the polarization of the reflected wave of the high-frequency modulation signal changes with time according to the code information, and outputs a reception signal. The frequency converter 9 receives the received signal and the local oscillation signal and outputs a video signal having a sum and a difference between the two frequencies. Distance and relative speed detection circuit 1
0 is a Fourier transform of the video signal, which is analyzed on the frequency axis, and the distance and relative speed with the radio wave reflector-attached target 13 in which the polarization of the reflected wave of the high frequency modulation signal changes with time according to the code information. Etc. are detected. The code detection circuit
A radio wave reflector in which the video signal is analyzed on a time axis, and the level of the video signal is compared with a threshold value and encoded, whereby the polarization of the reflected wave of the high frequency modulation signal changes with time according to the code information. The code information of the attached target 13 is detected.

Next, the operation will be supplementarily described. FIG. 3 shows an operation principle diagram of the conventional FM-CW radar. FIG. 3 (a)
Is a transmission signal and a local oscillation signal (frequency FRF ± ΔF
Is the center frequency, ΔF is the modulation frequency width, and the curve b is the received signal. In the case of the FM-CW radar, a frequency-modulated transmission signal is irradiated on a target, and the reception signal has a delay time twice as long as the distance to the target,
The received signal is frequency-converted (homodyne-detected) by the local oscillation signal, and becomes a video signal having a beat frequency component Fb corresponding to a target distance / speed as shown by a curve c in FIG. Next, the distance and relative speed detection circuit 10 calculates the distance to the target and the relative speed from the frequency Fb. Here, for simplification of the description, a case where the own speed and the target speed are the same, that is, a case where the relative speed = 0 is shown. In addition, since the polarization of the reflected wave of the high-frequency modulated signal changes with time in accordance with the code information, the polarization of the reflected wave from the target 13 with the radio wave reflector changes. If, the received signal level increases when the polarization of the reflected wave is horizontal, and decreases when the polarization is vertical. Therefore, the beat signal is represented by the curve d in FIG.
The level changes like. The beat signal is encoded by the chord detection circuit 12 as "0" when the beat signal is higher than the threshold value shown by the curve e in FIG. The code information of the radio wave reflector attached target 13 whose polarization of the reflected wave of the signal changes with time corresponding to the code information is detected.

In the target information detection system configured as described above, the distance and the relative speed to the target are detected, and the reflected wave of the reflected wave of the high-frequency modulated signal changes with time according to the code information. With the body target 13, it is possible to obtain code information of the target corresponding to the time change of the polarization of the reflected wave.

Embodiment 2 FIG. FIG. 4 is a block diagram showing Embodiment 2 of the present invention.
0 is the same as the conventional target information detection system,
Reference numeral 12 is the same as that described in the configuration diagram of the first embodiment, reference numeral 14 is a target with a variable polarization radio wave reflector, and reference numeral 15 is a control unit. The target 14 with a variable polarization radio wave reflector is configured to change the polarization of the reflected wave of the high frequency modulation signal transmitted from the FM-CW radar by a control signal of the control unit 15 with time. Therefore, the code information of the target can be changed, and more information can be obtained.

Embodiment 3 FIG. 5 is a block diagram showing a fourth embodiment of the present invention.
Are the same as the conventional target information detection system,
3 is the same as that described in the configuration diagram of Embodiment 1,
16 is a circulator.

Next, the operation will be described. In FIG. 5, the oscillator 6 includes a high-frequency modulated signal (of FRF ± ΔF)
FRF is the center frequency, and ΔF is the modulation frequency width). The power distribution means 7 outputs a part of the high-frequency modulated signal as a local oscillation signal and outputs the rest as a transmission signal. The circulator 16 guides the transmission signal to the antenna 8 and guides the reception signal output from the antenna 8 to the frequency converter 9. The antenna 8 outputs the transmission signal to the target 13 with a radio wave reflector in which the polarization of the reflected wave of the high-frequency modulation signal changes with time according to the code information. The target 13 with the radio wave reflector, in which the polarization of the reflected wave of the high frequency modulation signal changes with time according to the code information, converts the high frequency modulation signal transmitted from the FM-CW radar 3 into a polarization as shown in FIG. reflect. The antenna 8 receives a reflection signal from the radio wave reflector-attached target 13 in which the polarization of the reflected wave of the high-frequency modulation signal changes with time according to the code information, and outputs a reception signal. The frequency converter 9 receives the received signal and the local oscillation signal and outputs a video signal having a sum and a difference between the two frequencies. The distance and relative speed detection circuit 10 performs a Fourier transform on the video signal and analyzes on the frequency axis, and the target 13 with the radio wave reflector with the polarization of the reflected wave of the high-frequency modulated signal changes with time according to the code information. Information such as the distance and relative speed of the vehicle. The code detection circuit 12 detects the output level of the video signal on the time axis, judges the detected output level based on a set threshold value, encodes the video signal, and thereby polarizes the reflected wave of the high-frequency modulation signal. The code information of the target 13 with the radio wave reflector whose wave changes with time according to the code information is detected.

In the target information detecting system configured as described above, the distance and the relative speed to the target are detected, and the polarization of the reflected wave of the high-frequency modulation signal changes with time according to the code information. With the target 13 with a reflector, it is possible to obtain code information of the target corresponding to the time change of the polarization of the reflected wave.

Further, by sharing the antenna for transmission and reception, one antenna can be omitted, so that the size and cost of the device can be reduced.

[0023]

According to the first aspect of the present invention, the reflected wave polarization of the high-frequency modulation signal changes with time according to the code information. It becomes possible to obtain target code information corresponding to the change. As a result, in addition to the distance to the target and the relative speed,
There is an effect that the target code information can be obtained.

