JP2004317524A - Radar system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radar system which only requires establishment of one front end common to each antenna, without the need for setting up RF receiver circuit for each antenna. <P>SOLUTION: In this radio system, a front end which time-division amplifies any sequentially-input signal received by each antenna, as well as frequency-converting it into an intermediate frequency signal, is provided commonly for each antenna. Each antenna is cyclically connected to the front end at a defined switching frequency, the intermediate frequency signal output from the front end is input to analog-to-digital (AD) converter provided for each antenna to be AD converted through an intermediate frequency filter, and then phase or amplitude of the signal output from each AD converter is adjusted into a composite signal, to detect an object from the desired direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a radar device having a plurality of antennas and having a function of electronically controlling antenna beams, and more particularly to a radar device in which only one front end is required to be provided in common for each antenna.

Conventional methods for controlling antenna beams include: (1) mechanically changing the direction of the antenna, (2) switching between multiple antennas with different directivities, or (3) arraying a large number of antennas. There is a method of electrically combining the radiation patterns of those antennas.
In mechanical beam control, a driving device is required, so that the device becomes large.If the weight of the transceiver with the integrated antenna is heavy, the required accuracy can not be obtained unless the driving device is complicated and large. Due to disadvantages such as the inability to perform high-speed sweeping, electronic beam control means is often selected.

  As the electronic beam control, there are a method of switching a plurality of antennas having different directivities as described above, and a method of arraying a plurality of antennas and electrically combining the radiation patterns of the antennas. The former is called a beam switch method. In the latter case, a typical method is an active phased array antenna in which the phases and amplitudes of signals transmitted to individual antennas or signals received from individual antennas are adjusted and then combined. Here, a radar apparatus provided with a receiving apparatus capable of controlling these antenna beams will be considered.

  The beam-switch type receiving apparatus is composed of (1) a switch directly connected to an antenna, switching a plurality of antennas, and connecting to a subsequent radio frequency band receiving apparatus (hereinafter referred to as an RF receiving circuit), or (2) It is composed of a plurality of antennas, an RF receiving circuit directly connected to each antenna, and a switch for switching between these RF receiving circuits and connecting to a subsequent processing device. In the beam switch method, the individual antennas have different directivities, and the direction in which the radar detects is controlled by switching between them using an electronic switch. The RF receiving circuit performs low noise amplification and frequency conversion of the received signal. In particular, when the noise characteristics of the receiver are taken into consideration, the latter configuration (1) in which the antenna and the RF receiving circuit are directly connected is adopted.

  As shown in FIG. 24, an active phased array type receiving device includes a plurality of array antennas 1a to 1n, an RF receiving unit 2 having RF receiving circuits 2a to 2n directly connected to the respective antennas, and an RF receiving circuit 2a. 1 to 2n. Each of the RF receiving circuits 2a to 2n has a function of amplifying and frequency converting a signal received from each antenna, and a function of performing phase shift and amplitude adjustment corresponding to a desired beam pattern.

In the RF receiving section 2, 2a to 2n are RF receiving circuits directly connected to the respective antennas, 7 is a phase control circuit for determining a phase shift amount, 8 is an amplitude control circuit for determining an amplitude adjustment amount, and 9 is a local oscillator. Each RF receiver circuit 2a~2n includes an RF amplifier 3a~3n for low-noise amplifying the RF signal received by the antenna, the phase shifter in the low-noise amplified RF signal subjected to phase shift of a predetermined amount phi ₁ to [phi] _N 4a to 4n, amplitude adjustment units 5a to 5n for adjusting the amplitude of the signal output from the phase shifter, and a mixer (frequency) for converting the RF signal output from each amplitude adjustment unit into an intermediate frequency signal (IF signal) Converters) 6a to 6n. Phase control circuit 7 and the amplitude control circuit 8 a desired beam pattern phase shift corresponding to the phase shift amount so as to perform the amplitude adjustment phi ₁ to [phi] _N, each phase shift to determine the amplitude adjustment values A ₁ to A _N And input to the amplitude adjusters 5a to 5n. The local oscillator 9 oscillates at a predetermined frequency and inputs a local oscillation signal to each mixer. The adder 10 combines the outputs of the mixers and inputs the combined output to a processing unit (not shown).
In the active phased array type receiving apparatus, the combined radiation pattern can be controlled by controlling the amount of phase shift and the amount of amplitude adjustment of each antenna reception signal, thereby changing the radar detection direction. Further, by continuously changing the amount of phase shift and the amount of amplitude adjustment, continuous control of the detection direction is possible.

  The above is an example of the analog configuration, but there is also a technology called DBFN (Digital Beam Forming Network) that makes full use of digital technology and has both digital and analog characteristics. The DBFN has a configuration similar to the active phased array system as shown in FIG. The difference from the active phased array system is that (1) the frequency converters 6a to 6n and the local oscillator 9 are arranged after the low noise amplifiers 3a to 3n, and (2) the output signals of the frequency converters 6a to 6n. (3) A / D converters 102a to 102n for converting IF filter outputs into digital, and (4) DSP for phase shift control / amplitude control. And so on by digital processing.

  In the DBFN receiver, signals received from the antennas 1a to 1n are amplified by low-noise amplifiers 3a to 3n and then frequency-converted by frequency converters 6a to 6n. IF filters 101a to 101n extract intermediate frequency components from the output of each frequency converter, AD converters 102a to 102n convert IF signals into digital data, and a digital signal processor (DSP) adjusts the phase amount and amplitude by digital processing. Is performed, and the adder 10 performs vector synthesis of each signal. As described above, a desired beam pattern is formed, and the detection direction is controlled. This is exactly the same principle as the active phased array system described above.

  Also, as shown in FIG. 26, a plurality of phase shift / amplitude adjusting means 103a to 103m are provided, and digital data output from the AD converters 102a to 102n is branched and input to each phase shift / amplitude adjusting means 103a to 103m. The phase shift / amplitude adjusting means 103a to 103m perform separate phase shifts and amplitude adjustments on the respective branch signals, and separately synthesize and output the signals. In this way, a plurality of radiation patterns can be formed at the same time, and signals from a plurality of directions can be simultaneously distinguished and obtained. In the configuration of FIG. 26, the active phased array system and the beam switch system are simultaneously realized. The use of digital circuits depends on the ease of design and manufacture.

