JP3421058B2 - Automotive radar equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an on-vehicle radar device for the purpose of collision prevention or forward monitoring.

BACKGROUND ART FIG. 1 is a conventional vehicle-mounted device shown in a document (Konagawa, Koshikawa, “Millimeter-wave radar sensor with simple communication function”, IEICE Electronics Society Conference, C-2-72, PP.107. September 1997). FIG. 2 is a circuit block diagram showing a configuration of a radar sensor in the radar device, and FIG. 2 is a waveform diagram showing a mode switching signal in the on-vehicle radar device.

In FIG. 1, 1 is a radar sensor, 2 is a VCO (voltage controlled oscillator), 3 is a transmitting antenna connected to the VCO2, 5 is a receiving antenna, 6 is a directional coupler, 7 is the receiving antenna 5 and the above. A mixer connected to the directional coupler 6, and 8 and 9 are BPFs connected to the mixer 7, respectively.
(Band pass filter) and LPF (Low pass filter), 1
0 is a video amplifier connected to LPF9, 11 is a video amplifier connected to BPF8, and 12 and 13 are a mode selection circuit and an ASK modulator connected to VCO2.

  Next, the operation will be described.

The radar sensor 1 operates in two modes, a radar mode and a communication mode, according to the mode switching signal shown in FIG. Although not shown in the figure in the communication mode, the radar sensor 1
It communicates with the communication device mounted on the rear part of the front vehicle that travels in front of the vehicle equipped with.

First, the operation in the radar mode will be described. VCO2
The carrier wave is a transmission signal FM-modulated by the triangular waveform of the radar mode output from the mode selection circuit 12, and is transmitted to the transmission antenna 3 and the mixer 7 via the directional coupler 6. The transmission signal radiated from the transmission antenna 3 arrives at the forward rate, and its reflected wave is received by the reception antenna 5. At this time, the reflected wave is affected by the Doppler shift according to the relative speed between the own vehicle and the preceding vehicle on the frequency axis,
Further, on the time axis, when the transmission signal is used as a reference, it is received as a signal delayed by a delay time corresponding to the distance between the own vehicle and the preceding vehicle.

The received signal is mixed with the transmission frequency by the mixer 7, and a beat signal corresponding to up and down of the triangular waveform is output. Although this beat signal varies depending on the system, it has a frequency component of approximately 100 KHz or less. For this reason,
Only this beat signal can be extracted as a radar mode signal by LPF9.

Next, the communication mode will be described. In the communication mode, the mode switching signal has a constant voltage waveform as shown in FIG. At this time, depending on the modulation signal (data information), ASK
The modulator 13 ASK-modulates the carrier of the VCO2. A
The SK-modulated carrier wave is a transmission signal having data information and is transmitted through the directional coupler 6 to the transmission antenna 3 and the mixer 7.
Sent to. Although not shown in the figure, the transmission signal radiated from the transmission antenna 3 is received by the reception antenna of the communication device mounted in the vehicle ahead and the envelope is detected.

In addition, the radar sensor 1 receives data information from the communication device.
In the case of sending to the device, data information is sent from the transmitting antenna as a PSK modulated signal using a 450 KHz subcarrier in the communication device. In the radar sensor 1, a signal obtained by adding the Doppler shift to this modulated signal is received by the receiving antenna 5 and then mixed with the transmission signal by the mixer 7,
The modulation signal component and the Doppler frequency component of the 450KHz subcarrier can be obtained. Of these, only the modulation signal component of the 450 KHz subcarrier is extracted by the BPF 8 as a communication mode signal.

Therefore, the radar sensor 1 can obtain the radar mode signal and the communication mode signal by switching the observation time according to each mode of the mode switching signal, and the communication device mounted on the vehicle in front can communicate with the radar sensor 1 only in the communication mode. Can communicate. In other words, while operating as an FM-CW radar that fulfills the radar function only with the vehicle equipped with the radar sensor 1, two-way communication is possible by both the table equipped with the radar sensor 1 and the forward vehicle equipped with the communication device by time division. It acts as a vehicle-mounted radar device having a communication function.

