JP5396052B2 - Radar transceiver - Google Patents

Description

  The present invention provides a radar transmission antenna that transmits a millimeter wave to a predetermined area, a radar reflector that reflects the transmitted millimeter wave, a millimeter wave from the radar reflector as a reference signal, and a reflection from within the area. The present invention relates to a radar transceiver including a radar receiving antenna for receiving a wave, and monitoring means for monitoring radar performance from a received signal.

  In recent years, with regard to improving vehicle safety, a radar device is installed on the front of the vehicle to transmit millimeter waves to the preceding vehicle and receive the reflected wave to obtain the relative position and relative speed with respect to the preceding vehicle for rear-end collision. There are known rear-end collision prevention systems and the like. Here, the shape of the vehicle is various, and the reflected wave is largely reflected from a target having a large reflection cross section (RCS). The higher the level of the reflected wave, the easier the relative position and relative speed of the target. Therefore, for example, Patent Document 1 discloses three or two surfaces that reflect millimeter waves in the incident direction in order to increase the RCS. The thing which provides a corner reflector in the rear surface of a vehicle is disclosed.

  In such a radar apparatus, an FMCW (Frequency Modulated-Continuous Wave) type radar is used. FMCW radar system modulates and transmits a millimeter-wave oscillation source with a triangular wave, and mixes a part of the received wave and the transmitted wave reflected from the target, so that the signal of the distance to the target and the relative velocity The beat signal including the component is obtained, and the distance to the target and the relative speed are obtained from the bead signal.

  In addition, as an application example other than a vehicle, there is an obstacle detection device that detects a car or a pedestrian on a railroad crossing road on which a train travels. Conventionally, obstacle detection on a railroad crossing, for example, using laser sensors, infrared sensors, optical sensors with visible cameras, ultrasonic sensors, etc., is susceptible to changes in weather conditions such as rain and snow There was a problem.

  The obstacle detection device disclosed in Patent Document 2 includes a reflecting object observation unit that irradiates a millimeter wave on a railroad crossing to receive reflected waves from a plurality of reflectors and observes the distance to each reflector and the reflection intensity, and a railroad crossing control control. Receives a signal from the device, detects the presence of an obstacle from the distance to the reflection position of the millimeter wave transmitted from the reflection object observation unit and fluctuations in reflection intensity, and detects an abnormality in the obstacle detection device And a self-diagnosis unit.

  Here, the self-diagnosis unit inputs the distance from the determination processing unit to the reflection position of the millimeter wave and the reflection intensity, the reflection intensity deviates from a predetermined intensity range according to natural fluctuation for a certain time, and the reflection When the distance to the position deviates from the level crossing, it is determined that an abnormality has occurred in the obstacle detection device.

JP 2000-103283 A JP 2005-23615 A

  When the above-described corner reflector of Patent Document 1 is used, millimeter waves are less susceptible to rain and snow than lasers and ultrasonic sensors, but millimeter waves are not easily affected by rain or snow attached to the reflector. There is a problem that the reflectivity fluctuates. In the obstacle detection device of Patent Document 2, although a technique for preventing undetected or erroneous detection of an obstacle using a reference signal by a reflector is shown, the reference signal deteriorates due to disturbance such as rain or snow. When the performance monitoring of the device itself is uncertain, it is further necessary to determine abnormality of the reference signal by the self-diagnosis unit.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a radar transceiver that can compensate for reflectance fluctuations of a reflector due to snow, rain, or the like.

To achieve the above object, a radar transceiver according to the present invention, a radar transmission antenna that sends millimeter waves, in a radar transceiver comprising: a radar receiving antenna for receiving the millimeter wave, the radar A virtual reflector that receives a millimeter wave transmitted from the transmitting antenna and transmits the received millimeter wave to the radar receiving antenna, and a millimeter wave that is transmitted from the radar transmitting antenna, reflected by the target, and received by the radar receiving antenna. And means for observing the target based on the millimeter wave received and transmitted by the virtual reflector and received by the radar receiving antenna. The virtual reflector is provided between the radar transmitting antenna and the radar receiving antenna. A transmission / reception antenna, a delay line for delaying a millimeter wave received and transmitted by the transmission / reception antenna, and a transmission / reception antenna And a substrate on which a delay line is disposed, the substrate is disposed so as to block between the radar transmission antenna and the radar reception antenna, and a part of the transmission / reception antenna is disposed on one surface of the substrate, The other part of the transmission / reception antenna is disposed on the other surface of the substrate, and one surface of the substrate is directed toward the radar transmission antenna, and the other surface of the substrate is directed toward the radar reception antenna. And

  In the radar transceiver according to the present invention, the radar transmitting antenna, the radar receiving antenna, and the virtual reflector are arranged inside a radome that prevents adhesion of rain and snow.

