JP2008209225A - Radar apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a FW-CW system radar apparatus for removing a noise generated within the apparatus, and FM-CW system radar apparatus for reducing a cost, without complicating processes. <P>SOLUTION: The FM-CM system radar apparatus for transmitting a transmission wave from an antenna and receiving a reflection wave as the transmission wave reflected from a target through the antenna includes: a transmission/reception signal generating section for generating a transmission signal for transmitting the transmission wave to the antenna, and generating a reception signal as a reception wave received by the antenna; a noise generating section having the same constitution as the transmission/reception signal generating section; and a noise canceling section for generating a noise signal with a phase reversed to the reception signal generated by the transmission/reception signal generating section, adding the phase-reversed noise signal to the reception signal from the transmission/reception signal generating section, and generating the reception signal in which the noise signal generated in the transmission/reception signal generating section is removed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an FM-CW radar device that removes noise.

  It is known that FM-CW (Frequency Modulated-Amplitude Modulated) conversion noise and near-field noise are generally generated in a radar apparatus based on FM-CW (Frequency Modulated-Continuous Wave).

  In order to remove such noise, conventionally, the frequency of any one of a local signal, a transmission wave, and a received reflected wave is slightly shifted, so that FM-AM noise in a low frequency region is increased to a high frequency. An FM-CW radar apparatus that is shifted to a region and easily separates noise by a filter is disclosed (for example, Patent Document 1 below).

  Further, the apparatus includes a balanced mixer that mixes a part of the transmission wave and the reception wave and outputs a 0-phase signal and a π-phase signal, and a means for adding the 0-phase signal and the π-phase signal, An FM-CW radar device that removes noise by adding AM conversion noise to a beat signal is also disclosed (for example, Patent Document 2 below).

  Furthermore, a bandpass filter and a frequency analyzer are provided for the received signal, and compensation according to the frequency characteristics of the bandpass filter is performed according to the analysis result analyzed by the frequency analyzer, and then the obstacle is also detected. Also disclosed is an FM-CW radar that calculates the distance and the like (for example, Patent Document 3 below).

  Further, a communication processing device is disclosed in which the noise component is removed by performing inverse Fourier transform on the signal of the noise component and storing it in the memory, and then subtracting the signal obtained by the Fourier transform (for example, The following patent document 4).

In addition, two parts up to parts that may generate random noise, and an averaging unit that averages these outputs are provided, and even if noise occurs, it is averaged to reduce the effect A navigation receiver is also disclosed (for example, Patent Document 5 below).
Japanese Patent Laid-Open No. 4-178589 JP-A-4-184184 JP-A-8-166442 JP 2003-139847 A Japanese Patent Laid-Open No. 9-178834

  However, the FM-CW radar apparatus according to Patent Document 1 must be provided with a PLO (Phase Locked Oscillator) for shifting the frequency, which increases the cost of the entire apparatus.

  In Patent Documents 2 and 3, the local signal (0 phase) and the received signal (π phase) are weighted and in-phase added to remove the noise of the local signal and the received signal. Can not be removed. For example, a switch for switching between transmission and reception is provided in the circuit of the radar apparatus, but noise associated with turning on and off of the switch is not considered and cannot be removed.

  Furthermore, the communication processing device according to Patent Document 4 requires an operation time for storing in a memory, and a circuit for removing a delayed wave due to Fourier transform processing is necessary, so that the processing of the entire device is complicated and expensive. . In addition, it is impossible to remove noise associated with turning on / off the switch.

  Furthermore, although the receiving device according to Patent Document 5 averages noise by the averaging unit, it cannot remove all noise.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a FW-CW radar device that removes noise generated inside the device.

  Another object of the present invention is to provide an FM-CW radar device which is low in cost without complicated processing.

  In order to achieve the above object, according to an embodiment of the present invention, an FM-CM radar that transmits a transmission wave from an antenna and receives a reflection wave of the transmission wave reflected by a target by the antenna. In the apparatus, a transmission / reception signal generation unit that generates a transmission signal for transmitting a transmission wave to the antenna and generates a reception signal for the reception wave received by the antenna, and the transmission / reception signal generation unit A noise generation unit having the same configuration as the above, and generating a noise signal having a phase opposite to that of the reception signal generated by the transmission / reception signal generation unit. And a noise cancellation unit that generates a reception signal from which the noise signal generated by the transmission / reception signal generation unit is removed.