Since the conventional on-vehicle radar device is configured as described above, the frequency components of the reflected wave from the vehicle in front and the reflected wave from other stationary objects (for example, a guardrail or a falling object on the road) are Doppler frequency components. Except for, the same transmission frequency (frequency of carrier wave) component is included. Therefore, the instantaneous radar mode signal (beat signal) finally obtained by the radar sensor cannot distinguish the targets of the preceding vehicle and other stationary objects, and the speed, distance, and It is necessary to distinguish from changes in angle information (beam scan angle or handle angle). Therefore, the processing using the target information (distance, speed, angle) on the time axis becomes complicated, and in some cases there is a delay in the execution of processing to avoid collision (warning the driver, automatic deceleration, automatic braking). There is a problem that arises.

Further, in actuality, there is a leak of radio waves from the transmitting antenna to the receiving antenna in the radar sensor, or a leak of radio waves to the receiving side inside the radar sensor other than the antenna, so that the relative speed is set to 0 as the radar mode signal. There is a corresponding DC component. Therefore, there is a problem peculiar to the FM-CW radar that a false image of the target that depends on this DC component is visible.

Also, if the oncoming vehicle traveling in the opposite lane is equipped with the same radar sensor, the polarization of the transmitting / receiving antenna of the radar sensor should be set at an angle of 45 degrees in order to avoid direct wave interference from this oncoming vehicle to the own vehicle. An antenna having a linearly polarized wave or a circularly polarized wave must be used, and depending on the antenna system (for example, a traveling wave feed slot array antenna), the improvement of the polarization isolation hinders the improvement of the antenna efficiency. Therefore, either relax the maximum detection distance specifications, or
There is also a problem that the S / N of the receiver must be improved (cost increase) in order to prevent this.

The present invention has been made to solve the above problems, and obtains a vehicle-mounted radar device that does not generate a false image due to leakage of a DC component, and polarizes interference caused by a direct wave from an oncoming vehicle. An object of the present invention is to obtain a vehicle-mounted radar device that can be avoided regardless of isolation.

Another object of the present invention is to obtain a vehicle-mounted radar device that can remove a beat signal corresponding to a stationary object by H / W without using signal processing and can extract a beat signal for a vehicle ahead.

DISCLOSURE OF THE INVENTION The in-vehicle radar device of the present invention uses a subcarrier for a transmission signal obtained by FM-modulating a transmission frequency with a triangular waveform or a transmission signal composed of a modulation signal having the above-mentioned triangular waveform and an unmodulated signal having a constant voltage waveform. Waveform addition means for adding a modulation waveform obtained by modulating the existing modulated signal (data information such as ID code), and the relay wave after mixing the received signal with the signal in the previous stage that is modulated with the modulated signal using the subcarrier And a radar sensor having a beat signal extracting means for obtaining a beat signal for With this configuration, it is possible to identify whether the extracted beat signal is for the transmission signal transmitted from the radar sensor of another vehicle (for example, a vehicle traveling in the adjacent lane) or for the transmission signal of the own vehicle. The device can be obtained.

Further, the on-vehicle radar device of the present invention comprises two types of beat signals for a reflected wave and a relay wave from a vehicle in front after mixing the reception output of the radar sensor with a signal in the preceding stage which is modulated with a modulation signal using a subcarrier. It is characterized by having two kinds of beat signal extraction means for obtaining With this configuration, even when a plurality of vehicles equipped with the same radar sensor travel, vehicles that do not operate due to a repeater failure, vehicles that do not have a repeater, and various stationary objects (guardrails and fall It is possible to obtain a vehicle-mounted radar device that can extract a beat signal corresponding to a transmission signal transmitted from the radar sensor of the own vehicle, out of the beat signal corresponding to the reflected wave of the object).

