JP2001083245A - Target-information detecting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a target-information detecting system in which information used to discriminate a target is obtained in addition to a distance up to the target and its relative speed. SOLUTION: This target-information detecting system is constituted of a target 14 equipped with a frequency selective reflector, in which a part or the whole of the target is constituted of a radio-wave reflector which reflects one or a plurality of specific frequencies in a high-frequency modulation signal which is transmitted from an FM pulse Doppler radar 3. The target-information detecting system is constituted of the FM pulse Doppler radar 3 which is composed of an oscillator 6, a power distribution means 7, a pulse modulation means 8, a first antenna 9a, a second antenna 9b, a frequency converter 10, a distance and relative-speed detection circuit 11, and a code detection circuit 13. As a result, in addition to a distance up to the target and its relative speed, it is possible to obtain code information on the target which corresponds to the frequency characteristic of the frequency selective reflector constituting the target.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on a moving body such as an automobile or a roadside machine installed along a road, and is mounted on a mounted moving body or a roadside machine such as a person, a vehicle and an obstacle. The present invention relates to a target information detection system that detects a target using radio waves and detects information on the detected target.

[0002]

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

[0003] Next, the use situation will be described. Road 1
The FM pulse Doppler radar 3 mounted on the vehicle 2b passing in the direction of b irradiates the frequency-modulated and pulse-modulated transmission radio wave forward, and the vehicle 2 traveling ahead
a, receives reflected waves from obstacles 4 and humans 5, etc., detects the strength, frequency shift due to Doppler, and the propagation time of radio waves, and calculates the distance and relative speed with the vehicle 2a from the results, preventing collision It is used for safety measures such as warnings for brakes or brake control.

[0004] Regarding the usage status of such a system, see, for example, IEICE Technical Report MW94-48 (1994-09) "Development of Millimeter-Wave Application System in Japan" and Nihon Keizai Shimbun "IT
All of S "(1995) P62-67.

FIG. 7 shows a configuration diagram of the conventional target information detection system shown in FIG. 6, in which 6 is an oscillator, 7 is power distribution means, 8 is pulse modulation means, and 9a and 9b are first and second systems. An antenna, 10 is a frequency converter, 11 is a distance and relative speed detection circuit, and 12 is a target.

Next, the operation will be described. In FIG. 7, an oscillator 6 outputs a high-frequency modulation signal (of FRF ± ΔF, FRF is a center frequency and ΔF is a modulation frequency width).
The power distribution unit 7 outputs a part of the high-frequency modulated signal as a local oscillation signal and the rest as a transmission reference signal to the pulse modulation unit 8. The pulse modulating means 8 pulse-modulates the input high-frequency modulated signal with a pulse modulated signal output from the distance and relative speed detection circuit 11, and outputs the modulated signal to the first antenna 9a as a transmission signal. The first antenna 9a outputs a transmission signal toward the target 12. The second antenna 9b is connected to the target 12
And outputs a received signal in response to the reflected signal from the The frequency converter 10 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 11 outputs a pulse modulation signal to the pulse modulation means, analyzes the pulse modulation signal and the video signal on the time axis, detects distance information from the target, and performs a Fourier transform on the video signal. The analysis is performed on the frequency axis, and information such as the distance to the target and the relative speed is detected based on the analysis result.

Next, the operation will be supplementarily described. 8 and 9 show the principle of operation of a conventional target information detection system. 8 (a) shows the output of the oscillator 6, FIG. 8 (b) shows a pulse modulation signal, FIG. 8 (c) shows a transmission signal (PRF is a pulse repetition time),
8 (d) shows a time chart of a local signal, FIG. 8 (e) shows a time chart of a received signal, and FIG. 8 (f) shows a time chart of a video signal. Thus, the pulse of the received signal has a delay time twice as long as the target distance from the pulse of the transmitted signal. Therefore, the target distance can be detected by analyzing the pulse modulation signal and the video signal on the time axis from this relationship. Further, a curve a in FIG. 9A is a local oscillation signal (of frequencies FRF ± ΔF, FRF is a center frequency, ΔF is a modulation frequency width), and a curve b is a received signal. In a conventional FM pulse Doppler radar, a target is irradiated with a frequency-modulated and pulse-modulated transmission signal, the received signal has a delay time twice as long as the distance to the target, and the received signal is frequency-converted by a local oscillation signal ( The video signal has a beat frequency component Fb corresponding to the target distance / speed as shown by a curve c in FIG. 9B. Next, the distance and relative speed detection circuit 11 calculates the distance to the target from the time from when the transmission signal is transmitted to when the reception signal is received, and calculates the distance and the relative speed to the target from the frequency Fb. . Here, for simplicity of 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 configured as described above, information on the distance and relative speed of the target can be obtained, but other information such as the type and size of the target can be obtained. There is a problem that information unique to the indicated goal cannot be obtained, and thus the goal cannot be identified.