The radar transceiver according to the present invention preferably includes monitoring means for adjusting characteristics of the virtual reflector, the virtual reflector includes an attenuator for adjusting transmission / reception characteristics of the transmission / reception antenna, and the delay line includes the transmission / reception antenna and the transmission / reception antenna. The monitoring means provided between the attenuator and the attenuator adjusts the attenuator based on the millimeter wave received by the radar receiving antenna .

  Furthermore, in the radar transceiver according to the present invention, the delay line of the virtual reflector is a delay circuit using a microstrip line.

  Like the radar transceiver according to the present invention, the radar transmitting antenna and the radar receiving antenna are arranged in the radome, and a virtual reflector is installed in the vicinity of these to compensate for the signal so that rain, snow, etc. It is possible to make it less susceptible to disturbances. In addition, the use of the virtual reflector has an effect that the performance of the radar itself can be monitored.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 shows a configuration of a radar transceiver 10 that detects whether an obstacle such as a vehicle 9 has entered a detection area. A radar transceiver 10 includes a radar transmission antenna 1 that radiates a signal of an FMCW transmitter 11 that modulates and transmits a millimeter wave band with a triangular wave to a detection region, a reflector 5 that reflects a transmitted signal, and a virtual reflector 20; While receiving the signal from the reflector 5 as a reference signal, for example, the radar receiving antenna 2 that receives the reflected signal from the vehicle 9 entering the area, the mixer 15, the beat frequency processor 12, the display 13, And a monitoring circuit 14. The virtual reflector 20 includes a transmission / reception antenna 3, a delay line 21, and an attenuator 22.

  The radar transceiver 10 obtains a beat signal including a signal component of a distance to the target or the like by mixing the received wave fRn reflected from the target or the like with a part fM of the transmission wave by the mixer 15. . The beat frequency processor 12 obtains the distance to the obstacle from the beat signal by the reception wave (fR2) of the reflector 5, the reception wave (fR0) of the virtual reflector 20, and the reception wave (fR1) of the obstacle. Next, the display 13 obtains and displays the relative velocity of the obstacle based on the distance information obtained by the beat frequency processor 12 and displays the radio wave intensity and distance between the reflector 5 and the virtual reflector 20 on the monitoring circuit 14. Is output. The monitoring circuit 14 adjusts the attenuator 22 of the virtual reflector 20 based on the radio wave intensity output from the FMCW transmitter 11 and the radio wave intensity and distance obtained from the display 13, thereby monitoring the performance of the radar transceiver 10. I do.

  FIG. 2 shows an outline of an antenna unit 31 in which the radar transmitting antenna 1 and the radar receiving antenna 2 are individually arranged. The antenna unit 31 includes a radome 27, a radar transmission antenna 1, a radar reception antenna 2, and a virtual reflector 20 disposed on the stay 26.

  One characteristic of the present embodiment is that, as shown in FIG. 2, the transmission / reception antenna 3 of the virtual reflector is arranged between the radar transmission antenna 1 and the radar reception antenna 2 arranged side by side. The spiral delay line and the attenuator 22 are mounted as a printed circuit board.

  By adopting such a configuration, a virtual reflector equivalent to a reflector that is separated by 20-30 cm inside the device without being disturbed by rain, snow, or the like is constituted by a transmission / reception antenna and a delay line. Specifically, a printed circuit board having a high dielectric constant was used, a time delay corresponding to the spatial delay time of a conventional reflector was realized on the printed circuit board, and an attenuator was mounted to vary the radio field intensity.

  FIG. 3 shows an outline of an antenna unit 32 having a radar transmission / reception antenna 4 sharing a radar transmission antenna and a radar reception antenna. In the embodiment of FIG. 3, the antenna is shared in order to reduce the size and cost of the device. In FIG. 3, the virtual reflector 20 arranges the transmission / reception antenna 3 so as to partially protrude from the outer peripheral portion of the radar transmission / reception antenna 4, but is not limited to the embodiment of FIG. 3, any of the four sides of the radar transmission / reception antenna 4. It may be arranged on either side.

  FIG. 4 shows the characteristics of the received intensity distribution with respect to the distance in the radar transceiver. The vertical axis represents the received intensity and the horizontal axis represents the distance according to the delay time. In the drawing, R0 is a virtual reflector 20 arranged at a virtual distance (20-30 cm) away from the main body of the resonator, R1 is a vehicle 9 that is an obstacle, and R2 is due to a reflected signal of the reflector 5.