Further, in the in-vehicle radar device of the present invention, the repeater mounted on the rear part of the vehicle ahead is demodulated by the demodulation means for demodulating the first data information from the received signal and the first data information in the received signal. It is characterized by further comprising: a waveform forming means for waveform-shaping a portion of the unmodulated signal into a non-modulated signal; and a modulating means for modulating a part of the unmodulated signal with second data information using a subcarrier. With this configuration, it is possible to obtain a vehicle-mounted radar device capable of bidirectional communication between the host vehicle and the vehicle in front, that is, having both the inter-vehicle communication function for the front and the rear of the vehicle and the collision prevention function. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit block diagram showing a configuration of a radar sensor showing an example of a conventional radar device, FIG. 2 is a waveform diagram of a mode switching signal in the radar device, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a circuit block diagram showing a configuration of an on-vehicle radar device according to the first embodiment, FIG. 4 is a waveform diagram of a transmission signal in the first embodiment of the present invention, and FIG. 5 is a second embodiment of the present invention.
FIG. 6 is a circuit block diagram of a radar sensor constituting the on-vehicle radar device, FIG. 6 is a waveform diagram of a transmission signal in the on-vehicle radar device according to the third embodiment of the present invention, and FIG. 7 is an embodiment of the present invention. 3 is a circuit block diagram of a radar sensor which constitutes the on-vehicle radar device shown in FIG. 3, FIG. 8 is a circuit block diagram of the radar sensor which constitutes the on-vehicle radar device which shows Embodiment 4 of the present invention, and FIG. FIG. 10 is a waveform diagram of a transmission signal in the on-vehicle radar device showing the fifth embodiment of the present invention, and FIG. 10 is a circuit block diagram of a repeater constituting the on-vehicle radar device showing the fifth embodiment of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to describe the present invention in more detail, the best mode for carrying out the present invention will be described with reference to the accompanying drawings.

Embodiment 1 FIG. 3 is a configuration diagram of a vehicle-mounted radar device according to Embodiment 1 of the present invention, and FIG. 4 is a waveform diagram showing a transmission signal in Embodiment 1. In FIG. 3, 21a is a radar sensor mounted in the vehicle, 22 is an FM modulator in the radar sensor 21a, 23a is a VCO whose voltage is controlled by the FM modulator 22, 24a is a transmitting antenna, 25a is a receiving antenna, 2
6 is a directional coupler connected between the above VCO 23a and the transmission antenna 24a, 27a and 27b are mixers, 28a is a BPF connected to the output side of the mixer 27a, and 29a is the mixer 27b.
Is a local oscillator connected to, and these constitute a radar sensor 21a. Where FM modulator 22, VCO23
a, transmitting means by the directional coupler 26, receiving means by the directional coupler 26, mixer 27a, BPF28a, also,
The mixer 27b and the local oscillator 29a respectively constitute beat signal extracting means.

Reference numeral 30a is a repeater mounted in the rear part of the front vehicle traveling in front of the own vehicle, and has a reception antenna 25b, a local oscillator 29b, a mixer 27c, and a transmission antenna 24b. Reference numeral 31 is a reflected wave transmitted from the transmitting antenna 24a and reflected by a vehicle ahead, and 32 is a relay wave transmitted from the transmitting antenna 24a, passing through the relay 30a, and arriving at the receiving antenna 25a. Fourth
In the figure, 33a and 34a are a modulated signal and a non-modulated signal output from the VCO 23a, respectively, and 35a is a transmission signal composed of the modulated signal 33a and the unmodulated signal 34a.

Next, the operation of this on-vehicle radar device will be described.

The modulation waveform formed by the FM modulator 22 may be a triangular waveform or a triangular waveform + constant voltage waveform. Here, a case where the VCO 23a is voltage-controlled by the latter triangular waveform + constant voltage waveform will be described. In this case, the output from the VCO 23a is the transmission signal composed of the modulated signal 33a and the unmodulated signal 34a.
35a. Here, the modulation signal 33a is an FM modulation signal whose center frequency is f0 and whose frequency changes (up and down) within the band of the radar sensor 21a.

To simplify the expression in the following description, the frequency of the transmission signal 35a is typically expressed using f0. This transmitted signal 35
a is a transmission antenna 24a and a mixer via a directional coupler 26.
Supplied to 27a. The transmission signal 35a radiated from the transmission antenna 24a includes a reflected wave 31 reflected by a vehicle traveling in front, an output of the local oscillator 29b (frequency foff) received by the reception antenna 25b of the repeater 30a, and a mixer 27c.
Is divided into two, that is, the relay wave 32 that is mixed by and transmitted from the transmitting antenna 24b, and both are received by the receiving antenna 25a of the vehicle.

At this time, if the relative speed of the own vehicle equipped with the radar sensor 21a and the preceding vehicle equipped with the repeater 30a is not 0, the reflected wave is affected by the Doppler shift depending on the relative speed. The frequency of f0 + fd, and the frequency of Shin longitudinal wave 32 is f0 + fd + foff. Here, fd is a Doppler frequency due to Doppler shift, and in the case of an on-vehicle radar device, it is a frequency component of approximately 100 KHz or less. The reflected wave 31 and the relay wave 32 received by the reception antenna 25a are mixed by the transmission signal 35a (frequency component f0) and the mixer 27a, and two groups of beat signals of the frequency component fd for the reflected wave 31 and the frequency component fd + foff for the relay wave 32 are mixed. Is obtained.

