JP2000019246A - Obstacle detection system, radar device, and transponder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an obstacle detection system for accurately identifying the type of an obstacle, especially an obstacle that a vehicle has a possibility to collide with during driving, a radar device suited for the construction of the obstacle detection system, and a transponder. SOLUTION: The transponder 40 for returning a received radar wave by modulating its amplitude by a modulation signal Mc with a frequency fc is mounted on each vehicle. Also, the radar device 10 in an FMCW system for detecting an obstacle in front of the vehicle by transmitting and receiving radar waves is provided with a bandpass filter 30 for extracting a signal component near the frequency fc, namely a signal being modulated by the transponder 40 from a signal IF where a local signal L is mixed with a reception signal Sr, a mixer 34 for generating a second beat signal Sb2 by mixing a second local signal Lc with a frequency fc with an extraction signal IFm, and an A/D converter 36 for supplying the signal to an ECU 10b by converting it from analog to digital.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an obstacle detection system for transmitting and receiving radar waves to detect an obstacle, and a radar device and a transponder used in the obstacle detection system.

[0002]

2. Description of the Related Art Conventionally, radar waves such as microwaves and millimeter waves have been transmitted toward the front of an automobile, reflected waves have been received, and obstacles ahead have been detected based on these transmission / reception signals. An in-vehicle obstacle detection system that determines the distance and relative speed to the obstacle is known. The detection result of this obstacle detection system is described in, for example,
As disclosed in Japanese Patent No. 89400 and the like, it is used for various controls performed to avoid collision with an obstacle, maintain a safe distance from the obstacle, and the like.

FIG. 5 is a block diagram showing a general configuration of an FMCW type radar device used in this kind of obstacle detection system for a vehicle. That is, in the radar device 110 shown in FIG. 5, a voltage controlled oscillator 12 for generating a high frequency signal in a microwave band,
And a D / A converter 14 for generating a modulation signal M for changing the oscillation frequency (ie, the frequency of the high-frequency signal), and the high-frequency signal generated by the voltage-controlled oscillator 12 for power distribution. A directional coupler 16 that generates a signal L, a transmission antenna 18 that radiates a transmission signal Ss supplied from the directional coupler 16 as a radar wave,
A receiving antenna 20 for receiving a radar wave, a mixer 22 for mixing a received signal Sr from the receiving antenna 20 with a local signal L from the directional coupler 16, and a signal IF generated by the mixer 22, A low-pass filter (LPF) 24 for extracting a beat signal Sb which is a frequency component of a difference between the received signal Sr and the local signal L, and an A for converting the beat signal Sb extracted by the LPF 24 into a digital value.
The D converter 26 and the DA converter 14 supply modulation data Dm for generating the modulation signal M to the D / A converter 14 and, based on the data Db taken in through the AD converter 26, reflect an obstacle that reflects a radar wave. Control the engine operating conditions and brakes based on the calculation results to avoid collision with obstacles and maintain a safe inter-vehicle distance with the vehicle ahead. An electronic control unit (hereinafter referred to as an ECU) 28 for executing processing is provided.

The ECU 28 has a CPU, ROM, R
It is mainly composed of a well-known microcomputer made up of an AM, and includes an arithmetic processing unit and the like for executing a fast Fourier transform (FFT) process on data fetched via the AD converter 26. In the radar device 110 configured as described above, first, the ECU 28 supplies the D / A converter 14 with the modulation data Dm.
The A converter 14 generates a modulation signal M having a triangular waveform. Then, according to the modulation signal M, the voltage controlled oscillator 12
A high-frequency signal in a microwave band modulated into a triangular wave so that the frequency is linearly converted with respect to time is output. The high-frequency signal is divided into the transmission signal Ss and the local signal L by the directional coupler 16, and the transmission antenna 18 receiving the supply of the transmission signal Ss transmits a radar wave according to the transmission signal Ss.

When the receiving antenna 20 receives the radar wave reflected by an obstacle (not shown) and returned, the received signal Sr is mixed with the local signal L from the directional coupler 16 by the mixer 22. You. Mixer 22 at this time
The LPF 24 extracts a beat signal Sb, which is a frequency component of a difference between the two signals Sr and L, from the signal IF generated by the A / D converter 26, and converts the extracted beat signal Sb into an AD converter 26.
Is converted into digital data Db and supplied to the ECU 28.