  Normally, the reflector 5 in FIG. 1 provides a reference signal for a target and monitors the performance of the radar itself. However, when the reflector 5 is attached with rain, snow, etc., the performance monitoring of the reception intensity modulator itself is performed. May be indeterminate. Therefore, in this embodiment, a virtual reflector 20 is provided. In addition, in order to secure the obstacle detection distance range, the monitoring circuit 14 reduces the reception intensity of the attenuator 22 so that the virtual reflector 20 is not affected by normal measurement.

  FIG. 5 shows the configuration of the virtual reflector 20. The virtual reflector 20 has a part of a transmitting / receiving antenna and a spiral delay line 21 arranged on the front and back sides of a high dielectric constant printed circuit board, and an end of the delay line is opened or short-circuited by an attenuator 22. The signal is totally reflected. Further, the reception intensity of the virtual reflector 20 is varied by controlling the attenuator 22 by the monitoring circuit 14.

  Note that one of the characteristic matters in the present embodiment is that the limit position on the near side of the detection distance range is set without matching the delay time of the normal reflector in order to shorten the delay line length of the virtual reflector 20. It is that. By adopting such a configuration, the virtual reflector 20 can be reduced in size, and can be displayed as a reference signal in front of the detection distance range of the display 13.

  As described above, by using this embodiment, the radar transmission antenna and the radar reception antenna are arranged in the radome, and a virtual reflector is installed in the vicinity of these to compensate for the signal. It becomes possible to make it less susceptible to disturbances such as rain and snow. Further, by using a virtual reflector, it is possible to monitor the performance of the radar itself.

  In the present embodiment, the virtual reflector is disposed in the radome. However, it is needless to say that the radome is not necessary when there is a cover or a roof for preventing adhesion of rain or snow.

It is a block diagram which shows the structure of the radar transmitter / receiver which concerns on embodiment of this invention. It is a perspective view which shows the outline | summary of the antenna part of this embodiment. It is a perspective view which shows the outline | summary of the antenna part which has the radar transmission / reception antenna which shared the radar transmitting antenna and radar receiving antenna of this embodiment. It is explanatory drawing explaining the characteristic of the received intensity distribution with respect to the distance in the radar transmitter-receiver of this embodiment. It is explanatory drawing explaining the structure of the virtual reflector of this embodiment.

Explanation of symbols

  1 radar transmitting antenna, 2 radar receiving antenna, 3 transmitting / receiving antenna, 4 radar transmitting / receiving antenna, 5 reflector, 9 vehicle, 10 radar transceiver, 11 transmitter, 12 beat frequency processor, 13 display, 14 monitoring circuit, 15 mixer , 20 Virtual reflector, 21 Delay line, 22 Attenuator, 26 Stay, 27 Radome, 31, 32 Antenna part.

Claims (4)

A radar transmitting antenna that sends millimeter waves, in a radar transceiver comprising: a radar receiving antenna for receiving millimeter waves, a,
A virtual reflector that receives the millimeter wave transmitted from the radar transmission antenna and transmits the received millimeter wave to the radar reception antenna;
In addition to the millimeter wave transmitted from the radar transmitting antenna, reflected by the target, and received by the radar receiving antenna, received and transmitted by the virtual reflector and received by the radar receiving antenna, Means for observation,
With
Virtual reflector is
A transmission / reception antenna disposed between the radar transmission antenna and the radar reception antenna;
A delay line that delays the millimeter wave received and transmitted by the transmitting and receiving antenna;
A substrate on which a transmission / reception antenna and a delay line are arranged;
With
The substrate is arranged to block between the radar transmitting antenna and the radar receiving antenna,
A part of the transmission / reception antenna is arranged on one surface of the substrate,
The other part of the transmission / reception antenna is arranged on the other surface of the substrate,
A radar transceiver characterized in that one surface of the substrate is directed toward the radar transmitting antenna and the other surface of the substrate is directed toward the radar receiving antenna. The radar transceiver according to claim 1,
Radar transmitting antenna and the radar receiving antenna and virtual reflector, radar transceiver, characterized in that disposed inside the radome to prevent adhesion of rain or snow. The radar transceiver according to claim 1 or 2,
A monitoring means for adjusting the characteristics of the virtual reflector,
The virtual reflector includes an attenuator that adjusts the transmission / reception characteristics of the transmission / reception antenna,
The delay line is provided between the transmission / reception antenna and the attenuator,
The radar transmitter / receiver characterized in that the monitoring means adjusts the attenuator based on the millimeter wave received by the radar receiving antenna. The radar transceiver according to any one of claims 1 to 3 ,
De Ireirain is a radar transceiver which is a delay circuit according to the microstrip line.

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