In addition to the active phased array method, there is a monopulse method as a method for detecting the direction of a target. The monopulse system differs from the active phased array system in that the reflected power from the target is received by two antennas and the phase or amplitude of the reflected power received by the two antennas is compared to estimate the direction of the target (signal arrival direction). ,To detect.
FIG. 27 is a configuration diagram of a receiving unit in a monopulse type radar device, where 110a and 110b are antennas, 111a and 111b are low-noise RF amplifiers, 112a and 112b are local oscillators, 113a and 113b are frequency converters, 114a and 114b. 114b is an IF filter, 115a and 115b are AD converters that convert IF signals into digital signals, 116 is a phase comparison circuit that compares phases of reception signals of two antennas, and 117 is an amplitude of reception signals of two antennas. An amplitude comparison circuit 118 is an arrival direction estimation circuit that estimates the direction of a target (signal arrival direction) based on the phase difference or the amplitude difference.

  Although the two receiving antennas 110a and 110b are directed in substantially the same direction, their installation positions are slightly different. For this reason, the radiation beam patterns overlap slightly offset. If the target is equidistant from the two antennas, the phases of the received signals reaching both antennas 110a and 110b are equal. If the target is closer to either antenna, the position of the received signal reaching the respective antennas is equal. The signal arrival direction (direction of the target) can be estimated from the phase difference and the antenna interval. The monopulse method estimates the direction of a target based on this principle.

  The beam switching method, which is an antenna switching method, requires a plurality of independent antennas. These beam widths are required to be relatively narrow, and depending on the use of the radar, beam widths and antenna gains are often required to be uniform. For this reason, a plurality of antennas having a relatively large area are required, the area occupied by the antenna is several times larger than that of a radar apparatus without beam control or a radar apparatus of an active phased array system, and the manufacturing cost of the antenna part is increased. Further, in the beam switch method, since the control of the detection direction is performed discretely by switching a plurality of antennas having different directivities, the target angular resolution is limited by the beam width of each antenna and the number of antennas. .

In the active phased array system and the DBFN system, a plurality of antenna radiation patterns are combined to obtain one radiation pattern having a desired directivity. Therefore, it is not necessary to increase the size of the antenna as in the beam switch system. Further, by continuously changing the amount of phase shift and the amount of amplitude adjustment as described above, continuous control of the detection direction is possible, and the angular resolution can be increased. However, in these systems, individual RF receiving circuits are required for a plurality of antennas, which increases the size and complexity of the device and increases the manufacturing cost. In addition, manufacturing variations in circuit-specific amplitude and phase characteristics, and manufacturing variations in parameters and temperature and frequency characteristics become more apparent as the frequency increases. For this reason, special consideration is required in the design of the device, and in some cases, it is necessary to provide a compensation means and an adjustment circuit. Further, the multi-beam DBFN system having a plurality of beam combining means (FIG. 26) has a problem that the apparatus becomes more complicated.
The monopulse system also requires an individual RF receiving circuit for each antenna, and has the same problem as the active phased array system.

From the above, it is an object of the present invention to provide a radar device which does not need to provide an RF receiving circuit (front end) for each antenna and only needs to provide one front end in common for each antenna. .
Another object of the present invention is to provide a radar apparatus in which only one front end is required to be provided in common for each antenna with a configuration in which necessary components are reduced.
Another object of the present invention is to provide a radar apparatus in which even when an antenna is shared for transmission and reception, it is only necessary to provide one front end for each antenna.

The radar apparatus according to the first aspect of the present invention includes a plurality of antennas, an adjustment circuit provided for each antenna, and adjusting a phase or an amplitude of an input signal, and a synthesizing circuit for synthesizing the phase or amplitude adjusted signals. A radar device having an array antenna configuration, the radar device comprising: (1) a front end that is provided in common for each antenna and amplifies each antenna reception signal sequentially input and frequency-converts the signal to an intermediate frequency signal; (2) A switch that cyclically connects each antenna to the front end at a predetermined switching frequency, (3) an intermediate frequency filter that passes an intermediate frequency signal output from the front end, (4) provided corresponding to each antenna, An AD converter for AD-converting the output of the intermediate frequency filter, (5) when the reception signal of the i-th antenna is input to the front end, the i-th antenna And a sampling control circuit for sampling the output of the intermediate frequency filter by an AD converter corresponding to the above, and performing AD conversion. To detect the target.
With this configuration, the output of the A / D converter becomes equal to the output of the frequency converter of the first aspect sampled, and the second switch and the frequency converter can be omitted as compared with the first aspect of the invention. The number of components can be reduced.

  A radar device according to a second aspect of the present invention includes a delay circuit for making the AD conversion timing coincide with the preceding stage of the AD converter. By providing the delay circuit, the received signals sampled at the same timing can be A / D converted and processed, so that the accuracy of target detection can be improved.

According to a third aspect of the present invention, there is provided a radar apparatus comprising: a plurality of antennas; an adjustment circuit provided for each antenna for adjusting the phase or amplitude of an input signal; and a synthesis circuit for synthesizing each phase or amplitude adjusted signal. The radar device having the array antenna configuration includes: (1) a front end that is provided commonly to each antenna and amplifies each antenna reception signal sequentially input and frequency-converts the signal into an intermediate frequency signal; (2) a predetermined switching frequency. A switch for cyclically connecting each antenna to the front end, (3) an AD converter for AD converting an intermediate frequency signal output from the front end, (4) a frequency obtained by multiplying a switching frequency by the number of the plurality of antennas Performs an A / D converter to sample / AD convert the output of the intermediate frequency filter, and a reception signal of the i-th antenna is input to the front end. Means for storing the A / D conversion output during the operation as a signal corresponding to the i-th antenna. The output signal of the A / D converter corresponding to each antenna is phase-adjusted or amplitude-adjusted and combined to obtain a desired direction. Detect targets from.
With this configuration, it is only necessary to provide one AD converter and one phase / amplitude adjusting means in common for each antenna, so that it is possible to further reduce the number of parts used and simplify the configuration.