[0006] Then, the ECU 28 performs FFT (fast Fourier transform) processing based on the data Db from the AD converter 26 to detect the peak frequency component of the beat signal Sb and specify the frequency. Based on the specified frequency, the distance and the relative speed with respect to the obstacle that generated the peak frequency component are calculated. Further, based on the calculation results, the operation state of the engine, the brakes, and the like are controlled to execute processing such as avoiding collision with an obstacle and maintaining a safe inter-vehicle distance with a preceding vehicle.

[0007] By the way, there are various obstacles in an actual traveling environment, and it is necessary to perform an accurate control according to the type of the obstacles. For this purpose, for example, whether the detected obstacle is a dangerous object to avoid a collision, an object on a road shoulder with a low danger of collision such as a guardrail or a sign, etc. It is necessary to accurately identify whether or not the vehicle is running.

However, in the above-mentioned radar device, although the number of obstacles, the distance to each obstacle, and the relative speed can be detected, it is not possible to identify what the obstacle is. Therefore, usually, when the relative speed with respect to the obstacle is substantially equal to the speed of the own vehicle, the obstacle is estimated to be an object on the road shoulder, and for such an object on the road shoulder, for example, Even if approaching within a preset risk interval, processing such as generating an alarm is not executed.

[0009]

However, in this case, there is a possibility that, for example, a vehicle or the like that is partially stopped on the roadway and stopped at the roadside may be recognized as a mounted object on the roadside. Yes, it was not necessarily a favorable response.

That is, at night or the like, since the driver's sense of distance becomes ambiguous, it is considered that a vehicle stopped on the road shoulder is more likely to collide than a traveling vehicle. It is highly desirable that such vehicles can be identified as dangerous obstacles that may cause a collision.

The present invention has been made in order to solve the above problems.
Provided are an obstacle detection system capable of accurately identifying types of obstacles, particularly obstacles such as collisions during traveling, and a radar device and a transponder suitable for constructing the obstacle detection system. The purpose is to:

[0012]

According to the first aspect of the present invention, there is provided an obstacle detection system which is transmitted from an obstacle detection unit of a radar apparatus to detect an obstacle. When the radar wave is received by the transponder, the transponder modulates and returns the received radar wave.

In the radar device, the obstacle detecting means detects an obstacle based on the received radar wave reception signal, and the return signal extracting means uses the transponder from the radar wave reception signal. The modulated return signal is extracted, and the obstacle specifying means specifies the transponder-mounted obstacle among the obstacles detected by the obstacle detecting means based on the extracted return signal.

Therefore, according to the obstacle detection system of the present invention, if the transponder is attached to an object having a risk of collision or the like in advance, the radar device is moving or stopped. Regardless of this, the object can always be reliably identified as a dangerous obstacle.

In particular, if a transponder is required to be mounted on each vehicle and the transponder is operated even when the vehicle is parked or stopped, a vehicle stopped on the road shoulder at night can be Recognizing that the vehicle is an object on the road without misidentifying it, avoiding approaching the vehicle or warning of the danger of collision, etc. Vehicle control can be performed.

The transponder is not mounted on a dangerous object, but is detected as an obstacle by the obstacle detecting means but has a low risk of collision or the like. It may be mounted on an installed object (for example, a guardrail or a sign) on a road shoulder. In this case, the radar apparatus may recognize an obstacle without a return signal as an obstacle having a risk of collision or the like, and perform various controls.

According to a seventh aspect of the present invention, the transponder is configured to be portable, so that the transponder can be carried by a pedestrian or other objects having a risk of collision (for example, the transponder is mounted for working on a road). Various types of collision accidents can be prevented beforehand by appropriately attaching the device to an object that is used or used).

The obstacle detecting means constituting the radar apparatus transmits a radar wave according to a transmission signal whose frequency is modulated in a triangular wave form, and receives the radar wave returned from the obstacle. Based on a beat signal that is a frequency component of a difference between both signals generated by mixing a signal and a local signal having a frequency equal to the transmission signal, at least one of a distance to the obstacle or a relative speed. You may comprise as what implement | achieves what is called FMCW system which detects one.

