JP2006267016A - Radar equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radar apparatus which can be realized at a lower apparatus cost and can perform a precise digital beam forming process with a reduced time error.
A transmission system Tx for transmitting a transmission wave, five reception systems Rx1 to Rx5 for receiving a reflected wave of the transmission wave, and a signal obtained by mixing the transmission signal of the transmission wave and the reception signal of the reception wave , Sample hold circuits 109-1 to 109-5 that sample at a predetermined timing and fix to the sampled level for a predetermined period, and a switch that sequentially converts the outputs of the sample hold circuits 109-1 to 109-5 into digital signals 110 and an A / D converter 111, and a signal processing device 112 that determines sampling timing and performs digital beam forming processing based on the output of the A / D converter 111.
[Selection] Figure 1

Description

      The present invention relates to a radar apparatus that detects a target object by obtaining a frequency analysis result for each beam using digital beam forming.

  2. Description of the Related Art Conventionally, an in-vehicle radar device for detecting a distance, an azimuth, a relative speed, and the like with an object located in front of a vehicle to realize collision prevention and follow-up traveling is known. In this type of radar device, the detection range is determined by the antenna beam, so that the detectable angle range can be expanded without reducing the detection distance, and the orientation of the target object can be specified within the determined detection range. In this case, a technique of making the antenna beam into a multi-beam is useful.

  On the other hand, with the progress of circuit technology, high-speed digital signal processing has become possible, and digital beam forming that realizes beam formation by digital signal processing has attracted attention as a multi-beam technique (for example, patents) Reference 1).

      A configuration diagram of a radar apparatus (conventional example 1) using conventional digital beam forming is shown in FIG. The radar apparatus according to the conventional example 1 includes a transmission system Tx including a VCO (voltage controlled oscillator) 201, an amplifier 202, and a transmission antenna 203. The five reception systems Rx1 to Rx5 have reception antennas 204-1 to 204-5, respectively. RF amplifiers 205-1 to 205-5, mixers 206-1 to 206-5, BB amplifiers 207-1 to 207-5, and bandpass filters 208-1 to 208-5 are provided, and an A / D converter 211 is provided. -1 to 211-5 and a signal processing device 212.

In the radar apparatus according to Conventional Example 1 having such a configuration, a transmission wave modulated by the VCO 201 is transmitted via the transmission antenna 203 in the transmission system Tx, and a plurality of reception antennas constituting the array antenna are received in the reception systems Rx1 to Rx5. The reflected waves of the transmission waves transmitted by 204-1 to 204-5 are received simultaneously. Beat signals B1 to B5 are generated by mixing the received signal with local signals (VCO 201 output) having the same frequency as the transmission signal, and the beat signals B1 to B5 are A / D converter 211-1 at the same timing. A signal processing device 212 that performs A / D conversion to a digital signal by ˜211-5 and takes in the digital signal, performs digital beam forming processing (including phase calculation in each beat signal B1 to B5) based on amplitude and phase information of each signal Beam forming is performed by performing digital signal processing such as weighting and adding.
JP-A-6-88869

      However, in the radar apparatus according to Conventional Example 1 described above, the same number of expensive A / D converters (211-1 to 211-5) as the number of receiving antennas (204-1 to 204-5) constituting the array antenna are used. ), And the radar device as a whole is very expensive.

  Next, FIG. 4 shows a configuration diagram of a radar apparatus (conventional example 2) in which the number of A / D converters is reduced to one to reduce the apparatus cost in response to the problem related to the conventional example 2. . The radar apparatus of Conventional Example 2 includes a VCO 301, an amplifier 302, and a transmission antenna 303 in a transmission system Tx, and reception antennas 304-1 to 304-5 and RF amplifiers 305-1 to Rx5 in five reception systems Rx1 to Rx5, respectively. 305-5, mixers 306-1 to 306-5, BB amplifiers 307-1 to 307-5, and bandpass filters 308-1 to 308-5, and further includes a switch 310, an A / D converter 311 and a signal The configuration includes a processing device 312.

      That is, a switch 310 is provided in front of the A / D converter 311, and the beat signals B 1 to B 5 are A / D converted into digital signals by the A / D converter 311 in a time division manner, and the digital signals are taken in. The processing device 312 performs digital beam forming processing based on the amplitude and phase information of each signal. However, since the radar apparatus according to Conventional Example 2 has a configuration in which the received signals received at the same timing by the plurality of receiving systems Rx1 to Rx5 cannot be processed, the amplitude of each received signal (beat signals B1 to B5) In addition, there is a problem that an error occurs in the phase information.