According to a fourth aspect of the present invention, there is provided a radar device for comparing two antennas, a comparison unit for comparing the phases and / or amplitudes of the reflection signals arriving at the two antennas, and an arrival direction estimation unit for estimating the arrival direction of the reflection signal based on the comparison result. The radar apparatus further includes (1) a front end provided common to each antenna, amplifying each antenna receiving signal sequentially input and frequency-converting the signal into an intermediate frequency signal, (2) ) A switch for alternately connecting each antenna to the front end at a predetermined switching frequency, (3) an AD converter provided for each antenna and AD converting an intermediate frequency signal output from the front end, (4) ) When the reception signal of the i-th antenna is input to the front end, the A / D converter corresponding to the i-th antenna performs sampling and performs AD conversion. A sampling control circuit is provided, and the direction of arrival of the reflected signal is estimated by comparing the phase or amplitude of each AD converter output signal as the reflected signal.
With this configuration, the output of the A / D converter is equal to the output of the frequency converter according to claim 11 sampled, so that the second switch and the frequency converter can be omitted, and the number of components can be reduced. .

According to the first aspect of the present invention, since the AD converter corresponding to each antenna samples the antenna reception signal and performs AD conversion at the antenna selection timing, the number of components can be reduced.
According to the second aspect of the present invention, since the delay circuit for matching the A / D conversion timing is provided in the preceding stage of the A / D converter, the received signals sampled at the same timing can be A / D converted and processed, so that the accuracy of target detection can be improved. Can be improved.
According to the invention of claim 3, one A / D converter is provided in common for each antenna, and the A / D converter is used for sampling / AD conversion of the reception signal of each antenna in a time-division manner. And the configuration can be simplified.
According to the fourth aspect of the present invention, in the monopulse type radar device, the AD converter corresponding to each antenna samples the antenna reception signal and performs AD conversion at the antenna selection timing, so that the number of components is reduced. be able to.

The radar apparatus of the present invention is provided in common with each antenna element of an array antenna, amplifies each antenna reception signal sequentially input, and converts the frequency into an intermediate frequency signal, and front-ends each antenna element at a predetermined switching frequency. , An intermediate frequency filter that passes an intermediate frequency signal output from the front end, an AD converter that is provided corresponding to each antenna, and performs AD conversion on the output of the intermediate frequency filter, an i-th antenna When the received signal is input to the front end, a sampling control circuit that performs an AD converter corresponding to the i-th antenna and samples and converts the intermediate frequency filter output into an analog-to-digital converter is provided corresponding to each antenna. An adjustment circuit for adjusting the phase or amplitude of the output signal of the AD converter, And a combining circuit for combining the signals that have been adjusted.
According to the radar device of the present invention, all the antenna elements of the array antenna are switched at a high switching frequency, and the received signal of each obtained antenna element is AD-converted in synchronization with the switching frequency and shaped into a waveform that can be combined with the array. Then, the target is detected based on the synthesized signal.

(A) Configuration FIG. 1 is a configuration diagram of the radar apparatus of the first embodiment, mainly showing a receiving system, and having a DBFN type receiving configuration.
In the figure, 11 _{1 to} 11 _N are a plurality of antennas for receiving reflected power from a target, 12 is a first switch, and each antenna has a frequency fs much higher than the baseband frequency fb as shown in FIG. To connect to the front end cyclically. Reference numeral 13 denotes a front end provided commonly to the antennas, and (1) an RF amplifier 13a for amplifying the received signal of each antenna with low noise; and (2) a frequency f when the carrier frequency is fc and the baseband frequency is fb. A local oscillator 13b that outputs a local oscillation signal of _LO (= fc−fb); and (3) an RF signal obtained by mixing a local oscillation signal of frequency f _LO (= fc−fb) with the RF signal output from the RF amplifier. (Frequency converter) 13c for converting the frequency of the signal into an intermediate frequency signal.

Reference numeral 14 denotes a second switch which switches in synchronization with the first switch 12 and, when a reception signal of the i-th antenna is input to the front end 13, converts the front-end output to a frequency conversion corresponding to the i-th antenna. 2, an oscillator for outputting a signal of frequency N · fs, and 16 a switch control unit, which receives a signal of frequency N · fs to generate antenna selection signals S _{1 to} S _N shown in FIG. And controls the first and second switches 12, 14.
17 _{1 to} 17 _N are provided corresponding to the respective antennas, remove higher harmonic components and lower frequency components from a signal input from the front end 13 via the second switch 14, and pass a desired intermediate frequency component. IF filter 18 is a low pass filter for converting the square wave frequency fs to the local oscillation signal of a sine wave, 19 ₁ ~ 19 _N are corresponding local oscillation signal to the IF signal output from IF filter 17 ₁ to 17 _N (Frequency converter) that mixes the signals into different intermediate frequency signals or baseband signals.

20 ₁ to 20 _N is an AD converter for converting the respective frequency converter output to a digital, 21 ₁ through 21 _N phase shifter for applying a phase shift of predetermined amount phi ₁ to [phi] _N to the input signal, 22 ₁ through 22 _N Is an amplitude adjustment unit for adjusting the amplitude of the signal output from the phase shifter, and 23 and 24 are a phase control circuit and an amplitude control circuit, respectively, which perform phase shift and amplitude adjustment corresponding to a desired beam pattern. used to input shift phi ₁ to [phi] _N, the amplitude adjustment value a ₁ was determined to a _N are each phase shifter 21 ₁ through 21 _N, the amplitude adjustment unit 22 ₁ through 22 _N, 25 each amplitude adjuster 22 ₁ an adder for combining and outputting the signals output from the through 22 _N.

