JP2007003291A - Chirp radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chirp radar system which can prevent the false detection of a target under the condition that radar radio waves with a chirp waveform are emitted simultaneously from a large number of vehicles. <P>SOLUTION: The chirp radar system emits radar radio waves with a chirp waveform, receives radio waves reflected off the target, and detects the target. The system comprises a waveform shaping means 10 for outputting the chirp waveform, digital waveform shaping means 20, 80 for outputting a digital waveform of code data unique to the system, and a composite waveform shaping means 30 for outputting a composite wave obtained by modulating the chirp waveform with the digital waveform. The system emits the radio waves of the composite wave output from the composite waveform shaping means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a chirp radar device, and more particularly, to a chirp radar device that detects a target by emitting a radar radio wave having a chirp waveform.

  In order to monitor the surroundings of a vehicle mounted on a vehicle, a chirp radar device that detects a target by emitting a radar radio wave having a chirp waveform is used. Since the chirp waveform has a wide bandwidth and can reduce the signal strength, the power consumption of the radar apparatus can be kept low.

For example, Patent Document 1 includes a first mixer, a second mixer, and an intermediate frequency synthesizer that adds the outputs of the first and second mixers, and outputs the intermediate frequency synthesizer. Describes a digital chirp signal generation circuit that obtains a chirp signal in the intermediate frequency band to reduce power consumption and circuit size.
Japanese Patent No. 2594543

  When a chirp radar device is mounted on a vehicle and the surroundings of the vehicle are monitored, in a situation where a radar wave with a chirp waveform is simultaneously emitted from many vehicles, the radar waves with a chirp waveform emitted from each vehicle are mixed. In addition, there is a problem that a target may be erroneously detected.

  The present invention has been made in view of the above points, and provides a chirp radar device capable of preventing erroneous detection of a target in a situation where a radar wave having a chirp waveform is simultaneously emitted from many vehicles. Objective.

The chirp radar device of the present invention is a chirp radar device that detects a target by emitting a radio wave of a chirp waveform and receiving a radio wave reflected by the target.
Chirp waveform shaping means for outputting a chirp waveform;
Digital waveform shaping means for outputting a digital waveform of device-specific code data;
A synthetic wave shaping means for outputting a synthetic wave obtained by modulating the chirp waveform with the digital waveform;
By emitting radio waves of the synthetic wave output from the synthetic wave shaping means,
It is possible to prevent erroneous detection of a target in a situation where a radar wave having a chirp waveform is simultaneously emitted from many vehicles.

In the chirp radar device,
The digital waveform shaping means outputs a digital waveform including the code data and vehicle information,
By having a signal processing means for demodulating a digital waveform including the code data and vehicle information from a received signal to obtain the vehicle information,
It is possible to know vehicle information of vehicles in the vicinity.

In the chirp radar device,
The vehicle information is a vehicle type,
It is possible to know the vehicle type of vehicles existing in the vicinity.

  According to the present invention, erroneous detection of a target can be prevented in a situation where a radar wave having a chirp waveform is simultaneously emitted from many vehicles.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a configuration diagram of a first embodiment of a chirp radar apparatus according to the present invention. In the figure, a chirp waveform shaper 10 shapes a chirp waveform as shown in FIG. 2A, which has a wide bandwidth by frequency sweeping of a sine wave, and supplies it as a carrier wave signal to the combined waveform shaper 30.

  The digital waveform shaper 20 forms a digital waveform of code data unique to the apparatus as shown in FIG. The digital waveform of the code data is generated in synchronization with the frequency sweep waveform of the chirp waveform shaper 10.

  The composite waveform shaper 30 multiplies the carrier wave signal from the chirp waveform shaper 10 and the digital waveform of the code data from the digital waveform shaper 20 to perform PSK modulation, and inverts the carrier wave signal at the value 1 portion of the code data. Instead, a composite wave as shown in FIG. 2C is generated by inverting the carrier signal at the value 0 portion of the code data. The synthesized wave of the PSK modulated wave output from the synthesized waveform shaper 30 is supplied to the switching unit 40.

  The switching unit 40 switches between reception and transmission of the antenna 50. At the time of transmission, the switching unit 40 supplies the combined wave output from the combined waveform shaper 30 to the antenna 50 and emits it from the antenna 50, and the combined wave is transmitted to the signal processing unit 60. To supply. At the time of reception, the signal received by the antenna 50 is supplied to the signal processing unit 60.

  In addition, without providing the switching unit 40, the combined wave output from the combined waveform shaper 30 is supplied to the antenna 50 and the signal processing unit 60 as the transmitting antenna, and the received signal received by the separate receiving antenna is subjected to signal processing. It is good also as a structure supplied to the part 60. FIG.

  The signal processing unit 60 correlates the waveform of the received signal of the antenna 50 and the synthesized wave from the synthesized waveform shaper 30, and obtains the time difference until the emitted synthesized wave is reflected and received by the target, This is supplied to the distance measuring unit 70. The distance measuring unit 70 obtains the distance to the object from this time difference. Further, the relative speed of the object is obtained by differentiating the distance with respect to time.

  In this way, the synthesized wave PSK-modulates the chirp waveform with the device-specific code data, and the code data is different for each radar device. Therefore, in a situation where radar waves with a chirp waveform are simultaneously emitted from many vehicles. Even if it exists, the reflected wave of the synthetic wave emitted from the own apparatus can be identified, and the erroneous detection of the target can be prevented.