      The present invention has been made in view of the above-described conventional circumstances, and can be realized at a lower apparatus cost, and can reduce the time error included in the amplitude and phase information of the signal and perform an accurate digital beam forming process. An object of the present invention is to provide a radar apparatus capable of performing the above.

      In order to solve the above-described problem, a radar apparatus according to a first aspect of the present invention includes a transmission unit that transmits a transmission wave (for example, the transmission system Tx in the embodiment) and an N that receives a reflected wave of the transmission wave. A signal obtained by mixing a transmission signal of the transmission wave and a reception signal of the reception wave with a predetermined number of reception means (for example, reception systems Rx1 to Rx5 in the embodiment) (N is a positive integer of 2 or more) N sample-and-hold means (for example, sample-hold circuits 109-1 to 109-5 in the embodiment) that sample at timing and fix the sampled level for a predetermined period, and outputs of the N sample-and-hold means A / D conversion means (for example, the switching device 110 and the A / D converter 111 in the embodiment) for sequentially converting the signals into digital signals, and the sampling units in the N sample hold means Determining the timing, and having a digital beam signal processing means for performing a forming process on the basis of an output of the A / D converting means (e.g., signal processor 112 in the embodiment).

  According to a second aspect of the present invention, the radar apparatus according to the present invention includes N (N is a positive integer greater than or equal to 2) transmission / reception means for transmitting a transmission wave and receiving a reflection wave of the transmission wave; N sample-and-hold means for sampling a signal obtained by mixing the transmission signal and the received signal of the received wave at a predetermined timing and fixing the signal to the sampled level for a predetermined period; and outputs of the N sample-and-hold means A / D conversion means for sequentially converting the signal into a digital signal, and signal processing means for determining a sampling timing in the N sample and hold means and performing digital beam forming processing based on the output of the A / D conversion means, It is characterized by having.

  The radar apparatus of the present invention having the above configuration samples a signal obtained by mixing the transmission signal and the reception signal at a predetermined timing, and sequentially converts the signal fixed at the sampling level into a digital signal by the A / D conversion means. Therefore, it is possible to configure with one A / D conversion means without requiring the same number of expensive A / D converters as the number N of receiving means or transmitting / receiving means antennas, thereby reducing the cost of the radar apparatus. be able to. Further, by adjusting the sampling timing in the N sample and hold means, the signal processing means can perform the digital beam forming process based on the mixed signal at substantially the same time, so that the amplitude and phase information of the signal Therefore, accurate processing can be performed by reducing the time error included in.

  According to a third aspect of the present invention, the radar apparatus according to the first or second aspect is characterized in that the N sample and hold means sample at the same timing.

  The radar apparatus of the present invention having the above configuration performs sampling at the same timing in N sample and hold means, so that the signal processing means performs digital beam forming processing based on the mixed signal at the same time. Therefore, accurate processing can be performed without causing a time error in the amplitude and phase information of the signal.

  Furthermore, the radar device of the present invention according to claim 4 is the radar device according to any one of claims 1 to 3, wherein the transmission unit or the transmission unit of the transmission / reception unit is a transmission signal having a predetermined frequency. The transmission unit transmits the transmission wave based on the received signal, and the reception unit or the reception unit of the transmission / reception unit mixes the reception signal obtained by receiving the reflected wave with a local signal having the same frequency as the transmission signal. The N sample and hold means sample the beat signal at a predetermined timing and fix the sampled signal at the sampled level for a predetermined period.

  The radar apparatus of the present invention having the above configuration samples a beat signal obtained by mixing a transmission signal and a reception signal at a predetermined timing, and sequentially converts the signal fixed at the sampling level into a digital signal by an A / D conversion means. Therefore, the configuration of the single A / D conversion unit can reduce the cost of the radar apparatus, and the signal processing unit can perform digital beam forming processing based on the mixed beat signals at substantially the same time. Therefore, the time error included in the amplitude and phase information of the signal can be reduced and accurate processing can be performed.