In this case, as described in claim 3, the transponder amplitude-modulates the received radar wave with a modulation signal whose frequency is greater than twice the frequency of the beat signal, and the return signal extraction means includes: A signal component in the vicinity of the frequency of the modulated signal may be extracted as a return signal modulated by the transponder from signal components generated by mixing the received signal and the local signal by the obstacle detection unit.

That is, the signal amplitude-modulated by the transponder has a sideband at a frequency (fr ± fc) shifted by the frequency fc of the modulated signal with the frequency fr of the received signal not subjected to amplitude modulation as the center. It will be. That is, the reception signal of the radar wave received by the radar device includes a component whose frequency is fr, fr ± fc.

The spectrum of the signal generated by mixing this signal with the transmission signal (frequency fs) in the radar apparatus is as shown in FIG. 4 when removing the high frequency components near the frequency fs + fr. , Frequency fb (=
| Fs−fr |), fc ± fb (= | fs− (fr ± f
c) |, where fb <fc) is included.

To ensure that the beat signal (frequency fb) used by the obstacle detection means and the return signal (frequency fc ± fb) to be extracted by the return signal extraction means can be reliably separated, It is necessary that fb <fc−fb, that is, 2fb <fc, so that both frequency components do not overlap.

It is desirable that the frequency fc of the modulated signal be about 10 times the frequency fb of the beat signal in order to more reliably identify the beat signal and the return signal. Further, the return signal extracted in this way is used by the obstacle specifying means as described in claim 4.
A second beat signal is generated by mixing a second local signal having the same frequency as the modulation signal, and a distance or a relative speed calculated based on the beat signal among obstacles detected by the obstacle detection means. May be identified as an obstacle equipped with a transponder, if the calculated value is based on the second beat signal.

That is, the return signal (frequency fc ± fb)
If the second local signal (frequency fc) is mixed, a second beat signal having the same frequency as the beat signal based on the simple reflected wave can be obtained. Therefore, the distance from the second beat signal to the obstacle equipped with the transponder Or relative speed.

Note that the beat signal is generated when the frequency of the second beat signal is directly compared with the frequency of the beat signal without obtaining the distance or relative speed from the second beat signal. May be specified as an obstacle equipped with a transponder.

By the way, the transponder used for constructing the obstacle detection system as described above is claimed in claim 8.
As described, an antenna that transmits and receives radar waves, an antenna connection unit connected to the antenna, a reception signal output unit that outputs only a signal input from the antenna connection unit, and an input signal from the antenna connection unit What is necessary is just to provide a circulator having a transmission signal input section that outputs only the signal, and a modulator that modulates an output signal from the reception signal output section and generates an input signal to the transmission signal input section.

That is, in the transponder thus configured, when the antenna receives a radar wave, the circulator to which the received signal is input from the antenna connection unit outputs the received signal only from the received signal output unit. Then, after the received signal is amplitude-modulated by the modulator, it is input to the transmission signal input section of the circulator,
Supplied to the antenna from the antenna connection part, by sending out as a radar wave using the same antenna as when receiving,
A return signal is returned by modulating the received signal in the direction in which the radar wave has been transmitted.

As described above, according to the transponder of the present invention, since the transponder has an extremely simple structure, it can be configured to be small and lightweight, and can be mounted without damaging the appearance of a vehicle or the like. The modulator constituting the transponder preferably has a signal amplification function of amplifying an input signal to the transmission signal input section.

In this case, the reception level of the return signal in the radar device increases, so that an obstacle on which the transponder is mounted can be reliably detected by the radar device.
Also, since the signal level is higher than the reception signal obtained by receiving a normal reflected wave, the reception signal has a harmonic component, and even when the frequency band of this harmonic component overlaps the frequency band of the return signal, The return signal can be reliably extracted.