(B) Operation Each RF signal received by each of the antennas 11 _{1 to} 11 _N is cyclically selected by the first switch 12 at the frequency fs and input to the front end 13, and the output of the front end is synchronized with the first switch. and it is selected in the second switch 14 for switching operation, through the IF filter 17 ₁ to 17 _N is input to the frequency converter 19 ₁ ~ 19 _N. That is, the second switch 14 performs a switching operation in synchronization with the first switch 12, and when the reception signal of the ith antenna 11 i is input to the front end 13, converts the front end output to the frequency conversion corresponding to the ith antenna. Device 19i.

Be intermittently selecting the RF signal received by the antenna 11 ₁ to 11 _N (carrier signal) in the frequency fs is equivalent to that of the RF signal (carrier signal) in the frequency fs amplitude modulated. Therefore, if fc is the frequency of the carrier signal (RF signal), fb is the frequency of the baseband signal carried by the carrier signal, f _LO (= fc−fb) is the oscillation frequency of the local oscillation signal, and fs is the switching frequency, The frequency components shown by the spectrum in FIG. 3A are generated by the switching operations of the first and second switches 12 and 14. And inputs this signal to the frequency f _LO (= fc-fb) of the local oscillation signal when mixed in a mixer 13c FIG 3 (b) to the IF filter 17 _1-17 a signal having a spectrum distribution is generated showing _N .

Each IF filter 17 ₁ to 17 _N selects the IF signal (intermediate frequency signal fs ± fb) outputs contained in the intermediate frequency band indicated by the dotted line in FIG. 3 (b), the frequency converter 19 ₁ ~ 19 _N the signal input from the IF filter 17 ₁ to 17 _N, a mixture of local oscillation signal of frequency fs to be output from the filter 18, and outputs the demodulated baseband signal shown in Figure 3 (c).
AD converter 20 ₁ to 20 _N convert the baseband signal demodulated by the frequency converter 19 ₁ ~ 19 _N to digital data. The phase control circuit 23 and the amplitude control circuit 24 perform the phase shift and amplitude adjustment corresponding to the desired beam pattern, that is, the phase shift amounts φ _{1 to} φ _N so as to detect a target from a desired direction. , set by determining the amplitude control value a ₁ to a _N respective phase shifters 21 ₁ through 21 _N, the amplitude adjustment unit 22 ₁ through 22 _N.

Each phase shifter 21 ₁ through 21 _N, the amplitude adjusting unit 22 ₁ through 22 _N are AD converters 20 ₁ to 20 the phase shift amount in the digital data input from the _{N φ 1 ~φ N,} amplitude adjustment values A ₁ to A _N subjecting the phase shift, the amplitude adjustment, the adder 25 is input to the subsequent processing unit (not shown) by combining the signals output from the amplitude adjustment unit 22 ₁ through 22 _N, the processing apparatus is a target substance detecting process I do. Thereafter, the direction of the target can be detected by sequentially changing the detection direction and repeating the above control.
As described above, according to the first embodiment, in the radar device having the array antenna configuration, it is only necessary to provide one front end 13 in common for each antenna. Compensation means and an adjustment circuit can be eliminated.

(C) First Modification FIG. 4 shows another configuration example of the amplitude control of the first embodiment, and the same parts as those of the first embodiment in FIG. In the first embodiment, the amplitude is adjusted by applying the amplitude adjustment values A _{1 to} A _N to the baseband digital data. However, in the first modified example of FIG. 4, the amplitude is adjusted by adjusting the on-time of the first and second switches 12, 14.

When the amplitude weighting to the amplitude control circuit 24 'each antenna 11 ₁ to 11 _N, as shown in FIG. 5 is input, the switch control unit converts the amplitude weighting value to the switch-on time W ₁ to _W-N 16 '. Thus, the switch control unit 16 'is the pulse width W ₁ to W-antenna selection signals S ₁ of _N at the frequency fs as shown in FIG. 6' generates to S _N '. The first and second switches 12 and 14 select the respective antennas based on the antenna selection signals S ₁ ′ to S _N ′, input the front end to the front end, and input the front end output to the frequency converter. Control when you are. Since the pulse width and amplitude are equivalent, the amplitude is adjusted according to the pulse width W ₁ to _W-N. That is, the amplitude control circuit 24 'connects the antennas 11 _{1 to} 11 _N to the front end 13 and connects the front end outputs to the frequency converters 19 _{1 to} 19 _N corresponding to the antennas. W _{1 to} W _N are adjusted to have values corresponding to the amplitude adjustment values A _{1 to} A _N. According to this modification, the amplitude can be adjusted only by changing the ON time width of the switch, and the configuration can be simplified.

(D) The output of the frequency converter 19 ₁ ~ 19 _N of the second modified example first embodiment, the phase and amplitude of the local oscillation signal also reflected. In other words, the same effect as the phase shift and amplitude adjustment of the intermediate frequency signal or the baseband signal can be obtained by adjusting the phase shift and amplitude of the local oscillation signal. Therefore, in the second modification, the phase shift amount and the amplitude adjustment value of the local oscillation signal of the frequency converters 19 _{1 to} 19 _N are controlled so that a desired beam pattern can be obtained, that is, from a desired direction. The target can be detected.
FIG. 7 is a configuration diagram of a second modified example, and the same parts as those in the first embodiment of FIG. 1 are denoted by the same reference numerals. Local oscillation signal of the frequency converter 19 ₁ ~ 19 _N is the output signal of the low-pass filter 18. Therefore, in the second modification, the phase shifters 21 ₁ to 21 for controlling the phase and amplitude of its output to the output side of the low-pass filter 18 _N, the amplitude adjustment unit 22 ₁ through 22 _N provided. The low-pass filter 18 receives a rectangular wave having a frequency fs from the switch control unit 16.