      According to the radar apparatus of the present invention, a transmission unit that transmits a transmission wave, N reception units that receive a reflection wave of the transmission wave, and a signal obtained by mixing the transmission signal of the transmission wave and the reception signal of the reception wave N sampling and holding means for sampling at a predetermined timing and fixing the sampling level at a predetermined period, A / D conversion means for sequentially converting the outputs of the N sampling and holding means into digital signals, Signal processing means for determining the sampling timing in the sample hold means and performing digital beam forming processing based on the output of the A / D conversion means, so that the same number as the number N of receiving means or transmitting / receiving means antennas. It can be configured with a single A / D conversion means without requiring an expensive A / D converter, and the cost of the radar apparatus can be reduced. It can be.

  Further, by adjusting the sampling timing in the N sample and hold means, the signal processing means can perform the digital beam forming process based on the mixed signal at substantially the same time, so that the amplitude and phase information of the signal Therefore, accurate processing can be performed by reducing the time error included in.

Hereinafter, embodiments of a radar apparatus according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram of a radar apparatus according to an embodiment of the present invention. In FIG. 1, the radar apparatus according to the present embodiment includes a VCO (voltage controlled oscillator) 101, an amplifier 102, and a transmission antenna 103 in a transmission system Tx, and reception antennas 104-1 to 104-104 in five reception systems Rx1 to Rx5, respectively. -5, RF amplifiers 105-1 to 105-5, mixers 105-1 to 106-5, BB amplifiers 107-1 to 107-5, and bandpass filters 108-1 to 108-5, and a sample hold circuit 109-1 to 109-5, a switching device 110, an A / D converter 111, and a signal processing device 112 are provided.

FIG. 2 shows a timing chart of various signals in the radar apparatus of this embodiment. The function and operation of each component will be described in detail with reference to FIG.
First, in the transmission system Tx, a VCO (Voltage Controlled Oscillator) 101 generates a high-frequency signal in the millimeter wave band that is modulated so that the frequency repeats linear increase and decrease with time, for example, and transmits a transmission signal and a reception signal. The power is distributed to the local signal L to the systems Rx1 to Rx5 and output. After the transmission signal thus modulated by the VCO 101 is amplified by the amplifier 102, a transmission wave is radiated through the transmission antenna 103.

      Next, in the reception systems Rx1 to Rx5, the reflected waves of the transmission waves radiated from the transmission system Tx are simultaneously received by the plurality of reception antennas 104-1 to 104-5 constituting the array antenna. The received signal is amplified by the RF amplifiers 105-1 to 105-5, and then mixed with a local signal having the same frequency as the transmission signal from the VCO 101 by the mixers 105-1 to 106-5 to obtain a beat signal.

  Further, the beat signal is amplified to a predetermined level by the BB amplifiers 107-1 to 107-5, and is filtered to a predetermined frequency band by the band pass filters 108-1 to 108-5 to be beat signals B1 to B5.

  Next, the sample hold circuits 109-1 to 109-5 sample and hold the beat signals B1 to B5 by timing control based on the sample hold signal SH1 from the signal processing device 112 (see FIG. 2A). That is, the beat signals B1 to B5 are sampled during a period in which the sample hold signal SH1 is at the H level (S in FIG. 2A), and the signal level of the beat signals B1 to B5 at the sampling timing is the H level. Immediately after that, the sample hold signal SH1 is held (held) for a period of time at L level (H in FIG. 2A). 2B to 2F show beat signals B1 to B5 (broken lines in the figure) and sampled and held beat signals BH1 to BH5 (solid line in the figure).

  Next, in the switcher 110, the beats sampled and held in accordance with the switcher selection signal SEL1 (see FIG. 2 (g)) from the signal processor 112 during the hold period of the sample hold circuits 109-1 to 109-5. The signals BH1 to BH5 are sequentially selected and output. In the A / D converter 111, the selected beat signals BH1 to BH5 are sequentially converted into digital signals at the rising timing of the A / D conversion clock ADCL1 (see FIG. 2H) from the signal processing device 112. .

  Furthermore, in the signal processing device 112, digital beam forming processing (weighting including phase calculation is added to each of the beat signals B1 to B5 and added based on the amplitude and phase information of each beat signal converted into a digital signal) ) To form a beam.