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

[0010]

A target information detection system according to a first aspect of the present invention includes a radio wave reflector mounted on a target and having a characteristic of reflecting a specific frequency, and transmitting a radio frequency modulated radio wave to the radio wave reflector. Transmitting means, receiving means for receiving a radio wave reflected from the radio wave reflector, and detecting means for detecting unique information corresponding to the reflection characteristic of the radio wave reflector based on a signal received by the receiving means. It is provided with.

Further, in the target information detection system according to the second invention, the detection means detects code information as the unique information.

In the target information detecting system according to a third aspect of the present invention, the radio wave reflector is mounted on a known target, and the unique information detected by the detecting means is the type or size of the known target. Is used as information for identifying.

Further, in the target information detection system according to a fourth aspect of the present invention, the radio wave reflector is mounted on a vehicle, and the transmitting means and the receiving means are mounted on a vehicle different from the vehicle or on a road machine.

Further, in the target information detecting system according to the fifth invention, the radio wave reflector is different for each vehicle mounted,
It has information for specifying the vehicle.

The target information detection system according to a sixth aspect of the present invention is a radio wave reflection system for reflecting a part or the whole of a target object at one or a plurality of specific frequencies in a transmission signal transmitted from an FM pulse Doppler radar. A target having a frequency-selective radio wave reflector having a body, an oscillator for outputting a high-frequency modulation signal, and a part of the high-frequency modulation signal as a local oscillation signal;
Power distributing means for using the remainder as a transmission reference signal, pulse modulation means for pulse-modulating the transmission reference signal to generate a transmission signal, a first antenna for irradiating the transmission signal to the target with a frequency-selective radio wave reflector, A second antenna that receives a reflected signal from the target with a frequency-selective radio wave reflector and outputs a reception signal, receives the reception signal and the local oscillation signal, converts the frequency, and converts the frequency with the target with a frequency-selective radio wave reflector. A frequency converter for outputting a video signal according to the distance and relative speed of the signal, outputting a pulse modulation signal to the pulse modulation means, analyzing the pulse modulation signal and the video signal on a time axis, The distance of the target with the radio wave reflector is detected, and the video signal is Fourier transformed and analyzed on the frequency axis, and the distance and the relative speed of the target with the frequency selective radio wave reflector are calculated. A circuit for detecting the distance and relative speed to be output, and the video signal are analyzed on a time axis, and the output level of the video signal is determined by detecting or not detecting the video signal based on a threshold value and encoded, thereby encoding the frequency. An FM pulse Doppler radar having a code detection circuit for detecting code information of a target with a selective radio wave reflector is provided.

Further, in the target information detecting system according to a seventh aspect, the first and second antennas are shared by one antenna.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing Embodiment 1 of the present invention.
Reference numerals 3, 6 to 11 are the same as those of the conventional target information detection system, 13 is a code detection circuit, and 14 is a target with a frequency-selective radio wave reflector. Target 14 with frequency selective radio wave reflector
Is constituted by a radio wave reflector that reflects one or more specific frequencies in a transmission signal transmitted from the FM pulse Doppler radar for part or all of the target. Further, as the radio wave reflector, one that resonates at a certain specific frequency and radiates radio waves, such as an array antenna composed of a plurality of radiation conductor elements, is used.

FIG. 2 shows a target 14 with a frequency-selective radio wave reflector.
FIG. 4 is a diagram showing an example of the frequency characteristic of FIG. As in the example shown in the figure, the radio wave reflector totally reflects radio waves of a specific frequency in a frequency band obtained by dividing the modulation frequency width of the high-frequency modulation signal into seven. In this example, it is composed of a radio wave reflector that reflects three different frequencies. The target 14 with the frequency-selective radio reflector configured in this way is an FM pulse Doppler radar.
Of the modulation frequency width of the frequency transmitted from 3, only these three frequencies are totally reflected.