  The chirp waveform is a spread waveform whose bandwidth is widened by a frequency sweep of a sine wave, but is further spread by PSK modulation using code data to widen the bandwidth, thereby further reducing the signal strength, The power consumption of the radar apparatus can be further reduced.

Second Embodiment
FIG. 3 shows a block diagram of a second embodiment of the chirp radar device of the present invention. In the figure, the same parts as those in FIG.

  In FIG. 3, a chirp waveform shaper 10 shapes a chirp waveform as shown in FIG. 2A, in which the bandwidth is widened by a frequency sweep of a sine wave, and supplies it as a carrier wave signal to the combined waveform shaper 30.

  As shown in FIG. 4, the digital waveform shaper 80 forms a fixed-length digital waveform made up of a head code, an information code, and code data, and supplies it to the combined waveform shaper 30. The head code is a predetermined bit pattern such as “0101”, for example. The information code as the vehicle information is a code for identifying a vehicle type such as a general vehicle, a fire engine, a police car. The code data is a code unique to the apparatus as shown in FIG.

  A digital waveform composed of the head code, information code, and code data is generated in synchronization with the frequency sweep waveform of the chirp waveform shaper 10.

  The composite waveform shaper 30 multiplies the carrier wave signal from the chirp waveform shaper 10 and the digital waveform from the digital waveform shaper 20 to perform PSK modulation, and the carrier wave at the first code, information code, and code data value 1 portion. A synthesized wave as shown in FIG. 2C is generated without inverting the signal and inverting the carrier signal at the value 0. The combined wave of the PSK modulated wave output from the combined waveform shaper 30 is supplied to the switching unit 40.

  The switching unit 40 switches between reception and transmission of the antenna 50. At the time of transmission, the switching unit 40 supplies the combined wave output from the combined waveform shaper 30 to the antenna 50 and emits it from the antenna 50, and the combined wave is transmitted to the signal processing unit 60. To supply. At the time of reception, the signal received by the antenna 50 is supplied to the signal processing units 60 and 90.

  In addition, without providing the switching unit 40, the combined wave output from the combined waveform shaper 30 is supplied to the antenna 50 and the signal processing unit 60 as the transmitting antenna, and the received signal received by the separate receiving antenna is subjected to signal processing. It is good also as a structure supplied to the parts 60 and 90. FIG.

  The signal processing unit 60 correlates the waveform of the received signal of the antenna 50 and the synthesized wave from the synthesized waveform shaper 30, and obtains the time difference until the emitted synthesized wave is reflected and received by the target, This is supplied to the distance measuring unit 70. The distance measuring unit 70 obtains the distance to the object from this time difference. Further, the relative speed of the object is obtained by differentiating the distance with respect to time.

  The signal processing unit 90 performs PSK demodulation on the reception signal of the antenna 50. Thereafter, the head code of the demodulated signal is identified to obtain an information code. Then, this information code is supplied to the display unit 100. The display unit 100 converts the information code into a vehicle type such as a general vehicle, a fire truck or a police car and displays the information code. When an emergency vehicle such as a fire truck or a police car is detected, a warning is generated by a flashing display or an alarm sound. .

  For this reason, it is possible to know the vehicle type of the vehicle existing around the host vehicle from the received signal of the synthesized wave emitted by the vehicle existing around the host vehicle.

  Note that the synthesized wave is PSK modulated with chirp waveform using device-specific code data, and the code data is different for each radar device. Can identify the reflected wave of the synthesized wave emitted from its own device, prevent false detection of the target, and the chirp waveform is a spread waveform whose bandwidth is widened by frequency sweep of the sine wave. As in the first embodiment, the signal is further spread by the PSK modulation according to the above and the bandwidth is widened, whereby the signal strength can be further reduced and the power consumption of the radar apparatus can be further reduced.

  The chirp waveform shaper 10 corresponds to the chirp waveform shaping means described in the claims, the digital waveform shapers 20 and 80 correspond to the digital waveform shaping means, the synthetic waveform shaper 30 corresponds to the synthetic wave shaping means, The signal processing unit 90 corresponds to signal processing means.

It is a block diagram of 1st Embodiment of the chirp radar apparatus of this invention. It is a signal waveform diagram of each part of the chirp radar device of the present invention. It is a block diagram of 2nd Embodiment of the chirp radar apparatus of this invention. It is a figure which shows the head code, information code, and code data which the digital waveform shaper 80 outputs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Chirp waveform shaper 20,80 Digital waveform shaper 30 Composite waveform shaper 40 Switching part 50 Antenna 60,90 Signal processing part 70 Distance measuring part 100 Display part

Claims (3)

In a chirp radar device that detects a target by emitting a radio wave of a chirp waveform and receiving a radio wave reflected by the target,
Chirp waveform shaping means for outputting a chirp waveform;
Digital waveform shaping means for outputting a digital waveform of device-specific code data;
A synthetic wave shaping means for outputting a synthetic wave obtained by modulating the chirp waveform with the digital waveform;
A chirp radar device that emits a radio wave of a synthetic wave output from the synthetic wave shaping means. The chirp radar device according to claim 1, wherein
The digital waveform shaping means outputs a digital waveform including the code data and vehicle information,
A chirp radar device comprising signal processing means for obtaining the vehicle information by demodulating a digital waveform including the code data and vehicle information from a received signal. The chirp radar device according to claim 2,
The chirp radar device, wherein the vehicle information is a vehicle type.

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