JP2001083246A - 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 absorber, in which a part or the whole of the target is constituted of a microwave absorber which absorbs 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 which corresponds to the frequency characteristic of the frequency selective absorber which constitutes 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. 8 shows an example 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 installed on the road side of the road 1. The obstacle 5 such as the installed telephone pole or the on-street parked vehicle parked on the road side, and the person 5 is 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 a irradiates the frequency-modulated transmission radio wave forward, the vehicle 2a running in front, the obstacle 4 and the human 5
Receiving the reflected waves from the vehicle, etc., detecting the strength, frequency shift due to Doppler and the propagation time of the radio wave, obtaining the distance and relative speed with the vehicle 2a from the results, and warning or brake control for collision prevention, etc. Used for safety measures.

[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. Then, analysis is performed on the frequency axis to detect information such as the distance to the target and the relative speed.

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]

According to a first aspect of the present invention, there is provided a target information detection system comprising: a radio wave absorber mounted on a target and having a characteristic of absorbing a specific frequency of an incident radio wave; Transmitting means for transmitting to the absorber, receiving means for receiving the radio wave reflected by the radio wave absorber, and a unique characteristic corresponding to the frequency characteristic of the radio wave absorber to be absorbed based on the signal received by the receiving means. Detecting means for detecting information.

Further, the target information detecting system according to the second aspect of the present invention is a radio wave absorber for absorbing a part or the whole of a target 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 absorber 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 absorber, A second antenna that receives a reflected signal from the target with a frequency-selective radio wave absorber and outputs a received signal, receives the received signal and the local oscillation signal, converts the frequency, and converts the target with the frequency-selective radio wave absorber. A frequency converter that outputs a video signal according to the distance and relative speed of the signal, outputs a pulse modulation signal to the pulse modulation means, analyzes the pulse modulation signal and the video signal on a time axis, and The distance of the target with the radio wave absorber 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 absorber 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 absorber is provided.

Further, the target information detecting system according to the third invention is such that the first and second antennas are shared by one antenna.

A target information detection system according to a fourth aspect of the present invention is a radio wave absorber mounted on a target, resonating at a specific frequency of an incident radio wave, and terminating an incident wave at the resonated frequency. A transmitting means for transmitting a radio-frequency-modulated radio wave to the radio wave absorber, a receiving means for receiving a radio wave reflected by the radio wave absorber, and a termination at the radio wave absorber based on a signal received by the receiving means. Detecting means for detecting unique information corresponding to the frequency characteristic to be performed.

A target information detection system according to a fifth aspect of the present invention transmits a high-frequency-modulated and pulse-modulated signal toward a target, and converts a part of the transmission signal as a local signal of a receiving system. In a target information detection system that obtains distance and speed information of a target from a video signal obtained by frequency-converting a received signal from the local oscillation signal, a high-frequency modulation signal transmitted from the FM pulse Doppler radar for part or all of the target. A target having a frequency-selective radio termination circuit having a circuit having means for terminating the high-frequency modulation signal that resonates at one or a plurality of specific frequencies, and outputting the high-frequency modulation signal An oscillator to perform, a power distribution unit using a part of the high-frequency modulated signal as a local oscillation signal and the remainder as a transmission reference signal, and pulse-modulating the transmission reference signal as a transmission signal. Pulse modulating means, first of irradiating said transmission signal to said frequency-selective radio termination circuit with the target
An antenna, a second antenna for receiving a reflected signal from the target with the frequency selective radio terminal circuit and outputting a received signal, receiving the received signal and the local oscillation signal, converting the frequency, and converting the frequency selective radio terminal signal A frequency converter that outputs a video signal according to the distance and relative speed of a target with a circuit,
A pulse modulated signal is output to the pulse modulating means, and the pulse modulated signal and the video signal are analyzed on a time axis to detect a distance of the target with the frequency selective radio terminal circuit, and the video signal is Fourier transform and analysis on the frequency axis, distance and relative speed detection circuit for detecting the distance and relative speed of the target with the frequency selective radio terminal circuit, and analysis of the video signal on the time axis, An FM pulse Doppler having a code detection circuit for detecting code information of the target with the frequency selective radio terminal circuit by judging whether or not the video signal is detected or not detected by a threshold value of a signal output level and encoding the target. It is equipped with a radar.

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

[0016]

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 absorber. Target 14 with frequency selective radio wave absorber
Is constituted by a radio wave absorber that absorbs one or more specific frequencies in a transmission signal transmitted from an FM pulse Doppler radar for part or all of a target.