Next, the operation will be described. In FIG. 1, an oscillator 6 outputs a high-frequency modulation signal (of FRF ± ΔF, FRF is a center frequency and ΔF is a modulation frequency width).
The power distribution unit 7 converts a part of the high-frequency modulated signal into a local oscillation signal, and outputs the rest to the pulse modulation unit 8. The pulse modulating means 8 pulse-modulates the input high-frequency modulated signal with a pulse modulated signal output from the distance and relative speed detection circuit 11, and outputs the modulated signal to the first antenna 9a as a transmission signal. First
The antenna 9a outputs the transmission signal to the target 14 with the frequency selective radio wave reflector. The target 14 with the frequency-selective radio wave reflector totally reflects three frequencies shown in FIG. 2 in the modulation frequency width ΔF of the transmission signal transmitted from the FM pulse Doppler radar 3. The second antenna 9b receives a reflected signal from the target 12, and outputs a received signal. Frequency converter
10 receives the received signal and the local oscillation signal and outputs a video signal having the sum and difference frequencies of the two. The distance and relative speed detection circuit 11 outputs a pulse modulation signal to the pulse modulation means, analyzes the pulse modulation signal and the video signal on the time axis, detects information on the distance to the target, and Fourier transforms the video signal. The data is converted and analyzed on the frequency axis to detect information such as the distance to the target and the relative speed.
The code detection circuit 13 detects the output level of the video signal on the time axis, determines whether the video signal is detected or not detected based on a set threshold value, and encodes the detected output level. Target 14 with selective radio wave reflector
Code information is detected.

Next, the operation will be supplementarily described. 3 and 4 show the operation principle of the target information detection system according to the present invention. 3 (a) shows the output of the oscillator 6, FIG. 3 (b) shows a pulse modulation signal, FIG. 3 (c) shows a transmission signal (PRF is a pulse repetition time), FIG. 3 (d) shows a local oscillation signal, and FIG. e) shows a time chart of the received signal, and FIG. 3 (f) shows a time chart of the video signal. As described above, the pulse of the reception signal has a delay time twice as long as the distance of the target 14 with the frequency selective radio wave reflector from the pulse of the transmission signal.
Therefore, the distance between the target 14 with the frequency-selective radio wave reflector can be detected by analyzing the pulse modulation signal and the video signal on the time axis from this relationship. Also, the curve a in FIG. 4A is a local signal (of the frequency FRF ± ΔF, where FRF is the center frequency,
ΔF is the modulation frequency width), curve b is the received signal,
The bold line indicates the target 14 with the frequency selective radio wave reflector.
Corresponds to the portion reflected and received by The FM pulse Doppler radar irradiates the frequency-modulated and pulse-modulated transmission signal to the target 14 with the frequency-selective radio wave reflector. The received signal reflected by the target 14 with the frequency-selective radio reflector is returned to the target with the frequency-selective radio reflector.
A delay time occurs twice as long as the distance to 14, and the frequency is converted (homodyne detection) by the local oscillation signal. The curve c in FIG. 4 (b)
Is a video signal having a beat frequency component Fb corresponding to the distance / speed of the target. The distance and relative speed detection circuit 11 calculates the distance to the target and the relative speed from the frequency Fb of the bead signal. For simplicity of explanation here, if your own speed and the target speed are the same,
That is, the case where the relative speed = 0 is shown. Also, figure
As shown by the curve d in FIG. 4C, the level of the received signal of the beat signal changes in accordance with the frequency characteristics of the target 14 with the frequency selective radio wave reflector. The code detection circuit 13 detects the level of the video signal. For example, when the video signal level is detected to be higher than a threshold value set in the code detection circuit 13, it is set to "1", and when the video signal level is detected to be lower than "0", the code is set to "0". Thus, the code information corresponding to the frequency characteristics of the target 14 with the frequency selective radio wave reflector is detected. Also, reference is made to code information stored in a memory (not shown) in advance (for example, information provided with a different code for each type or size classification of a target), and the detected code information and the information stored in the memory are referred to. By comparing the code information with the code information, the unique information of the target corresponding to the target 14 with the frequency selective radio wave reflector is detected. For example, target with frequency selective radio wave reflector
By mounting a frequency-selective radio wave reflector that gives specific code information for each 14, the type of target (for example, if the target is a large vehicle or Such as a small vehicle)
And information such as the size (for example, that the vehicle width and the vehicle height of the target vehicle are within a predetermined range). FIG.
In the example, the code for 14 bits is shown.
(The bit and the last 7 bits have a symmetric data structure.)
However, by setting the width of the specific frequency band reflected by the radio wave reflector to another value (other than 7 equal parts) of the modulation frequency width in the high frequency modulation signal and setting the width of the frequency band, It goes without saying that the number can be set to another value.