Now, if the frequency foff of the local oscillator 29b in the relay wave 32 is set to a frequency sufficiently higher than the Doppler frequency component fd, only the beat signal of the frequency component fd + foff for the frequency offset relay wave 32 of these two groups of beat signals is generated. It can be taken out from BPF28a. Further, this beat signal has the same frequency foff as the local oscillator 29b of the repeater 30a.
The Doppler frequency component fd corresponding to the relay wave 32 can be extracted by mixing the signal of the local oscillator 29a with the mixer 27b.

To be precise, in the mixer 27a, two kinds of beat signals (up and down) corresponding to the difference between the triangular waveform modulation signal portions.
Since the Doppler frequency component corresponding to the difference between the frequency component of and the unmodulated signal portion of the constant voltage waveform is extracted, the output of the mixer 27b is the frequency component of the above two types of beat signals and the Doppler frequency component (however, the Doppler frequency component is It can be calculated from the above two types of beat signals).

Therefore, as a vehicle-mounted radar device that can know the distance and the relative speed between the forward vehicle equipped with the repeater 30a and the own vehicle from these frequency components, and prevent or avoid the collision between the own vehicle and the preceding vehicle. To work.

In the case of the conventional vehicle-mounted radar device as shown in FIG. 1, the only beat signal finally obtained is the beat signal corresponding to the reflected wave 31 of the vehicle ahead, and the radar sensor 21a always leaks the DC component to obtain the speed. 0 object, this DC
A false image is detected due to the combination of the component and the beat signal.

Further, if the DC component is cut by signal processing to avoid this problem, the forward vehicle cannot be detected when the own vehicle and the forward vehicle are moving at the same speed. Therefore, time-series data such as distance, relative velocity, or angle must be correlated, and a considerable amount of processing time is required to remove false images by signal processing.
It is fatal for collision prevention radars that compete for msec.

On the other hand, according to the in-vehicle radar device of the first embodiment, the DC component due to the leak is removed by the BPF 28a, so that the problem of the false image due to the leak of the DC component can be solved. Also, since the finally obtained beat signal is for the relay wave 32 that has passed through the repeater 30a mounted on the front vehicle, it is possible to remove the beat signal due to a stationary object other than the front vehicle (for example, a guardrail or a signboard). As a result, it is possible to reliably detect a vehicle ahead even when traveling on a curve.

Furthermore, since the repeater 30a offsets the frequency of the received signal and returns it to the radar sensor 21a, the beat signal finally obtained is the same even if the polarizations of the radar sensors of the own vehicle and the oncoming vehicle are the same polarization. Designed for the transmitting antennas 24a and 24b and the receiving antennas 25a and 25b because it is for a vehicle ahead and can avoid interference by direct waves of oncoming vehicles and does not need to limit polarization to diagonal 45 degree polarization or circular polarization. The effect that the degree of freedom of can be improved can also be obtained.

Embodiment 2. FIG. 5 is a configuration diagram of a radar sensor 21b which constitutes an on-vehicle radar device according to Embodiment 2 of the present invention. In the second embodiment, the output of the mixer 27a in the radar sensor 21a of the on-vehicle radar device according to the first embodiment shown in FIG. 3 is divided into two, one is the BPF 28a and the other is the LPF.
It is configured to supply to 36a. Where BPF28a
Similarly to the radar sensor 21a of the first embodiment, the output of is supplied to the mixer 27b together with the output of the local oscillator 29a. The repeater (not shown) in the second embodiment is similar to the repeater 30a shown in FIG. 3, and the transmission signal is similar to the transmission signal 35a shown in FIG.

As described above, according to the on-vehicle radar device of the second embodiment, the reflected wave 31 and the relay wave 32, which are the outputs of the mixer 27a as the two kinds of beat signal extraction means, are divided into two.
Since the beat signals of the group are filtered by the BPF 28a and LPF 36a, the beat signal (frequency component f
d) can be extracted from the LPF 36a, and the beat signal (frequency component fd + foff) for the relay wave 32 can be extracted from the BPF 28a.