  According to another embodiment of the present invention, further comprising a voltage controlled oscillator, the transmission / reception signal generator is configured to distribute an oscillation signal from the voltage controlled oscillator, and from the distributor A first amplifying unit for amplifying a transmission signal, a second amplifying unit for amplifying a received signal received by the antenna, a received signal from the second amplifying unit, and an oscillation signal from the distributing unit are mixed. And a mixing unit configured to transmit a transmission wave based on a signal from the first amplifying unit, and an output signal from the mixing unit is output to the noise canceling unit.

  Furthermore, according to another embodiment of the present invention, the noise canceling unit is configured to adjust the attenuation amount of the noise signal output from the noise generation unit, and the noise signal whose attenuation amount is adjusted. A variable phase shifter that generates the anti-phase noise signal, and an addition unit that adds the anti-phase noise signal and the reception signal from the transmission / reception signal generation unit. The received signal from which is removed is output.

  Furthermore, according to another embodiment of the present invention, the received signal from the noise canceling unit is input, a noise component signal is extracted from the received signal, and the anti-phase noise signal is extracted at the timing of the noise signal. It is further characterized by further comprising a timing adjustment unit that controls the generation.

  According to the present invention, it is possible to provide an FM-CW radar device that removes noise generated inside the device. In addition, according to the present invention, it is possible to provide an FM-CW radar device that is not complicated and has a low cost.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a configuration example of a radar apparatus 100 based on the FM-CW method.

  The radar apparatus 100 includes an antenna 5, an RF unit 10, and an IF / BB unit 30.

  The antenna 5 is also used as a transmission / reception antenna, and transmits a triangular transmission wave and also receives a reflected wave with respect to the transmission wave reflected on the target.

  The RF unit 10 is a circuit for generating a transmission signal for the antenna 5, and is a circuit for generating a reception signal from a reception wave received by the antenna 5.

  The IF / BB unit 30 is a so-called signal processing circuit, which generates a triangular wave that is a transmission wave or extracts a beat signal that is a feature of the present system from an IF signal with respect to a reception signal, and calculates the distance and relative distance of a target object. It is a circuit for calculating the speed.

  As shown in FIG. 1, the RF unit 10 includes a VCO 11 (Voltage Controlled Oscillator), an MMIC unit 12, a noise generation unit 13, a first variable attenuator 14, and a first variable phase shifter 15. And a second variable attenuator 16, a second variable phase shifter 17, a first distributor 18, an amplifier 19, a BPF (Band Pass Filter) 20, and a comparator 21.

  The VCO 11 outputs an oscillation signal having a predetermined frequency. However, the VCO 11 is controlled by a triangular wave generation circuit 31 described later and outputs an oscillation signal.

  The MMIC unit 12 creates a transmission signal based on the oscillation signal from the VCO 11 and outputs a beat signal from the reception signal received by the antenna 5. The MMIC unit 12 has a function as a transmission / reception signal generation circuit.

  As shown in FIG. 1, the MMIC unit 12 includes a second distributor 121 and an amplifier (Amp) 122 in the transmission system, and an amplifier (Amp) 123 and a mixer 124 in the reception system. Consists of In the transmission system, a transmission signal is generated by the second switching unit 121 and the amplifier 122. In the receiving system, the received signal received from the antenna 5 is amplified by the amplifier 123 and mixed with the oscillation signal by the mixer 124 to generate a beat signal.

  The noise generation unit 13 has the same configuration as the MMIC unit 12 and reproduces a noise signal generated in the MMIC unit 12. As shown in FIG. 1, the noise generating unit 13 includes a third distributor 131, amplifiers (Amp) 132 and 133, and a mixer 134. The third switching unit 131 of the noise generation unit 13 and the second distributor 121 of the MMIC unit 12 have the same configuration, and the two amplifiers 132 and 133 of the noise generation unit 13 and the two amplifiers of the MMIC unit 12 122 and 123 have the same configuration, and the mixer 134 of the noise generation unit 13 and the mixer 124 of the MMIC unit 12 have the same configuration.

  The first variable attenuator 14 and the first variable phase shifter 15 are connected to the input stage of the amplifier 133 of the noise generator 13, and the second variable attenuator 16 and the first variable attenuator 16 are connected to the output stage of the mixer 134. Two variable phase shifters 17 are connected.