  As described above, in the radar apparatus of the present embodiment, the transmission system Tx that transmits the transmission wave, the five reception systems Rx1 to Rx5 that receive the reflection wave of the transmission wave, the transmission signal and the reception wave of the transmission wave A sample-and-hold circuit 109-1 to 109-5 that samples the signal obtained by mixing the received signal and the received signal at a predetermined timing and fixes the sampled signal at the sampled level for a predetermined period, and the sample-hold circuits 109-1 to 109-5. A switch 110 and an A / D converter 111 that sequentially convert outputs into digital signals; and a signal processing device 112 that determines sampling timing and performs digital beam forming processing based on the output of the A / D converter 111. Therefore, one A / D converter can be used without requiring as many expensive A / D converters as the number of receiving systems. Can, the cost of the radar apparatus can be made inexpensive. Further, by adjusting the sampling timing in the sample hold circuits 109-1 to 109-5 to the same timing by the sample hold signal SH1, the signal processing device 112 performs the digital beam forming process based on the mixed signal at the same time. Therefore, it is possible to reduce the time error included in the signal amplitude and phase information and perform accurate processing.

      In the embodiment described above, the configuration of one transmission system Tx and five reception systems Rx1 to Rx5 is shown. However, five transmission systems Tx are combined with five reception systems Rx1 to Rx5. The same effect can be achieved by the configuration of the transmission / reception system. One of the configurations is selected in consideration of the purpose of use of the radar device and the arrangement of the radar device.

  In the description of the embodiment, the sampling timings in the sample hold circuits 109-1 to 109-5 are the same. However, it is also possible to adjust the timing by independently performing timing control. In particular, in the case of a configuration with N transmission / reception systems, there may be a time error due to other factors such as a phase shift of the local signal of the VCO and a phase shift due to the distribution of the local signal. Correction can be made by adjusting the timing.

It is a block diagram of the radar apparatus which concerns on one Example of this invention. It is a timing chart of various signals in a radar apparatus of an example. It is a block diagram of the radar apparatus which concerns on the prior art example 1. FIG. It is a block diagram of the radar apparatus which concerns on the prior art example 2.

Explanation of symbols

Tx transmission system (transmission means)
Rx1 to Rx5 reception system (reception means)
101 VCO (Voltage Controlled Oscillator)
DESCRIPTION OF SYMBOLS 102 Amplifier 103 Transmission antenna 104-1 to 104-5 Reception antenna 105-1 to 105-5 RF amplifier 106-1 to 106-5 Mixer 107-1 to 107-5 BB amplifier 108-1 to 108-5 Band pass filter 109-1 to 109-5 Sample hold circuit 110 Switch (A / D conversion means)
111 A / D converter (A / D conversion means)
112 Signal processor B1 to B5 Beat signal BH1 to BH5 Sampled and held beat signal SH1 Sample and hold signal ADCL1 A / D conversion clock SEL1 Switch selection signal

Claims (4)

A transmission means for transmitting a transmission wave;
N receiving means for receiving the reflected wave of the transmission wave (N is a positive integer of 2 or more);
N sample-and-hold means for sampling a signal obtained by mixing the transmission signal of the transmission wave and the reception signal of the reception wave at a predetermined timing, and fixing the sampled level at a predetermined period.
A / D conversion means for sequentially converting the outputs of the N sample and hold means into digital signals;
Signal processing means for determining a sampling timing in the N sample hold means and performing digital beam forming processing based on an output of the A / D conversion means;
A radar apparatus comprising: N transmission / reception means for transmitting a transmission wave and receiving a reflection wave of the transmission wave (N is a positive integer of 2 or more);
N sample-and-hold means for sampling a signal obtained by mixing the transmission signal of the transmission wave and the reception signal of the reception wave at a predetermined timing, and fixing the sampled level at a predetermined period.
A / D conversion means for sequentially converting the outputs of the N sample and hold means into digital signals;
Signal processing means for determining a sampling timing in the N sample hold means and performing digital beam forming processing based on an output of the A / D conversion means;
A radar apparatus comprising:   The radar apparatus according to claim 1, wherein the N sample and hold units sample at the same timing. The transmission unit or the transmission unit of the transmission / reception unit transmits the transmission wave based on a transmission signal having a predetermined frequency, and the reception unit or the reception unit of the transmission / reception unit receives the reflected wave. Is mixed with a local signal having the same frequency as the transmission signal to obtain a beat signal, and the N sample-and-hold means sample the beat signal at a predetermined timing and fix it at the sampled level for a predetermined period. The radar device according to any one of claims 1 to 3, wherein

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