Phase control circuit 23, the amplitude control circuit 24 is the desired beam pattern phase shift corresponding to the phase shift amount so as to perform the amplitude adjustment phi ₁ to [phi] _N, each phase shift to determine the amplitude adjustment values A ₁ to A _N vessel 21 ₁ through 21 _N, to set the amplitude adjustment unit 22 ₁ through 22 _N. Each phase shifter 21 ₁ through 21 _N are subjected to a phase shift of predetermined amount phi ₁ to [phi] _N to the local oscillation signal, the amplitude adjustment value A ₁ to the signal amplitude adjustment part 22 ₁ through 22 _N are output from the phase shifter subjected to the amplitude adjustment of ~A _N. As a result, the amount of phase shift to the output of the frequency converter _{19 1 ~19 N φ 1 ~φ N} , it reflects the amplitude adjustment values A ₁ to A _N, the desired beam pattern, i.e., the target from a desired direction Be able to detect.

Figure 8 is a third modification example in which only the amplitude adjustment unit 22 ₁ through 22 _N for controlling the output amplitude at the output side of the low-pass filter 18, the same reference numerals in the first embodiment and the same parts in FIG. 1 It is attached.
Figure 9 is a fourth modified example in which only the phase shifter 21 ₁ through 21 _N for controlling the output phase to the output side of the low-pass filter 18, the same reference numerals in the first embodiment and the same parts in FIG. 1 It is attached.

(A) Configuration of Second Embodiment FIG. 10 is a configuration diagram of a radar apparatus of a second embodiment, mainly showing a receiving system, and the same parts as those of the first embodiment are denoted by the same reference numerals. .
The first embodiment to remove the second switch 14 and IF filter 17 ₁ to 17 _N frequency converter 19 ₁ ~ 19 _N in (FIG. 1), connecting the front-end output to the AD converter 20 ₁ to 20 _N. Further, a sampling control circuit 31 is provided, and when a reception signal of the i-th antenna 11i is input to the front end 13, only the AD converter 20i corresponding to the i-th antenna samples the output of the front end and performs AD conversion. Control.

Figure 11 is a time chart of the sampling signal AD1～AD _N antenna selection signals S ₁ to S _N and the AD converter 20 ₁ to 20 _N for selecting antennas 11 ₁ to 11 _N, the antenna selection signal Si (i = 1 To N), the sampling signal ADi rises, and the AD converter 20i samples the front end output signal for a predetermined time and performs AD conversion.
With the configuration described above, the output of the AD converter 20 ₁ to 20 _N is equal to that the AD conversion by sampling the output of the frequency converter 19 ₁ ~ 19 _N of the first embodiment. Accordingly, by supplying the output of the AD converter 20 ₁ to 20 _N phase shifters 21 ₁ through 21 _N, the amplitude adjustment unit 22 ₁ through 22 _N, the received signal from each antenna so as to form a desired antenna radiation pattern If the phase shift amount and the amplitude adjustment amount are controlled and these signals are combined by the adder 25, the target can be detected from a desired direction.

According to the second embodiment, the sampling control circuit 31 in comparison with the first embodiment is increased, can omit the second switch 14 and the frequency converter 20 ₁ to 20 _N, it is possible to reduce the component.
In the second embodiment, the IF filters 17 _{1 to} 17 _N can be shared by one IF filter. That is, the front end 13 connected to one of the IF filter can be configured to connect the IF filter output to the AD converter 20 ₁ to 20 _N.

(B) First Modification FIG. 12 shows a first modification of the second embodiment, in which the same parts as those of the second embodiment in FIG. Differs from the second embodiment in that a delay circuit 32 ₁ ~32 _N-1 between the front end of each AD converter 20 ₁ ~20 _N-1. By providing the delay circuit 32 ₁ ~32 _N-1, the sampling and the AD conversion timing of the AD converter 20 ₁ to 20 _N can be matched, it is possible to improve the accuracy of direction finding of targets.

(C) Second Modification FIG. 13 shows a second modification of the second embodiment, in which the same parts as those of the second embodiment in FIG. FIG. 14 is a time chart for explaining the operation of the second modification.
The second modified example is different from the second embodiment in that:
(1) A single AD converter 20 for each antenna
(2) The AD converter 20 samples the output with a sampling clock having the same frequency as the switching frequency N · fs of the switch 12 and performs AD conversion.
(3) A / D conversion data at each sampling clock of the A / D converter 20 is input to the data rearrangement device 41.
(4) the digital data in which the data rearrangement unit 41 are sequentially inputted as shown in FIG. 14, the first antenna 11 ₁ of the first data → second antenna 11 ₂ of the first data → · · · → the N antenna _11N first data → first antenna 11 ₁ second data → second antenna 11 ₂ second data →... → N-th antenna 11 _N second data →. Point,
(5) The data rearrangement device 41, the phase control circuit 23, and the amplitude control circuit 24 are constituted by a DSP (Digital Signal Processor), and the phase shift and the amplitude adjustment of the phase shift amounts φ _{1 to} φ _N are performed on each antenna reception signal by the DSP processing. The point is that the amplitudes of the values A _{1 to} A _N are adjusted and synthesized.

In the second modification, the phase shift of the received signal from each antenna so as to form a desired antenna radiation pattern phi ₁ to [phi] _N, to control the amplitude adjustment amount A ₁ to A _N, and synthesizing these signals Output enables detection of a target from any direction.

(A) Configuration FIG. 15 shows a monopulse radar device according to the third embodiment, and particularly shows a configuration of a receiving system.
51 _{1-51 2} first, second antenna for receiving a reflected power from the target, 52 is a first switch, the baseband frequency the first at a much higher switching frequency fs than fb, the second An antenna that alternately selects an antenna and connects it to the front end, 53 is a front end provided commonly to the first and second antennas, and (1) an RF amplifier 53a that amplifies each antenna reception signal with low noise; 2) When the carrier frequency is fc and the baseband frequency is fb, a local oscillator 53b that outputs a local oscillation signal having a frequency f _LO (= fc−fb), and (3) a frequency is applied to the RF signal output from the RF amplifier. A mixer (frequency converter) 53c for mixing the local oscillation signal of f _LO (= fc−fb) and converting the frequency of the RF signal into an intermediate frequency signal is provided.