  The first variable attenuator 14 and the second variable phase shifter 15 generate a signal having a component that is the same as or close to the received signal received by the antenna 5. That is, the signal output from the amplifier 132 of the noise generator 13 is attenuated to a predetermined level by the first variable attenuator 14 and becomes a signal having a predetermined phase amount by the first variable phase shifter 15. The attenuation amount and the phase amount are controlled based on a control signal from the comparator 21.

  This signal is amplified by the amplifier 133 and mixed with the oscillation signal from the third distributor 131 by the mixer 134. In the mixer 134, the amplified signal and the oscillation signal are mixed, so that the component of the oscillation signal in the amplified signal and the oscillation signal from the third distributor 131 cancel each other, and the noise generator 13 Only the noise component is generated. That is, since the noise generation unit 13 has the same configuration as the MMIC unit 12, all of the FM-AM conversion noise generated in the MMIC unit 12, the neighborhood noise, and the noise accompanying the on / off of the amplifiers 122 and 123 are all included. A signal having the same component as the noise component is output.

  The noise signal output from the noise generator 13 is input to the second variable attenuator 16 and attenuated by a predetermined amount. The second variable phase shifter 17 generates a signal whose phase is shifted by a predetermined amount. The attenuation amount and the phase amount are controlled so as to be the same attenuation amount as the noise component of the reception signal output from the MMIC unit 12 and an antiphase phase amount (for example, 180 °). The attenuation amount and the phase amount are controlled by the control signal from the comparator 21.

The first distributor 18 receives the signal from the mixer 124 of the MMIC unit 12 and the signal from the second variable phase shifter 17, adds these two signals, and outputs the result. The first distributor 18 receives the beat signal from the MMIC unit 12 and the noise signal from the second variable phase shifter 17. Then, by adding these two signals, the noise component signal of the beat signal and the noise signal whose phase is reversed cancel each other, and a beat signal (reception signal) having no noise component is output. That means
{(Received signal from antenna 5) + (noise signal of MMIC unit 12)} + (noise signal of opposite phase of noise generating unit 13) = (received signal without noise signal)
It becomes the relationship. Noise components cancel each other out by the first distributor 18, and FM-AM conversion noise and nearby noise generated in the MMIC unit 12, and noise signals such as noise caused by turning on and off the amplifiers 122 and 123 are surely received. Can be removed.

  The second variable attenuator 16, the second variable phase shifter 17, and the first distributor 18 constitute a noise cancellation circuit.

  The RF unit 10 further includes an amplifier 19, a BPF 20, and a comparator 21, and the received signal output from the first distributor 18 is amplified by the amplifier 19, and a noise component is extracted by the BPF 20. The comparator 21 adjusts the attenuation timing of the noise signal generated by the noise generation unit 13 and the timing for making the phase opposite to each other from the noise component. A control signal based on the adjusted amount is output from the comparator 21, and a noise signal is output from the noise generation unit 13 at the same timing as the noise component of the reception signal output from the MMIC unit 12.

  The reception signal output from the first distributor 18 is output to the IF unit 35 of the IF / BB unit 30. The IF unit 35 includes a BPF 351, a mixer 352, an amplifier 353, and an LPF (Low Pass Filter) 354. The IF unit 35 obtains a reception signal having a predetermined component. This received signal is output to the BB unit 34 and subjected to predetermined signal processing.

  The BB unit 34 includes an A / D conversion circuit 354, a CAN (Control Area Network) 344, a CPU 343, a SW Control 342, and a D / A conversion circuit 341.

  The A / D conversion circuit 354 converts the reception signal output from the IF unit 35 into a digital signal. Conversely, the D / A conversion circuit 341 converts the received signal into an analog signal. The CAN 344 is a circuit that controls each ECU (Electric Control Unit) connected by, for example, an in-vehicle LAN (Local Area Network). The SW Control 342 is a circuit that controls various switches.

  The IF / BB unit 30 further includes a triangular wave generation circuit 31, a driver circuit 32, and a power supply circuit 33.

  The triangular wave generation circuit 31 is a circuit that generates a signal for transmitting a triangular wave from the antenna 5, and a signal having a predetermined frequency is output from the VCO 11 based on this signal. The driver circuit 32 is a circuit for controlling other parts (not shown) of the RF unit 10. The power supply circuit 33 is a circuit for supplying power to the RF unit 10.