FIG. 2 shows a target 14 with a frequency-selective radio wave absorber.
FIG. 4 is a diagram showing an example of the frequency characteristic of FIG. As shown in the figure,
The radio wave absorber absorbs 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 equal parts. In this example, it is constituted by a radio wave absorber that absorbs three different frequencies. The target 14 with the frequency-selective radio wave absorber configured as described above absorbs these three frequencies out of the modulation frequency width of the frequency transmitted from the FM pulse Doppler radar 3 and modulates the modulation frequencies other than the three. reflect.

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 toward the target 14 with the frequency-selective radio wave absorber. The target 14 with a frequency-selective radio wave absorber absorbs three frequencies shown in FIG. 2 in the modulation frequency width ΔF of the high-frequency modulation signal transmitted from the FM pulse Doppler radar 3 and totally reflects other frequencies. .
The second antenna 9b receives a reflected signal from the target 12, and outputs a received signal. 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. 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 a time axis,
In addition to detecting distance information to the target, the video signal is Fourier-transformed 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. The code information of the target 14 with the selective electromagnetic wave absorber 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 absorber from the pulse of the transmission signal.
Accordingly, by analyzing the pulse modulation signal and the video signal on the time axis from this relationship, the distance of the target 14 with the frequency-selective radio wave absorber can be detected. 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,
Of these, the thick line indicates the target 14
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 absorber. The received signal reflected and returned by the target 14 with the frequency-selective radio wave absorber is the target with the frequency-selective radio wave absorber.
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)
Beat frequency component corresponding to the target distance / speed like
It becomes a video signal with Fb. 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. 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. Fig. 4 (c)
As shown by the curve d, the level of the received signal of the beat signal changes in accordance with the frequency characteristic of the target 14 with the frequency-selective radio wave absorber. 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 the threshold value set in the code detection circuit 13, the code is set to "1", and when the video signal level is detected to be lower than "0", the code is set to "0". Thus, code information corresponding to the frequency characteristics of the target 14 with the frequency-selective radio wave absorber is detected. Also, by referring to code information stored in a memory (not shown) in advance (for example, information provided with a different code for each type or size of target), 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 absorber is detected. For example, target with frequency selective radio wave absorber
By mounting a frequency-selective radio wave absorber that gives specific code information for each 14, based on the code information detected by the code detection circuit 13, the type of target (for example, 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 a specific frequency band absorbed by the radio wave absorber to another value (other than 7) 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 wave absorber is detected by the target 14 with the frequency-selective radio wave absorber. , For example, information on the type of the target classified by the code can be obtained.

Embodiment 2 FIG. FIG. 5 shows an embodiment of the present invention.
FIG. 2 is a block diagram showing 2, in which 3, 6 to 11 are the same as those of the conventional target information detection system, 13 and 14 are the same as 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 absorber. The target 14 with a frequency-selective radio wave absorber absorbs three frequencies shown in FIG. 6 in the modulation frequency width Δf of the high-frequency modulation signal transmitted from the FM pulse Doppler radar 3 and totally reflects other frequencies. . The antenna 8 receives a reflected signal from the target 14 with the frequency-selective radio wave absorber and outputs a received signal. 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. 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 a time axis,
In addition to detecting distance information to the target, the video signal is Fourier-transformed 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, and determines the detected output level based on a set threshold to determine whether the video signal has been detected or not, and encodes the frequency. The code information of the target 14 with the selective electromagnetic wave absorber 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 wave absorber is detected by the target 14 with the frequency selective radio wave absorber. , 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. 6 shows an embodiment of the present invention.
3 is a block diagram showing 3, in which 3, 6 to 11 are the same as the conventional target information detection system, 13 is the same as that described in the configuration diagram of the first embodiment, 16 is the frequency It is a target with a selective radio wave termination circuit. The target 16 with a frequency-selective radio terminal circuit resonates a part or the whole of the target at one or more specific frequencies in a transmission signal transmitted from the FM pulse Doppler radar. It is constituted by a terminating circuit having means for terminating the harmonic modulation signal. For example, a terminator made of a resistor or the like is attached to a patch antenna that resonates at a specific frequency.

FIG. 7 shows a target 1 with a frequency selective radio wave terminating circuit.
6 is a diagram illustrating an example of a frequency characteristic of FIG. As shown in the figure, the radio wave absorber terminates 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 equal parts.
In this case, a termination circuit for terminating three different frequencies is provided. The target 16 with the frequency-selective radio terminal circuit configured in this manner is one of the modulation frequency widths of the transmission signal transmitted from the FM pulse Doppler radar 3.
The three frequencies are terminated, and the modulation frequencies other than the three are reflected.