As a method of amplifying the input signal to the transmission signal input unit, the output signal from the reception signal output unit may be amplified, or the modulation signal may be amplified by using a large power signal. Alternatively, the modulated signal may be amplified. The transponder is not limited to the above-described transponder, and a transmitting antenna and a receiving antenna may be separately provided, and the above-described obstacle detection system may be configured using a transponder configured without using a circulator.

On the other hand, a radar device used for constructing the obstacle detection system as described above is an obstacle detecting means for detecting an obstacle by transmitting and receiving radar waves, Return signal extraction means for extracting a return signal modulated by the transponder from the radar wave reception signal received by the detection means; and obstacle detection based on the return signal extracted by the return signal extraction means. Any means may be used as long as it includes obstacle specifying means for specifying an obstacle on which the transponder is mounted, among the obstacles detected by the means.

[0032]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of each component (radar device and transponder) of the on-board obstacle detection system of the present embodiment, and FIG. 2 is an explanatory diagram showing the use state of each component.

As shown in FIG. 1, the on-vehicle obstacle detection system according to the present embodiment transmits and receives radar waves to detect a distance and a relative speed to an obstacle.
And a transponder 40 that modulates and returns the radar wave when it is received. In particular, the radar device 10 includes a signal processing circuit unit 10a that performs signal processing such as transmitting and receiving radar waves, and a signal processing circuit 10a. The ECU 10b executes various controls based on data obtained by controlling the circuit unit 10a.

Then, as shown in FIG.
0 indicates that the signal processing circuit unit 10a is attached to the front of the vehicle and provided inside the vehicle so that the radar wave can be transmitted toward the front of the vehicle and can be received from the front of the vehicle. Connected to the ECU 10b via a signal line. On the other hand, the transponder 40 is mounted on the rear surface of the vehicle so as to receive radar waves from the rear of the vehicle and transmit the radar waves toward the rear of the vehicle.

Here, first, the transponder 40, which is one of the components of the on-board obstacle detection system of the present embodiment, is used.
Will be described. As shown in FIG. 1B, the transponder 40 includes a transmitting / receiving antenna 42 for transmitting / receiving a radar wave in a microwave band, and an oscillator 4 for generating a modulation signal Mc.
6 and the received signal SP supplied from the transmitting / receiving antenna 42
r is amplitude-modulated and amplified according to the modulation signal Mc,
A modulation amplifier 48 for generating a transmission signal SPs to be supplied to the transmission / reception antenna 42, an antenna connection end a to which the transmission / reception antenna 42 is connected, a reception signal output end o to which the input end of the modulation amplifier 48 is connected, and an output of the modulation amplifier 48 An input signal from the antenna connection terminal a is output only to the reception signal output terminal o, and an input signal from the transmission signal input terminal i is output only to the antenna connection terminal a. A circulator 44 is provided.

That is, the transponder 40 converts the radar wave reception signal SPr received by the transmission / reception antenna 42 into
The modulation amplifier 48 amplitude-modulates and amplifies with the modulation signal Mc of the frequency fc to generate a transmission signal SPs, and the transmission / reception antenna 42 transmits a radar wave according to the transmission signal SPs.

Next, a radar device 10 which is another component of the on-board obstacle detection system of the present embodiment will be described. Since the radar device 10 is obtained by adding a part of the configuration to the conventional radar device 110 described above, the same components are denoted by the same reference numerals, and the description thereof will be omitted. Will be described. However, LPF2
The beat signal extracted by No. 4 is represented by Sb1, and data obtained by converting the beat signal Sb1 by the AD converter 26 is represented by Db1.

That is, the signal processing circuit unit 10a of the radar device 10 in the present embodiment includes a voltage controlled oscillator 12, a DA converter 14, a directional coupler 16, a transmitting antenna 18, a receiving antenna 20, a mixer 22, an LPF 24, and an AD. Converter 2
6, a band-pass filter (BPF) 30 for extracting only a frequency component near the frequency fc of the modulation signal Mc generated by the oscillator 46 of the transponder 40 from the signal IF generated by the mixer 22; The oscillator 32 that generates the second local signal Lc having the same frequency fc as the signal Mc, and the signal IFm extracted by the BPF 30 include:
By mixing the second local signal Lc, these two signals IF
The second beat signal Sb2 composed of the frequency component of the difference between m and Lc
And an AD for converting the second beat signal Sb2 generated by the mixer 34 into digital data Db2.
And a converter 36.