In the target information detection system configured as described above, the distance and the relative speed to the target are detected, and the frequency characteristic of the frequency-selective radio reflector is determined by the target 14 with the frequency-selective radio reflector. , It is possible to obtain the code information of the target corresponding to, for example, information of the type of the target classified by the code. Also, by giving a code indicating the size of the target as code information, the size of the target can be identified.

Embodiment 2 FIG. FIG. 5 is a block diagram showing a second embodiment of the present invention, in which 3, 6 to 11 are the same as the conventional target information detection system, and 13 to 14 are those described in the configuration diagram of the first embodiment. And 15 is transmission / reception switching means.

Next, the operation will be described. In FIG. 5, an oscillator 6 outputs a high-frequency modulation signal (of FRF ± ΔF, FRF is a center frequency and ΔF is a modulation frequency width).
The power distribution unit 7 converts a part of the high-frequency modulated signal into a local oscillation signal, and outputs the rest to the pulse modulation unit 8. The pulse modulating means 8 pulse-modulates the input high-frequency modulated signal with the pulse modulated signal output from the distance and relative speed detection circuit 11, and outputs a transmission signal. The transmission / reception switching means 15 guides the transmission signal to the antenna 8 and guides the reception signal output from the antenna 8 to the frequency converter 10. The antenna 8 outputs the transmission signal to the target 14 with the frequency selective radio wave reflector. The target 14 with a frequency-selective radio wave reflector totally reflects three frequencies shown in FIG. 2 in the modulation frequency width Δf of the transmission signal transmitted from the FM pulse Doppler radar 3.
The antenna 8 receives a reflected signal from the target 14 with a frequency-selective radio wave reflector and outputs a received signal. Frequency converter
10 receives the received signal and the local oscillation signal and outputs a video signal having the sum and difference frequencies of the two. The distance and relative speed detection circuit 11 outputs a pulse modulation signal to the pulse modulation means, analyzes the pulse modulation signal and the video signal on the time axis, detects distance information from the target, and performs a Fourier transform on the video signal. Then, analysis is performed on the frequency axis to detect information such as the distance to the target and the relative speed. The code detection circuit 13 detects the output level of the video signal on the time axis, determines whether the video signal is detected or not detected based on a set threshold value, and encodes the detected output level. The code information of the target 14 with the selective radio wave reflector 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 frequency characteristic of the frequency-selective radio reflector is determined by the target 14 with the frequency-selective radio reflector. , For example, information on the type of the target classified by the code can be obtained.

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.

Embodiment 3 FIG. In the embodiment of the present invention, the target 14 with the frequency-selective radio wave reflector described in the first or second embodiment is a vehicle, and a different frequency-selective radio wave reflector is mounted for each vehicle. Also, code detection circuit
A transmission device (not shown) for transmitting the detected code information to a central management device (not shown) (wirelessly or by wire) is provided in the unit 13. The central management device is provided with a vehicle identification circuit that identifies the vehicle by comparing the preset vehicle identification information with the code information transmitted from the code detection circuit 13. The vehicle identification circuit has, as identification information of the vehicle, for example, number information of all or some number plates installed in the vehicle and code information corresponding to each number information in an internal memory. further,
As the code information detected by the code detection circuit 13 corresponds to the number information of the vehicle possessed by the vehicle identification circuit,
A specific frequency characteristic is given to the frequency-selective radio wave reflector mounted on each vehicle.

In the target information detection system configured as described above, the code information detected and transmitted by the code detection circuit 13 in the vehicle identification circuit is compared with the code information held in the memory in association with the number information. This makes it possible to extract the number information of the vehicle equipped with the frequency-selective radio wave reflector and specify the vehicle. In this case, as a frequency characteristic of the radio wave reflector, for example, the modulation frequency width is divided into 14 and a characteristic of giving 14 bits of code information is provided, so that four digits can be identified for the number information of the license plate. .

[0028]

According to the first to fifth aspects of the present invention, a high-frequency modulated radio wave is transmitted to a radio wave reflector that reflects a specific frequency, so that a received wave reflected by the radio wave reflector is converted to a radio wave. The unique information corresponding to the radio wave reflector can be detected. As a result, it is possible to identify a target on which the radio wave reflector is mounted.

According to the sixth aspect of the present invention, the frequency characteristic of the frequency-selective radio wave reflector is obtained by using the target with the frequency-selective radio wave reflector constituted by one or more frequency-selective radio wave reflectors and the code detection circuit. Can be obtained. As a result, the target can be identified in addition to the distance to the target and the relative speed.