Next, the operation will be described. In FIG. 6, 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 toward the target 16 with the frequency selective radio wave terminating circuit. The target 16 with the frequency selective radio terminal circuit terminates three frequencies shown in FIG. 6 in the modulation frequency width ΔF of the high-frequency modulation signal transmitted from the FM pulse Doppler radar 3 and totally reflects other frequencies. . The second antenna 9b receives a reflected signal from the target 12, and outputs a received signal. 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. Then, analysis is performed on the frequency axis to detect information such as the distance to the target and the relative speed. Code detection circuit 13
Detects the output level of the video signal on a time axis,
The detected output level is determined based on a set threshold value to determine whether the video signal is detected or not detected, and the encoded information is encoded to detect the code information of the target 16 having the frequency selective radio terminal circuit.

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 terminal circuit is detected by the target 16 with the frequency selective radio terminal circuit. , For example, information on the type of the target classified by the code can be obtained.

Embodiment 4 FIG. 8 shows an embodiment of the present invention.
FIG. 4 is a block diagram showing 4, in which 3, 7 to 11 are the same as the conventional target information detection system, 13, 15 are the same as those described in the configuration diagram of the second embodiment, and 16 is the embodiment. It is the same as that described in the configuration diagram of FIG.

Next, the operation will be described. In FIG. 8, the 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 16 with the frequency selective radio wave termination circuit. The target 16 with a frequency-selective radio terminal circuit terminates the three frequencies shown in FIG. 6 in the modulation frequency width Δf of the high-frequency modulation signal transmitted from the FM pulse Doppler radar 3 and totally reflects other frequencies. . Antenna 8 is
Upon receiving a reflected signal from the target 16 with a frequency-selective radio terminal circuit, it outputs a received signal. 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. Then, analysis is performed on the frequency axis to detect information such as the distance to the target and the relative speed. Code detection circuit 13
Detects the output level of the video signal on a time axis,
The detected output level is determined based on a set threshold value to determine whether the video signal is detected or not detected, and the encoded information is encoded to detect the code information of the target 16 having the frequency selective radio terminal circuit.

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 terminal circuit is detected by the target 16 with the frequency selective radio terminal circuit. , 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.

[0033]

According to the first aspect of the present invention, a high-frequency modulated radio wave is transmitted to a radio wave absorber that absorbs a specific frequency, so that the received wave reflected by the radio wave absorber can be used to convert the radio wave absorber. Can be detected. As a result, it is possible to identify a target on which the radio wave absorber is mounted.

According to the second aspect of the present invention, the frequency-selective radio wave absorber includes a target having the frequency-selective radio wave absorber constituted by one or more frequency-selective radio wave absorbers, and It is possible to obtain code information of a target corresponding to a characteristic. As a result, there is an effect that information for identifying the target can be obtained in addition to the distance and the relative speed to the target.

According to the third aspect of the present invention, the target having the frequency-selective radio wave absorber constituted by one or more frequency-selective radio wave absorbers and the frequency of the frequency-selective radio wave absorber are determined by the code detection circuit. It is possible to obtain code information of a target corresponding to a characteristic. As a result, there is an effect that information for identifying the target can be obtained in addition to the distance and the relative speed to the target. 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.

According to the fourth aspect of the present invention, by transmitting a high-frequency modulated radio wave to a radio wave absorber that resonates at a specific frequency and has a characteristic of terminating an incident wave of the resonated frequency, Specific information corresponding to the radio wave absorber can be detected from the received wave reflected by the radio wave absorber. As a result, it is possible to identify a target on which the radio wave absorber is mounted.

According to the fifth aspect of the present invention, a target having a frequency selective radio terminal circuit constituted by one or a plurality of frequency selective radio terminal circuits and a frequency of the frequency selective radio terminal circuit are determined by a code detection circuit. It is possible to obtain code information of a target corresponding to a characteristic. As a result, there is an effect that information for identifying the target can be obtained in addition to the distance and the relative speed to the target.

Further, according to the sixth aspect of the present invention, a target having a frequency selective radio terminal circuit constituted by one or a plurality of frequency selective radio terminal circuits and a code detecting circuit are used to form a frequency selective radio terminal circuit. Code information of a target corresponding to the frequency characteristic can be obtained. as a result,
There is an effect that information for identifying the target can be obtained in addition to the distance and the relative speed to the target. 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 frequency characteristics of a target 14 with a frequency-selective radio wave absorber.

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 showing Embodiment 3 of a target information detection system according to the present invention.

FIG. 7 is a diagram showing an example of the frequency characteristics of the target 16 with a frequency-selective radio terminal.

FIG. 8 is a diagram showing a fourth embodiment of the target information detection system according to the present invention.

FIG. 9 is a diagram showing an example of a usage state of a conventional target information detection system.

FIG. 10 is a diagram showing a conventional target information detection system.