54 is a second switch, in synchronization with the first switch 52 is switched, when the first or second antenna 51 _1, 51 ₂ of the received signal is input to the front end 53, the front end output Is connected to a frequency converter corresponding to an antenna, 55 is an oscillator that outputs a signal having a frequency of 2 · fs, and 16 is a switch control unit, which receives a signal having a frequency of 2 · fs and receives antenna selection signals S _{1 to} S ₂ (see FIG. 2, where N = 2) to control the first and second switches 52 and 54.
57 _{1-57 2} is provided corresponding to each antenna 51 _{1-51 2,} harmonic component from the signal input from the front end 53 via the second switch 14, to remove low-frequency components, the desired intermediate IF filter that passes the frequency component, a low-pass filter for converting the square wave frequency fs to the local oscillation signal of the sine wave 58, 59 _{1-59 2} outputs from the corresponding IF filter 17 ₁ to 17 ₂ IF A mixer (frequency converter) that mixes a signal with a local oscillation signal (low-pass filter output) and converts the frequency to another intermediate frequency signal or a baseband signal.

60 ₁ to 60 ₂ AD converter for converting the respective frequency converter output to a digital, 61 a phase comparator circuit for comparing the phase of the received signals of the two antennas, 62 compares the amplitude of the received signals of the two antennas The amplitude comparison circuit 63 is an arrival direction estimation circuit that estimates the direction of the target (signal arrival direction) based on the phase difference or the amplitude difference. Note that both the phase comparison and the amplitude comparison are not necessarily required, and a configuration having only one of the phase comparison circuit and the amplitude comparison circuit may be employed.
₁ two receiving antennas 51, 51 ₂ is directed to substantially the same direction, but the installation position is slightly different. For this reason, the radiation beam patterns overlap slightly offset. If the target is from the two antennas equidistant, the received signal phase to reach both the antennas 51 _1, 51 ₂ are equal, if it displaced in whichever of the antenna, the received signal reaching the respective antenna The direction of arrival of the signal (the direction of the target) can be estimated from the phase difference and the antenna spacing.

(B) Operation Each RF signals received by the antenna 51 _{1-51 2} is selected alternately at a frequency fs by the first switch 52 is inputted to the front end 53, the output of the front end is synchronized with the first switch Te is selected in the second switch 54 for switching operation, through the IF filter 57 _{1-57 2} input to the frequency converter 59 _{1-59 2.} That is, the second switch 54 performs a switching operation in synchronization with the first switch 52, when the first or second antenna 51 _1, 51 ₂ of the received signal is input to the front end 53, the front end output The first and second antennas 51 ₁ and 51 are connected to frequency converters 59 ₁ and 59 ₂ .

Antenna 51 ₁ to 51 RF signal (carrier signal) received by ₂ to intermittently selected at a frequency fs is equivalent to that of the RF signal (carrier signal) in the frequency fs amplitude modulated. Accordingly, the switching operation of the first and second switches 52 and 54 generates a frequency component shown by the spectrum in FIG. The signal frequency f _LO local oscillation signal (= fc-fb) is input signal having a spectrum distribution is generated in the IF filter 57 _{1-57 2} shown in when mixed by the mixer 53c FIG 3 (b) . Each IF filter 57 _{1-57 2} selects and outputs the IF signal (intermediate frequency signal fs ± fb) contained in the intermediate frequency band indicated by the dotted line in FIG. 3, the frequency converter 59 _{1-59 2} IF filter 57 _1-57 signal input from _2, mixing the local oscillation signal of frequency fs to be output from the filter 58, and outputs the demodulated baseband signal shown in Figure 3 (c).

AD converter 60 _through 603 ₂ converts the baseband signal demodulated by the frequency converter 59 _{1-59 2} into digital data. The phase comparison circuit 61 calculates and outputs the phase difference φ of the reception signal arriving at each antenna, and the amplitude comparison circuit 62 calculates and outputs the amplitude difference A of the reception signal arriving at each antenna. The estimation circuit 63 estimates the signal arrival direction (the direction of the target) from the phase difference φ, the amplitude difference A, and the antenna interval.
As described above, according to the third embodiment, in the monopulse type radar device, it is only necessary to provide one front end 53 in common for each antenna, so that the configuration can be simplified and the compensation can be performed as in the related art. Means and adjustment circuits can be eliminated.

(C) Modification FIG. 16 shows a modification of the third embodiment. The second switch 54, the IF filters 57 _{1 to} 57 _{2 and the} frequency converters 59 _{1 to} 59 ₂ in the third embodiment (FIG. 15) are eliminated, and the front-end output is connected to the AD converters 60 _{1 to} 60 ₂ . . Further, a sampling control circuit 64 is provided, and when the reception signal of the i-th (i = 1, 2) antenna 51 _i is input to the front end 53, only the AD converter 60 _i corresponding to the i-th antenna is connected to the front end. Is controlled so as to sample the output of A and perform AD conversion.

With the configuration described above, the output of the AD converter 60 _through 603 ₂ is equal to that the AD conversion by sampling the output of the frequency converter 59 _{1-59 2} of the third embodiment. Therefore, the phase comparator circuit 61 the output of the AD converter 60 _through 603 _2, and supplies to the amplitude comparison circuit 62, a phase comparator circuit 61, the phase difference of the received signal arriving at each antenna by an amplitude comparison circuit 62 phi, amplitude If the difference A is obtained and output, the arrival direction estimation circuit 63 estimates and outputs the signal arrival direction (direction of the target) from the phase difference φ, the amplitude difference A, and the antenna interval.
According to this variant, the sampling control circuit 64 in comparison with the third embodiment is increased, the second can omit the switch 54 and the frequency converter 59 _{1-59 2,} it is possible to reduce the component.