Further, similar to the first embodiment, the beat signal extracted by the BPF 28a is mixed with the output of the local oscillator 29a (frequency component foff) by the mixer 27b to obtain the beat signal (frequency component fd) for the relay wave 32. You can Therefore, in addition to the beat signal for the relay wave 32, a beat signal for the reflected wave 31 can be obtained, and the relative speed and distance between the own vehicle and the front vehicle can be obtained even when the preceding vehicle has failed and the repeater 30a is not operating. In addition to being able to calculate, a vehicle other than the vehicle in front of the vehicle not equipped with the relay 30a, a motorcycle, a bicycle, and various stationary objects (guardrails and falling objects) can be detected.

Embodiment 3 FIG. 6 is a waveform diagram of a transmission signal in an in-vehicle radar device according to Embodiment 3 of the present invention, and FIG. 7 is a radar sensor 21 in an in-vehicle radar device according to Embodiment 3 of the present invention. It is a block diagram of. In the third embodiment, in addition to the modulated signal 33a and the non-modulated signal 34b in the transmission signal 35a of the vehicle-mounted radar device according to the first embodiment shown in FIG. The modulation signal 33b obtained by modulating the transmission signal 35b is provided, and the transmission signal 35b is transmitted to the transmission antenna of the radar sensor 21c.
The signal is transmitted from 24a, and the reflected wave 31 and the relay wave 32 are received by the receiving antenna 25a.

In addition, in the radar sensor 21c, the transmission system has a modulator 37a between the output of the directional coupler 26 and the input of the transmission antenna 24a.
The modulator 37a is controlled by the timing signal 39 from the FM modulator 22, and the transmission information 35a formed by the VCO 23a is generated by the data information 38 using the subcarrier (frequency component fsc) (see FIG. 4). ), A modulated signal 33b is provided by modulating a part of the unmodulated signal 34a (for example, PSK modulation)
This is a configuration for generating 35b.

The receiving system supplies the output of the mixer 27a to the BPF 28a,
The output of this BPF 28a and the output of the local oscillator 29a are mixed with the mixer 27b.
And mix the output of this mixer 27b with LPF36b and BPF.
It is configured to supply to 28b. The repeater (not shown) in the third embodiment is the repeater 30a shown in FIG. 3, and the output of the VCO 23a is the transmission signal 3 shown in FIG.
Similar to 5a.

As described above, according to the on-vehicle radar device of the third embodiment, the modulated signal 33a used for radar is used.
In addition to the unmodulated signal 34b, the vehicle data information (for example, ID
Transmission signal 3 consisting of a modulated signal 33b having a code etc.)
5b is transmitted from the transmitting antenna 24a of the radar sensor 21c, and the reflected signal 31 and the relay wave 32 are received by the receiving antenna 25a, and then the mixer 27a supplies the modulated signal 33a and the non-modulated signal 34a from the directional coupler 26. Transmitted signal consisting of 35a
In order to mix with the signal of (frequency component f0), the mixer 27a outputs the beat signal (frequency component fsc + fd) and the relay wave 32 for the reflected wave 31 including the data information (frequency component fsc) using the subcarrier. A beat signal (frequency component fsc + fd + foff) is obtained.

For the beat signals of these two groups, only the beat signal for the relay wave 32 can be taken out by passing through the BPF 28a, and further, after being mixed with the output (frequency component foff) of the local oscillator 29a by the mixer 27b, LPF 36b and BPF 2 are mixed.
By applying the filter at 8b, the beat signal (frequency component fd) and the data information (frequency component fsc) for the relay wave 32 can be separated and extracted.

Therefore, it is determined whether the beat signal detected by the radar sensor 21c corresponds to the relay wave 32 of the transmission signal 35b transmitted from the transmission antenna 24a of the own vehicle and the extracted data information (ID code, etc.) It becomes possible to judge by the result of comparison with the car ID code etc.). That is, whether the extracted beat signal is the relay wave 32 for the transmission signal 35b transmitted from the radar sensor 21c of another vehicle (for example, a vehicle traveling in the adjacent lane), or the relay wave 32 for the transmission signal 35b of the own vehicle The effect that can be identified whether it is a thing is obtained.

Fourth Embodiment FIG. 8 is a configuration diagram of a radar sensor 21d in a vehicle-mounted radar device according to a fourth embodiment of the present invention. In the fourth embodiment, the output of the mixer 27a in the radar sensor 21c of the vehicle-mounted radar device according to the third embodiment shown in FIG. 7 is divided into two, one of which is the BPF 28a and the other is the LPF 36a.
The output of the LPF36a is further configured to supply
It is configured to supply to 36c and BPF28c.