It is to be noted that the bandwidth of the BPF 30 is such that when the maximum value of the frequency fb1 of the beat signal Sb1 is fbmax, the lower limit frequency is fc-fbmax or less, and the upper limit frequency is fc-fc.
+ Fbmax or more, that is, the frequency band fc−fbmax to fc +
It is assumed that the width is set to a value larger than fbmax.

That is, similarly to the conventional radar device 110, the signal processing circuit section 10a transmits and receives a radar wave modulated in a triangular waveform such that the frequency changes linearly, and mixes these transmitted and received signals. Beat signal Sb1 from IF
Is extracted, and the data Db1 obtained by AD conversion of the extracted
Supply to U10b.

In addition, in the signal processing circuit section 10 a, the BPF 30 extracts a frequency component near the frequency fc from the signal IF generated by the mixer 22, so that the return signal I amplitude-modulated by the transponder 40 is obtained.
Fm, and the mixer 34 outputs the extracted return signal IFm
The second beat signal Sb2 is generated by mixing the second beat signal Sb2 from the oscillator 32 with the second beat signal Sb2. The AD converter 36 converts the second beat signal Sb2 into digital data Db2 and supplies the digital data Db2 to the ECU 10b.

Next, the signal processing circuit section 10
a and the second beat signal S
Based on data Db1 and Db2 obtained by AD-converting b2, E
The obstacle detection processing executed by the CU 10b will be described with reference to the flowchart shown in FIG.

The ECU 10b starts transmitting the modulated data Dm to the D / A converter 14 and sets the A / D converter 2
6 and 36, every cycle of the triangular wave modulation signal M, that is, one set of the up modulation in which the frequency increases and the down modulation in which the frequency decreases, is completed. This process is started every time the data Db1 and Db2 are taken in.

Here, it is assumed that the transponder 40 is required to be mounted on the vehicle, and that the transponder 40 is always operating even when the vehicle is stopped. As shown in FIG. 3, when this process is started, first, in S110, the data Db1 of the beat signal Sb1 read from the AD converter 26 is subjected to FFT analysis.

In S120, all (here, n) peak frequency components are extracted from the spectrum of the beat signal Sb1 obtained as a result of the FFT analysis, and the peak frequency components are extracted based on the frequency of the extracted frequency components. For the generated targets (that is, obstacles that reflect radar waves, hereinafter referred to as reflection targets) G1 to Gn, the distance RGi and the relative speed VGi between the vehicle and the reflection target Gi (hereinafter, target data DGi and the Call).

In the following S130, the AD converter 3
The data Db2 of the second beat signal Sb2 read from S6 is subjected to FFT analysis in the same manner as in S110, and the subsequent S1
At 40, all (here, m) peak frequency components are extracted from the spectrum of the second beat signal Sb2 obtained as a result of the FFT analysis, and the peak frequency components are generated based on the frequency of the extracted frequency components. The distances RPj and the relative speed VP between the own vehicle and the modulation target Pj for the targets P1 to Pm (that is, those on which the transponder 40 is mounted, hereinafter referred to as modulation targets).
j (hereinafter collectively referred to as target data DPj).

Note that the modulation targets P1 to Pm always reflect radar waves and are considered to be detected as reflection targets G1 to Gn.
Becomes In subsequent S150, the number n of the extracted reflection targets is set as the upper limit value Cmax of the counter, and the count value k is set to 1. In subsequent S160,
The target data DGk of the reflection target Gk is the target data DP1 to DP of the modulation targets P1 to Pm.
It is determined whether or not any one of them matches m.

If there is a match, and the determination is affirmative, the process proceeds to S170 assuming that the transponder 40 is mounted on the reflection target Gk, and the speed of the own vehicle separately detected (hereinafter referred to as the own vehicle speed) is determined. ) Vr,
It is determined whether or not the relative speed VGk of the reflection target Gk matches.

If a negative determination is made in S170,
The process proceeds to S180, in which it is recognized that the reflection target Gk is a running vehicle, and proceeds to S230. On the other hand, if an affirmative determination is made, the process proceeds to S190, in which the reflection target Gk is recognized as a stopped vehicle. And proceed to S230.