FIG. 17 is a configuration diagram of a radar apparatus according to a fourth embodiment in which antennas are used for both transmission and reception, and the same parts as those in the first embodiment in FIG. In the first embodiment, the antennas 11 _{1 to} 11 _N are used exclusively for reception. In the fourth embodiment, the antennas 11 _{1 to} 11 _N are shared for transmission and reception.
In FIG. 17, reference numeral 71 denotes a transmitting circuit, and 72 denotes a third switch for connecting the antennas 11 _{1 to} 11 _N selected by the first switch 12 to the transmitting circuit 71 and the front end 13 alternately.
The first switch 12 cyclically selects the antennas 11 _{1 to} 11 _{N based} on the antenna selection signals S _{1 to SN as} shown by the dotted lines in FIG. The third switch 72 alternately connects the antenna selected by the first switch 12 to the transmission circuit 71 and the front end 13, and uses the antenna for both transmission and reception.

Thus, (1) the first antenna 11 ₁ by the transmission / reception → (2) the second antenna 11 transmit / receive according to ₂ → · · · (3) the N-th antenna 11 transmit / receive according to _N → (4) first It is possible to cyclically select the antennas 11 _{1 to} 11 _N , such as transmission / reception by the antenna 11 ₁ , and use each antenna alternately for transmission and reception. Therefore, according to the fourth embodiment, it is only necessary to provide one front end for each antenna, and the antennas can be shared for transmission and reception.

In the fourth embodiment, all antennas are used for both transmission and reception. However, there is a case where only some transmission and reception are shared and others are used for reception only. Figure 19 is transmitted and received shared only _one first antenna 11, a block diagram of a radar apparatus according to a fifth embodiment in which the receive-only other antenna 11 ₂ to 11 _N, the first embodiment and the same parts in FIG. 1 Have the same reference numerals.
In FIG. 19, 71 is a transmission circuit, and 73 is a third switch. The third switch 73 connects the transmitting circuit 71 alternately and for cyclically connecting the antennas 11 ₁ to 11 _N to the front end 13 in the first switch 12 to the first antenna 11 _1. That is, as shown in the time chart of FIG. 20, the antennas 11 ₁ to 11 _N are connected to a cyclically front end 13 by the first switch 12 on the basis of the antenna selection signal S ₁ to S _N of the switching frequency fs Used for reception (reception cycle). The antenna 11 ₁ both transmission and reception is used in the transmission is connected to the transmitting circuit 71 by the third switch 73 on the basis of the transmission circuit selection signal TR frequency N · fs (transmission cycle). The switch control unit 16 generates the antenna selection signals S _{1 to} S _N and the transmission circuit selection signal TR so that reception and transmission are performed alternately.

  As a result, (1) transmission by the first antenna / reception by the first antenna → (2) transmission by the first antenna / reception by the second antenna → ... (3) transmission by the first antenna / reception by the Nth antenna → (4) Transmission by the first antenna / Reception by the first antenna →..., Only the first antenna is shared for transmission and reception, and the other antenna can be used exclusively for reception. Also, it is only necessary to provide one front end commonly for each antenna. Although only one antenna is used for transmission and reception, two or more antennas can be used for transmission and reception.

FIG. 21 is a configuration diagram of a radar apparatus according to a sixth embodiment in which antennas are shared for transmission and reception, and the same reference numerals are given to the same parts as those in the first embodiment in FIG. In the first embodiment, the antennas 11 _{1 to} 11 _N are used exclusively for reception. In the fourth embodiment, the antennas 11 _{1 to} 11 _N are shared for transmission and reception.
In FIG. 21, reference numeral 71 denotes a transmission circuit, and 75 ₁ to 75 _N are third switches provided between the antennas 11 _{1 to} 11 _N and the first switch 12, and the antennas 11 _{1 to} 11 _N are connected to the first switch. Reference numeral 76 denotes a phase / amplitude adjustment circuit for selectively connecting the switch 12 and the transmission circuit side, and adjusting the phase or amplitude of a transmission signal input to each antenna. In the transmission cycle, the third switches 75 ₁ to 75 _N simultaneously connect the phase / amplitude adjustment circuit 76 to all the antennas 11 _{1 to} 11 _N and input a transmission signal having a predetermined phase or amplitude adjustment to each antenna. Then, radio waves are radiated in a desired antenna radiation pattern.

The switch control unit 16 generates the antenna selection signals S _{1 to} S _N and the transmission circuit selection signal TR as shown in the time chart of FIG. 22 so that reception and transmission are performed alternately. That is, the first switch 12 and the third switches 75 ₁ to 75 _N cooperate to input the transmission signal whose phase or amplitude has been adjusted to all the antennas 11 _{1 to} 11 _N (transmission cycle), and set the desired antenna radiation pattern. Each antenna is cyclically connected to the front end 13 (receiving cycle) while forming and radiating and alternately transmitting. As a result, (1) transmission by all antennas / reception by first antenna → (2) transmission by all antennas / reception by second antenna → ... (3) transmission by all antennas / reception by Nth antenna → (4 ) Transmission by all antennas / reception by first antenna →..., Transmission by all antennas and cyclic reception by each antenna are performed alternately.
As described above, according to the sixth embodiment, it is only necessary to provide one front end in common for each antenna, and each antenna can be used for both transmission and reception, and furthermore, a desired antenna radiation pattern can be formed at the time of transmission. Can be.

FIG. 23 is a configuration diagram of a monopulse radar apparatus according to a seventh embodiment in which antennas are shared for transmission and reception, and the same parts as those in the third embodiment in FIG. 15 are denoted by the same reference numerals. Although the third embodiment is the case of using the first, the second antenna 51 _{1-51 2} dedicated to receiving, in the seventh embodiment share the antennas 51 ₁ to 51 ₂ to transmit and receive.
23, 81 transmitting circuit, 82 denotes a third switch that alternately connects the antenna 11 ₁ to 11 ₂ which is selected by the first switch 52 to the transmitting circuit 81 and the front end 53.