  FIG. 2 is a diagram illustrating an example of a noise signal (noise data). As shown in the figure, in the radar apparatus 100 based on the FM-CW method, second, third,... Noise signals are generated at predetermined frequencies centering around the SW frequency that is a transmission / reception switching frequency. In this embodiment, since the noise component generated in the MMIC unit 12 can be surely removed from the noise signal, the noise signal is completely removed or the noise component lower than the level shown in FIG. A spectrum can be obtained.

  As described above, in this embodiment, the noise generation unit 13 having the same configuration as that of the MMIC unit 12 is provided to generate the same noise signal as that of the MMIC unit 12, and the second variable phase shifter 17, the first distributor 18 and the like. By canceling out the noise component signal of the received signal, the FM-AM conversion noise generated in the MMIC unit 12 and the nearby noise, and the reception by removing the noise caused by switching between transmission and reception (by turning on and off the amplifiers 122 and 123) are removed. A signal can be obtained.

  In addition, since the noise component is removed by the noise generating unit 13, the second variable attenuator 16, the second variable phase shifter 17, and the first distributor 18, the processing becomes complicated with a simple configuration. In addition, the radar apparatus 100 with further reduced costs is obtained.

  In the above-described example, the antenna 5 has been described as one transmitting / receiving antenna. Of course, the present embodiment is not limited to this, and a plurality of transmission / reception antennas may be used, a plurality of transmission antennas and a plurality of reception antennas may be used, or a combination thereof. In either case, the present invention can be implemented in exactly the same manner as the above-described example, and has the same effect.

  The radar apparatus 100 according to the present embodiment is preferably mounted on a vehicle and used for inter-vehicle distance control and rear-end collision prevention.

FIG. 1 is a diagram illustrating a configuration example of a radar apparatus. FIG. 2 is a diagram illustrating an example of noise data.

Explanation of symbols

10 RF unit, 11 VCO (voltage controlled oscillator), 12 MMIC unit, 13 noise generation unit, 14 first variable attenuator, 15 first variable phase shifter, 16 second variable attenuator, 17 second variable phase shifter , 18 First distributor, 19 Amplifier, 20 BPF, 21 Comparator, 30 IF / BB section, 31 Triangular wave generation circuit, 32 Driver circuit, 33 Power supply circuit, 34 BB section, 35 IF section, 100 Radar apparatus

Claims (4)

In an FM-CM radar device that transmits a transmission wave from an antenna and receives a reflection wave of the transmission wave reflected by a target using the antenna.
A transmission / reception signal generator for generating a transmission signal for transmitting a transmission wave to the antenna, and generating a reception signal for the reception wave received by the antenna;
A noise generation unit having the same configuration as the transmission / reception signal generation unit;
The transmission / reception signal generation unit generates a noise signal having a phase opposite to that of the reception signal generated by adding the reception signal from the transmission / reception signal generation unit, and the transmission / reception signal generation unit. And a noise cancellation unit that generates a reception signal from which the noise signal generated in step (2) is removed. Furthermore, a voltage controlled oscillation unit is provided,
The transmission / reception signal generation unit amplifies a reception signal received by the antenna, a distribution unit that distributes an oscillation signal from the voltage controlled oscillation unit, a first amplification unit that amplifies a transmission signal from the distribution unit, and A second amplifying unit; and a mixing unit that mixes the received signal from the second amplifying unit and the oscillation signal from the distributing unit,
The radar apparatus according to claim 1, wherein a transmission wave is transmitted to the antenna based on a signal from the first amplification unit, and an output signal from the mixing unit is output to the noise cancellation unit.   The noise cancellation unit includes: a variable attenuator that adjusts the attenuation amount of the noise signal output from the noise generation unit; and a variable phase shifter that generates the noise signal having the opposite phase with respect to the noise signal in which the attenuation amount is adjusted. And an adder that adds the negative-phase noise signal and the received signal from the transmission / reception signal generator, and the adder outputs the received signal from which the noise signal has been removed. The radar apparatus according to claim 1, wherein: And a timing adjusting unit that receives the received signal from the noise canceling unit, extracts a noise component signal from the received signal, and controls the noise signal to be generated at the timing of the noise signal. The radar apparatus according to claim 1.

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