FIG. 11 is a diagram showing a time chart of a conventional target information detection system.

FIG. 12 is a diagram showing the operation principle of a conventional target information detection system.

[Explanation of symbols]

 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 Object 13 Code detection circuit 14 Target with frequency selective radio wave absorber 15 Transmission / reception switching means 16 Target with frequency selective radio wave termination circuit

Continued on the front page F term (reference) 5H180 AA01 AA21 BB04 CC12 CC14 CC15 LL01 LL04 LL06 LL08 LL09 5J070 AB08 AC02 AC06 AD01 AD02 AE01 AE09 AE20 AF03 AH14 AH25 AH33 AH35 AH50 AK13 AK27 BF30 BF40 BF40

Claims (6)

[Claims] 1. A radio wave absorber mounted on a target and having a characteristic of absorbing a specific frequency of an incident radio wave, a transmitting means for transmitting a radio frequency modulated radio wave to the radio wave absorber,
Receiving means for receiving the radio wave reflected by the radio wave absorber, and detecting means for detecting unique information corresponding to a frequency characteristic absorbed by the radio wave absorber based on a signal received by the receiving means. Target information detection system. 2. 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 signal of a receiving system, and a received signal from the target is frequency-divided by the local signal. In a target information detection system that obtains distance and velocity information of a target from the converted video signal, a part or the whole of the target is one or more specific frequencies in a transmission signal transmitted from an FM pulse Doppler radar. Target having a frequency-selective radio wave absorber having a radio wave absorber for absorbing radio waves, an oscillator for outputting a high-frequency modulation signal, and power distribution with a part of the high-frequency modulation signal as a local oscillation signal and the remainder as a transmission reference signal Means, 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 the frequency-selective radio wave absorber, and the frequency A second antenna that receives a reflected signal from the target with a selective radio wave absorber and outputs a reception signal, converts the frequency of the received signal and the local oscillation signal to receive the local oscillation signal, and converts the frequency of the target with the frequency selective radio wave absorber. A frequency converter for outputting a video signal according to a distance and a relative speed; outputting a pulse modulation signal to the pulse modulation means; analyzing the pulse modulation signal and the video signal on a time axis;
Detect the distance of the target with the frequency-selective radio wave absorber,
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 absorber, and the video signal on the time axis. A code detection circuit for analyzing and detecting the code level of the target with the frequency-selective radio wave absorber by determining and encoding the detection or non-detection of the video signal by a threshold value of the output level of the video signal; A target information detection system, comprising: an FM pulse Doppler radar having the following. 3. The target information detection system according to claim 2, wherein the first and second antennas are shared by one antenna. 4. A radio wave absorber mounted on a target and resonating at a specific frequency of an incident radio wave, and having a characteristic of terminating an incident wave of the resonated frequency, and a radio frequency modulated radio wave applied to the radio wave absorber. Transmitting means for transmitting, receiving means for receiving the radio wave reflected by the radio wave absorber, and unique information corresponding to a frequency characteristic terminated by the radio wave absorber based on a signal received by the receiving means. A target information detection system comprising: a detection unit for detecting. 5. 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 signal of a receiving system, and a received signal from the target is frequency-converted by the local signal. In a target information detection system that obtains distance and velocity information of a target from the converted video signal, a part or the whole of the target is specified by one or more specific one or more of high-frequency modulation signals transmitted from an FM pulse Doppler radar. A target having a frequency-selective radio termination circuit having a circuit that resonates at a frequency and has a means for terminating the resonated high-frequency modulation signal, an oscillator that outputs a high-frequency modulation signal, and a part of the high-frequency modulation signal. Power distribution means for generating 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 selecting the transmission signal for frequency selection A first antenna for irradiating a target with a radio wave terminating circuit, a second antenna for receiving a reflected signal from the target with a frequency selective radio terminating circuit and outputting a received signal, A frequency converter that receives and converts the frequency, and outputs a video signal according to the distance and relative speed of the target having the frequency selective radio terminal circuit, and outputs a pulse modulation signal to the pulse modulation means, And analyzing the video signal on the time axis, detecting the distance of the target with the frequency selective radio terminal circuit, and performing Fourier transform on the video signal and analyzing on the frequency axis, the frequency selective radio terminal A distance and relative speed detection circuit for detecting a distance and a relative speed of a target with a circuit, and analyzing the video signal on a time axis, and raising an output level of the video signal by a threshold value An FM pulse Doppler radar having a code detection circuit for detecting code information of the target with the frequency selective radio terminal circuit by judging and encoding detection or non-detection of a video signal. Target information detection system. 6. The target information detection system according to claim 5, wherein said first and second antennas are shared by one antenna.