The first switch 52 is connected to the third switch 82 selects an antenna 51 _{1-51 2} alternately from the antenna selection signal S ₁ to S _2. The third switch 82 alternately connects the antenna selected by the first switch to the transmission circuit 81 and the front end 53, and uses the antenna for both transmission and reception.
Thus, (1) a first transmission / reception by the antenna 51 ₁ → (2) transmission / reception → (3) the first transmission / reception by the antenna 51 ₁ by ₂ second antenna 51 → (4) the second antenna 51 ₂ selects an antenna 51 _{1-51 2} alternately and so transmit / receive → · · · according to, and use each antenna to transmit and receive alternately. Therefore, according to the seventh embodiment, it is only necessary to provide one front end for each antenna, and the antennas can be shared for transmission and reception.
As described above, the present invention has been described with reference to the embodiments. However, the present invention can be variously modified in accordance with the gist of the present invention described in the claims, and the present invention does not exclude these.

FIG. 1 is a configuration diagram of a radar device according to a first embodiment. It is a time chart of antenna switching. FIG. 4 is a spectrum diagram for explaining the operation of each unit. FIG. 5 is a configuration diagram (first modification) of the amplitude control according to the first embodiment. FIG. 4 is an explanatory diagram of amplitude weighting of a corresponding antenna. FIG. 4 is an explanatory diagram of a switch-on time of amplitude control. FIG. 9 is a configuration diagram of a radar device according to a second modification of the present invention. It is a lineblock diagram of a radar device of the 3rd modification of the present invention. FIG. 14 is a configuration diagram of a radar device according to a fourth modification of the present invention. FIG. 9 is a configuration diagram of a radar device according to a second embodiment. 5 is a time chart of an antenna selection signal and a sampling signal of an AD converter. FIG. 14 is a configuration diagram of a radar device that is a first modification of the second embodiment. FIG. 14 is a configuration diagram of a radar device that is a second modification of the second embodiment. 13 is a time chart for explaining the operation of the second modification. FIG. 13 is a configuration diagram of a monopulse type radar device according to a third embodiment. FIG. 14 is a configuration diagram of a radar device that is a modification of the third embodiment. FIG. 13 is a configuration diagram of a radar apparatus according to a fourth embodiment when all antennas are used for transmission and reception. It is a time chart of antenna selection and transmission / reception switching of the fourth embodiment. It is a block diagram of the radar apparatus of 5th Example at the time of transmitting and receiving and sharing one antenna. It is a time chart of antenna selection and transmission / reception switching of the fifth embodiment. FIG. 16 is a configuration diagram of a radar apparatus according to a sixth embodiment when all antennas are used for transmission and reception. It is a time chart of antenna selection and transmission / reception switching of the sixth embodiment. FIG. 14 is a configuration diagram of a monopulse type radar device according to a seventh embodiment. FIG. 2 is a configuration diagram of a receiving unit of a radar device having an active array antenna. FIG. 2 is a configuration diagram of a receiving device of a DBFN (beam scan) radar device. FIG. 2 is a configuration diagram of a receiving device of a DBFN (multi-beam) radar device. FIG. 2 is a configuration diagram of a receiving device of the monopulse radar device.

Explanation of reference numerals

111 to 11N a plurality of antennas 12 first switch 13 front end 13a RF amplifier 13b local oscillator 13c mixer (frequency converter)
14. Second switch 15 Oscillator 16 Switch controllers 171 to 17N IF filter 18 Low-pass filters 191 to 19N Mixer (frequency converter)
.. 20N to 20N AD converters 211 to 21N phase shifters 221 to 22N amplitude adjustment unit 23 phase control circuit 24 amplitude control circuit 25 adder

Claims (4)

In a radar device having an array antenna configuration including a plurality of antennas, an adjustment circuit provided for each antenna and adjusting a phase or an amplitude of an input signal, and a synthesis circuit for synthesizing the phase or amplitude adjusted signals,
A front end that is provided in common for each antenna and amplifies each antenna reception signal sequentially input and frequency-converts it to an intermediate frequency signal
A switch that cyclically connects each antenna to the front end at a given switching frequency,
An intermediate frequency filter that passes only the intermediate frequency signal output from the front end,
An AD converter provided for each antenna and AD-converting the intermediate frequency filter output;
When a reception signal of the i-th antenna is input to the front end, a sampling control circuit that performs an AD converter corresponding to the i-th antenna to sample an intermediate frequency filter output to perform AD conversion;
A radar device which detects a target from a desired direction by performing phase adjustment or amplitude adjustment on output signals of respective AD converters and combining them. 2. The radar apparatus according to claim 1, further comprising a delay circuit provided at a preceding stage of the AD converter to make AD conversion timing coincide. In a radar device having an array antenna configuration including a plurality of antennas, an adjustment circuit provided for each antenna and adjusting a phase or an amplitude of an input signal, and a synthesis circuit for synthesizing the phase or amplitude adjusted signals,
A front end that is provided in common for each antenna and amplifies each antenna reception signal sequentially input and frequency-converts the signal into an intermediate frequency signal;
A switch that cyclically connects each antenna to the front end at a given switching frequency,
An AD converter for AD-converting the intermediate frequency signal output from the front end;
An A / D converter performs an A / D conversion on the intermediate frequency filter output at a frequency obtained by multiplying the switching frequency by the number of the plurality of antennas, and outputs an A / D conversion output when the reception signal of the i-th antenna is input to the front end. means for storing as a signal corresponding to the i antenna,
A radar device which detects a target from a desired direction by performing phase adjustment or amplitude adjustment on output signals of an AD converter corresponding to each antenna and combining them. In a monopulse radar device including two antennas, a comparing unit that compares the phases and / or amplitudes of the reflected signals arriving at the two antennas, and a direction-of-arrival estimating unit that estimates the direction of arrival of the reflected signal based on the comparison result,
A front end that is provided in common for each antenna and amplifies each antenna reception signal sequentially input and frequency-converts the signal into an intermediate frequency signal;
A switch that alternately connects each antenna to the front end at a given switching frequency,
An AD converter that is provided corresponding to each antenna and AD converts an intermediate frequency signal output from the front end;
When a reception signal of the i-th antenna is input to the front end, a sampling control circuit for performing sampling and AD conversion by an AD converter corresponding to the i-th antenna,
A monopulse type radar apparatus, wherein the output signal of each AD converter is used as the reflection signal and the phase or amplitude is compared to estimate the arrival direction of the reflection signal.

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