In addition, the repeater in this Embodiment 4 (illustration is omitted)
The output of the repeater 30a and the VCO 23a shown in FIG. 3 is the same as the transmission signal 35a shown in FIG. 4, and the output of the modulator 37a is the same as the transmission signal 35b shown in FIG.

As described above, according to the vehicle-mounted radar device of the fourth embodiment, the two groups of beat signals for the reflected wave 31 and the relay wave 32, which are the output of the mixer 27a, are filtered by the BPF 28a and the LPF 36a. The beat signal for the reflected wave 31 (frequency component fsc + fd) is from the LPF 36a, and the beat signal for the relay wave 32 (frequency component fsc + fd + foff)
Can be extracted from BPF28a. Relay wave extracted by the above BPF28a
Similarly to the third embodiment, the beat signal for 32 is mixed with the output of the local oscillator 29a (frequency component foff) by the mixer 27b and then filtered by the LPF 36b and the BPF 28b to obtain a beat signal for the relay wave 32 (frequency component fd). Data information (frequency component fsc) can be separated and extracted.

Further, the beat signal (frequency component fsc + fd) for the reflected wave 31 extracted by the LPF 36a is filtered by the LPF 36c and the BPF 28c to separate the beat signal (frequency component fd) and the data information (frequency component fsc) for the reflected wave 31. Can be extracted.

Therefore, even when a vehicle equipped with the same radar sensor 21d as the own vehicle is traveling in the adjacent lane, for example, the beat signals for the reflected wave 31 and the relay wave 32 from the preceding vehicle are transmitted from the own vehicle's radar sensor 21d. It is possible to obtain an effect of distinguishing whether it is for the transmitted transmission signal 35b or whether it is from another vehicle equipped with the radar sensor 21d other than the own vehicle by comparing with the extracted data information of the own vehicle. Therefore, even when a plurality of vehicles equipped with the same radar sensor 21d travel, it is possible to reliably detect the beat signal for both the reflected wave 31 and the relay wave 32 of the transmission signal 35b transmitted from the radar sensor 21a of the vehicle. Is obtained.

Fifth Embodiment FIG. 9 is a waveform diagram of a transmission signal in a vehicle-mounted radar device according to a fifth embodiment of the present invention, and FIG. 10 is a configuration of a repeater in the vehicle-mounted radar device according to the fifth embodiment. It is a block diagram which shows. In the fifth embodiment, in the transmission signal 35b of the in-vehicle radar device according to the third embodiment shown in FIG. 6, the modulated signal 33b having the data information (for example, ID code) of the own vehicle is converted into the data of the own vehicle. Information (eg ID code) and other vehicle data information (eg ID
A modulated signal 33c having a code) and a transmission signal 35c.

Further, the repeater 30b is connected to the transmitting antenna 24b and the receiving antenna 25.
b, a mixer 27c and a local oscillator 29b, a demodulator 40 as demodulating means, a synchronizing circuit 41, and a modulator 37 as modulating means.
b and a signal processing section 43 as a waveform shaping means. The radar sensor according to the fifth embodiment is the radar sensor 21 shown in FIG. 7 and FIG.
Similar to c and 21d.

As described above, according to the in-vehicle radar device of this embodiment, the modulation signal 33c having the data information (dummy data) of the other vehicle in addition to the data information of the own vehicle (for example, the ID code) is provided. The transmitted signal 35c is sent to the radar sensor 21c (Fig. 7) or 21d (Fig. 8) of the vehicle.
Transmitting from 24a, receiving antenna 25b of repeater 30b of the vehicle ahead
After reception by the demodulator 40, a signal notifying the start and end of detection of the data information storage portion is input to the demodulator 40 in the synchronizing circuit 41, and the data information of the received signal is demodulated in synchronization with this signal 42.
Since the signal is sent to the signal processing unit 43 as, the ID code of the vehicle equipped with the radar sensor 21c or 21d (own vehicle) stored in the data information part of the own vehicle and various communication data can be received by the preceding vehicle. .

Further, in the preceding vehicle, the signal processing unit 43 stores the ID code and various communication data in the data information portion 33c of the conversion rate, and adds the received data information of the own vehicle to the modulated data 44 using the subcarrier. After being modulated by the modulator 37b (for example, PSK modulation), it is mixed with the output (frequency component foff) of the local oscillator 29b by the mixer 27c, and the frequency is offset and transmitted from the transmission antenna 24b. The ID code and various communication data can be communicated to the vehicle equipped with the radar sensor 21c or 21d.