According to the second aspect of the present invention, the variable polarization wave reflector is controlled by the control unit and the code detection circuit which control the polarization of the reflected wave of the target with the variable polarization wave reflector and the target with the variable polarization wave reflector. It is possible to obtain the target code information corresponding to the time change of the polarization of the reflected waves of the target with the wave radio wave reflector and the target with the variable polarization radio wave reflector. As a result, there is an effect that the code information of the target can be obtained in addition to the distance and the relative speed to the target. Further, since the code information can be changed by the control unit, it is possible to obtain more target code information.

Further, according to the third invention, in either the target information detection system according to the first invention or the target information detection system according to the second invention, the antenna is shared for transmission and reception. Since it can be omitted, it is possible to obtain the target code information in addition to the distance and the relative speed to the target, and to achieve an effect of reducing the size and the cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a target information detection system according to the present invention.

FIG. 2 is a diagram illustrating an example of a time change characteristic of the polarization of a reflected wave of a target with a radio wave reflector in which the polarization of a reflected wave of a high-frequency modulation signal changes with time according to code information.

FIG. 3 is a diagram illustrating an operation principle of the target information detection system according to the first embodiment of the present invention.

FIG. 4 is a diagram showing Embodiment 2 of a target information detection system according to the present invention.

FIG. 5 is a diagram showing Embodiment 3 of a target information detection system according to the present invention.

FIG. 6 is a diagram illustrating an example of an FM-CW radar system when the FM-CW radar is mounted in front of a vehicle.

FIG. 7 is a diagram showing a conventional target information detection system.

FIG. 8 is a diagram showing the operation principle of a conventional FM-CW radar.

[Explanation of symbols]

1 road, 2a vehicle, 2b vehicle, 3 FM-CW radar, 4 obstacles, 5 people, 6 oscillators, 7 power distribution means, 8 antennas, 8a first antenna, 8b second antenna, 9 frequency converter, 10 distance and relative speed detection circuit, 11 target, 12 code detection circuit,
13. A target with a radio wave reflector in which the polarization of the reflected wave of the high-frequency modulation signal changes with time according to the code information;

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Tsubota 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsui Electric Co., Ltd. (72) Inventor Masato Sato 2-3-2 Marunouchi, Chiyoda-ku, Tokyo 3 F term in Ryo Denki Co., Ltd. (reference) 5J070 AB16 AB24 AC02 AC06 AD02 AE01 AE09 AE20 AF03 AH26 AH35 AH50 AK40 BA01 BF12

Claims (3)

[Claims] 1. A high-frequency modulation signal is transmitted toward a target, and a part of the transmission signal is converted into a local oscillation signal of a reception system to convert the frequency of a reception signal from the target, thereby obtaining a distance and a distance to the target. In the FM-CW radar system that obtains speed information, a part or the whole of the target is FM-C
A target with a radio wave reflector in which the polarization of the reflected wave of the high-frequency modulation signal transmitted from the W radar changes with time according to the code information, an oscillator for outputting the high-frequency modulation signal, and a part of the high-frequency modulation signal A power distributing unit that emits a signal and a remainder is a transmission signal, and a first antenna that irradiates the transmission signal to a target with a radio wave reflector whose polarization of a reflected wave of the high-frequency modulation signal changes with time according to the code information. A second antenna for receiving a reflected signal from a target with a radio wave reflector in which the polarization of the reflected wave of the high-frequency modulated signal changes with time according to the code information and outputting a received signal; the received signal; and the local oscillation signal And a frequency converter that outputs a video signal in accordance with the distance and relative speed of the target with the radio wave reflector whose polarization of the reflected wave of the high frequency modulation signal changes with time according to the code information. Bidet Fourier transforms the signal and analyzes it on the frequency axis, and the distance and relative distance for detecting the relative speed and the distance to the target with the radio wave reflector whose polarization of the reflected wave of the high-frequency modulated signal changes with time according to the code information The speed detection circuit and the video signal are analyzed on the time axis, and the output level of the video signal is compared with a threshold value and encoded. An FM-CW radar comprising: a code detection circuit for detecting code information of a changing target with a radio wave reflector. 2. Transmitting a high-frequency modulated signal toward a target, converting a part of the transmission signal as a local oscillation signal of a receiving system to a frequency of a received signal from the target, thereby obtaining a distance and a distance to the target. In a target information detection system for obtaining speed information, a target with a variable polarized radio wave reflector that can change the polarization of a reflected wave of a high-frequency modulation signal transmitted from an FM-CW radar by a control signal is used for part or all of the target. Object, a control unit that controls the polarization of the reflected wave of the target object with the variable polarization radio wave reflector, an oscillator that outputs a high-frequency modulation signal,
Power distribution means for using a part of the high-frequency modulated signal as a local oscillation signal and the remainder as a transmission signal, a first antenna for irradiating a transmission signal to the target with the variable polarization radio wave reflector, and the variable polarization radio wave reflector A second antenna that receives a reflection signal from the target and outputs a reception signal, receives the reception signal and the local oscillation signal, converts the frequency, and converts the frequency according to the distance and relative speed of the target with the variable polarization radio wave reflector. A frequency converter that outputs a video signal, a distance and relative speed detection circuit that detects a distance and a relative speed with the target with the variable polarization radio wave reflector by Fourier transforming the video signal and analyzing on a frequency axis, A code detection circuit that analyzes the video signal on a time axis, compares the output level of the video signal with a threshold value, and encodes the code information of the target with the variable polarization radio wave reflector. Be done Target information detection system characterized in that a M-CW radar. 3. The target information detection system according to claim 1, wherein the first antenna and the second antenna are shared by one antenna.