According to the seventh aspect of the present invention, the frequency-selective radio wave reflector includes a target having a frequency-selective radio wave reflector constituted by one or a plurality of frequency-selective radio wave reflectors, and a code detecting circuit. It is possible to obtain target code information corresponding to characteristics. As a result, in addition to the distance and the relative speed to the target, there is an effect that the target can be identified. In addition, since the antenna is shared for transmission and reception, one antenna can be omitted, so that there is an effect that the size and cost of the device can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an example of a frequency characteristic of a target with a frequency-selective radio wave reflector.

FIG. 3 is a diagram showing a time chart of Embodiment 1 of the target information detection system according to the present invention.

FIG. 4 is a diagram illustrating an operation principle of the target information detection system according to the first embodiment of the present invention.

FIG. 5 is a diagram showing Embodiment 2 of a target information detection system according to the present invention.

FIG. 6 is a diagram illustrating an example of a usage status of a conventional target information detection system.

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

FIG. 8 is a diagram showing a time chart of a conventional target information detection system.

FIG. 9 is a diagram showing the operation principle of a conventional target information detection system.

[Description of Signs] 1 Road 2a Vehicle 2b Vehicle 3 FM pulse Doppler radar 4 Obstacle 5 Human 6 Oscillator 7 Power distribution means 8 Pulse modulation means 9 Antenna 9a First antenna 9b Second antenna 10 Frequency converter 11 Distance and relative Speed detection circuit 12 Target 13 Code detection 14 Target with frequency-selective radio reflector 15 Transmission / reception switching means

Continued on the front page F-term (reference) 5H180 AA01 AA21 CC12 CC14 CC15 LL01 LL04 LL06 LL09 5J070 AB08 AC02 AC06 AC20 AD01 AD02 AE01 AE08 AE20 AF01 AF03 AH14 AH25 AH31 AH33 AH35 AJ13 AK15 AK27 BA01 BC13 BC30 BC30

Claims (7)

[Claims] 1. A radio wave reflector mounted on a target object and having a characteristic of reflecting a specific frequency, transmitting means for transmitting a radio frequency modulated radio wave to the radio wave reflector, and receiving a radio wave reflected from the radio wave reflector A target information detection system, comprising: a receiving unit that performs detection; and a detecting unit that detects unique information corresponding to a reflection characteristic of the radio wave reflector based on a signal received by the receiving unit. 2. The target information detection system according to claim 1, wherein said detection means detects code information as said unique information. 3. The radio wave reflector is mounted on a known target, and the unique information detected by the detecting means is information for identifying the type or size of the known target. The target information detection system according to claim 1. 4. The radio wave reflector is mounted on a vehicle, and the transmitting means and the receiving means are mounted on a vehicle different from the vehicle or on a road machine.
The target information detection system according to any one of the above. 5. The target information system according to claim 4, wherein the radio wave reflector is different for each mounted vehicle and has information for specifying the vehicle. 6. A high-frequency-modulated and pulse-modulated signal is transmitted toward a target, and a part of the transmission signal is used as a local oscillation signal of a receiving system. In a target information detection system that obtains distance and velocity information of a target from the converted video signal, one or more specific frequencies in a transmission signal transmitted from an FM pulse Doppler radar in part or in whole of the target. A target having a frequency-selective radio-reflector having a radio-reflector that reflects light, an oscillator for outputting a high-frequency modulated 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 reference signal, pulse modulation means for pulse-modulating the transmission reference signal to generate a transmission signal, and transmitting the transmission signal as the frequency-selective radio wave reflection The first to irradiate the target with body
An antenna, a second antenna that receives a reflected signal from the target with the frequency-selective radio wave reflector and outputs a received signal,
A frequency converter that receives the received signal and the local oscillation signal, converts the frequency, and outputs a video signal corresponding to the distance and relative speed of the target with the frequency-selective radio wave reflector; While outputting the pulse modulated signal and the video signal on a time axis,
Detecting the distance of the target with the frequency selective radio wave reflector,
And a distance and relative speed detection circuit for Fourier transforming the video signal and analyzing on the frequency axis to detect the distance and relative speed of the target with the frequency selective radio wave reflector, and the video signal on the time axis. A code detection circuit for analyzing and encoding the output level of the video signal by judging whether the video signal is detected or non-detected by a threshold and encoding the code information of the target with the frequency-selective radio wave reflector; A target information detection system, comprising: an FM pulse Doppler radar having the following. 7. The target information detection system according to claim 6, wherein the first and second antennas are shared by one antenna.