Here, it is assumed that the modulator 37b temporarily changes the modulated signal 33c portion in the received signal into a non-modulated signal and then modulates this unmodulated signal portion with the modulated data 44. Therefore, it is possible to obtain an on-vehicle radar device capable of bidirectional communication between the own vehicle and the front desk. That is, it is possible to obtain the effect of being able to obtain the on-vehicle radar device having both the inter-vehicle communication function for the front and the rear of the own vehicle and the collision prevention function.

Here, the radar sensors 21a to 21d of the on-vehicle radar device in the above first to fifth embodiments have been described as the homodyne system, but the homodyne system and the heterodyne system having other configurations may be used.

Further, the radar sensors 21a to 21d and the repeaters 30a and 30b of the on-vehicle radar device according to the above-described first to fifth embodiments have amplifiers and the like removed for simplification of description, but they are provided. Is also good.

INDUSTRIAL APPLICABILITY As described above, the vehicle-mounted radar device according to the present invention includes a radar sensor that transmits and receives an FM modulated signal to extract a beat signal, and a frequency offset after receiving the FM modulated signal. Since it is configured with a repeater that transmits as a relay wave, it does not detect false images that depend on DC component leakage in radar sensors, and avoids interference from direct waves from oncoming vehicles regardless of polarization isolation. The beat signal for a stationary object can be removed.

Front page continuation (72) Inventor Shinichi Sato Marunouchi 2-3-3, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Tetsuo Haruyama 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (56) References JP-A-6-313795 (JP, A) JP-A-4-236388 (JP, A) Special Table Sho 63-501981 (JP, A) Millimeter-wave radar sensor with simple communication function, Kenichi Konno , Shoichi Koshikawa, 1997 IEICE Electronics Society Conference Proceedings 1, Japan, The Institute of Electronics, Information and Communication Engineers, August 13, 1997, C-2-72, 107 (58) Fields investigated ( Int.Cl. ⁷ , DB name) G01S ^7/ 00-7/42 G01S 13/00-13/95

Claims (3)

(57) [Claims] 1. A transmitting means for transmitting from a transmitting antenna a transmitting signal composed of an FM modulated signal whose transmitting frequency changes in a triangular wave form, or a transmitting signal composed of the FM modulated signal and an unmodulated signal of a constant frequency, and a receiving antenna. The radar sensor is provided with a receiving unit that obtains a plurality of beat signals by mixing the received signal received with the transmission signal, and the transmission wave from the vehicle equipped with the radar sensor is received by the reception antenna. The frequency of the received signal, the repeater mounted on the forward vehicle equipped with a transmitting means for transmitting as a relay wave from the transmitting antenna after offsetting in the band receivable by the radar sensor, the transmission signal in the radar sensor, A transmission signal consisting of an FM modulation signal whose transmission frequency changes in a triangular waveform, or consisting of the above FM modulation signal and an unmodulated signal of a constant frequency The received signal is a transmission signal having a modulation waveform obtained by modulating with a modulation signal using subcarriers, and the reception output of the radar sensor is mixed with the signal at the previous stage where it is modulated with the modulation signal using the subcarriers. An on-vehicle radar device comprising a beat signal extracting means for obtaining a beat signal corresponding to a relay wave. 2. A subcarrier is used as a transmission signal of a radar sensor, which is composed of an FM modulation signal whose transmission frequency changes in a triangular wave, or a transmission signal which is composed of the FM modulation signal and an unmodulated signal of a constant frequency. The reflected signal from the preceding vehicle, etc., after being mixed with the signal in the previous stage where the received signal in the radar sensor is modulated by the modulated signal using the subcarrier 2. The on-vehicle radar device according to claim 1, further comprising: two kinds of beat signal extracting means for obtaining two kinds of beat signals for the relay wave. 3. A demodulator for demodulating first data information by a demodulator from a reception signal obtained by receiving a repeater mounted on a vehicle ahead by a reception antenna, and first data information in the reception signal. A repeater comprising waveform shaping means for shaping the modulated part into an unmodulated signal and modulating means for modulating a part of the unmodulated signal with a modulated signal using subcarriers. The in-vehicle radar device according to claim 2.