At S160, the target data DGk of the reflection target Gk is converted to the modulation targets P1 to Pm.
Does not match any of the target data DP1 to DPm, and a negative determination is made, it is determined that the transponder 40 is not mounted on the reflection target Gk and S200 is performed.
Then, similarly to S170, it is determined whether the vehicle speed Vr matches the relative speed VGk of the reflection target Gk.

If a negative determination is made in S200,
The process proceeds to S210, in which the reflection target Gk is recognized as a moving object other than the vehicle, and the process proceeds to S230. On the other hand, if an affirmative determination is made, the process proceeds to S220, where the reflection target Gk is an object on the road shoulder. After recognizing, the process proceeds to S230.

In S230, the count value k is set to the upper limit value Cma.
It is determined whether or not it is smaller than x. If an affirmative determination is made, the process proceeds to S240, where the count value k is incremented, and the process returns to S160 to repeatedly execute the above-described processing.
On the other hand, when a negative determination is made in S230, that is, when the processing is completed for all the reflection targets G1 to Gn,
In S250, according to the recognition result of the obstacle type for each of the reflection targets G1 to Gn, an alarm is sounded, a brake or an engine state is controlled to avoid a collision, a safe inter-vehicle distance is maintained, and the like. After performing the processing, the processing ends.

In this embodiment, the voltage controlled oscillator 12, the DA converter 14, the directional coupler 16, the transmitting antenna 18, the receiving antenna 20, the mixer 22, the LPF 24,
The AD converter 26, and S110 and S120 correspond to obstacle detection means. Also, the BPF 30 corresponds to a return signal extracting means, and includes an oscillator 32, a mixer 34, an AD converter 36,
S130 to S240 correspond to the obstacle specifying means.

As described above, in the on-vehicle obstacle detection system according to the present embodiment, the transponder 40 for modulating and returning the radar wave is mounted on the rear surface of the vehicle, and the radar wave is used to forward the vehicle. The radar device 10 that detects an obstacle detects not only the reflection targets G1 to Gn that reflect radar waves but also the modulation targets P1 to Pm that mount the transponder 40 and return modulated radar waves, and compare the two. By doing so, from among the reflection targets (obstacles), the one on which the transponder 40 is mounted (that is, the vehicle) and the other (the other than the vehicle) are distinguished.

Therefore, according to the on-board obstacle detection system of this embodiment, for example, even if the vehicle is stopped on the road shoulder,
This does not cause the vehicle to be mistakenly recognized as an installed object on the roadside such as a sign or a guardrail, and control for dealing with a stopped vehicle can be reliably executed, so that traveling safety can be improved.

In the above-described embodiment, the processing has been described on the assumption that the transponder 40 is required to be mounted on all vehicles. However, if there is a vehicle on which the transponder 40 is not mounted, the above-described S220 is executed. , The reflection target Gk may be recognized as a moving object other than a vehicle or a vehicle without a transponder, and in S230, the target Gk may be recognized as an object on the road shoulder or a stopped vehicle without a transponder. .

In the above embodiment, the transponder 40
Is mounted on the rear surface of the vehicle, but if the directivity of the transmitting / receiving antenna 42 of the transponder 40 is wide, it may be installed, for example, on the roof of the vehicle. Further, in the above-described embodiment, the case where an obstacle in front of the vehicle is detected has been described. However, the present invention may be used in a case where an obstacle behind or on the side of the vehicle is detected.

Further, in the above-described embodiment, the transponder 40 is mounted on the vehicle. For example, the transponder 40 is mounted on a point on the road shoulder such as a sign or a guard rail where the object is easily reflected. A reflection target that does not match the target may be specified as a vehicle.

The transponder 40 is made portable so that it can be carried by pedestrians or other objects having a risk of collision (for example, objects placed or used for working on roads). Or the like may be appropriately attached.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a radar device and a transponder configuring an obstacle detection system according to an embodiment.

FIG. 2 is an explanatory diagram showing a schematic mounting position of a signal processing unit of a radar device and a transponder.

FIG. 3 is a flowchart showing the contents of processing executed by an ECU.

FIG. 4 is an explanatory diagram showing frequency components of a signal generated by a mixer that mixes a local signal with a received radar wave signal.

FIG. 5 is a block diagram illustrating a general configuration of a conventional radar device.

[Explanation of symbols]

10 radar apparatus 10a signal processing circuit section 1
0b: ECU 12: voltage-controlled oscillator 14: DA converter 1
6 directional coupler 18 transmission antenna 20 reception antenna 2
2, 34 mixer 24 low-pass filter (LPF) 30 band-pass filter (BPF) 26, 36 AD converter 32, 46 oscillator 4
0: transponder 42: transmitting / receiving antenna 44: circulator 4
8: Modulation amplifier a: Antenna connection end i: Transmission signal input end o
… Reception signal output terminal

Continued on the front page F term (reference) 5J070 AB19 AB24 AC02 AC06 AD02 AE01 AE20 AF03 AH14 AH25 AH31 AH35 AH39 AH40 AK14 BA01 BC16 BC37 BD03 BF02 BF03 BF10 BF12 BF16 BF20

Claims (10)

[Claims] 1. A radar device having an obstacle detecting means for detecting an obstacle by transmitting and receiving radar waves, and a transponder formed separately from the radar device and modulating and returning a received radar wave. In the radar device, a return signal extraction unit that extracts a return signal modulated by the transponder from a reception signal of a radar wave received by the obstacle detection unit; An obstacle detection system, comprising: an obstacle identification unit that identifies an obstacle equipped with the transponder among obstacles detected by the obstacle detection unit based on the returned signal. 2. The obstacle detecting means transmits a radar wave according to a transmission signal whose frequency is modulated in a triangular wave form, and receives a radar wave returned from the obstacle and a local signal having a frequency equal to the transmission signal. And detecting at least one of a distance to the obstacle and a relative speed based on a beat signal which is a frequency component of a difference between the two signals generated by mixing the two signals. Obstacle detection system as described. 3. The obstacle detection system according to claim 2, wherein the transponder amplitude-modulates a received radar wave with a modulation signal having a component whose frequency is larger than twice the frequency of the beat signal, and the return signal. Extracting means for extracting, from the signal components generated by mixing the received signal and the local signal by the obstacle detecting means, a signal component near the frequency of the modulated signal as the return signal; An obstacle detection system characterized by the following. 4. The obstacle detection system according to claim 3, wherein the obstacle identification unit adds a second local signal having the same frequency as the modulation signal to the return signal extracted by the return signal extraction unit. A second beat signal is generated by mixing, and among obstacles detected by the obstacle detection means, a distance and a relative speed calculated based on the beat signal are calculated based on the second beat signal. An obstacle detection system, characterized in that an object that matches the value is identified as an obstacle equipped with the transponder. 5. The obstacle detection system according to claim 1, wherein the transponder is mounted on a vehicle. 6. The transponder according to claim 1, wherein said transponder is detected as an obstacle by said obstacle detecting means, and is mounted on an object on a road shoulder having a low risk of collision. Obstacle detection system according to the above. 7. The obstacle detection system according to claim 1, wherein the transponder is configured to be portable. 8. An antenna for transmitting / receiving a radar wave, an antenna connection unit connected to the antenna, a reception signal output unit for outputting only a signal input from the antenna connection unit, and an input signal transmitted from the antenna connection unit. A circulator having a transmission signal input section that outputs only the signal; and a modulator that modulates an output signal from the reception signal output section to generate an input signal to the transmission signal input section. transponder. 9. The transponder according to claim 8, wherein the modulator has a signal amplification function of amplifying an input signal to the transmission signal input unit. 10. A transponder according to claim 8 or 9, wherein: an obstacle detecting means for detecting an obstacle by transmitting / receiving a radar wave; and a radar wave receiving signal received by said obstacle detecting means. Return signal extraction means for extracting a modulated return signal; and the transponder is mounted on obstacles detected by the obstacle detection means based on the return signal extracted by the return signal extraction means. A radar device comprising: an obstacle specifying unit that specifies an obstacle.