JPH0664140B2 - Direction identification radar device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention correlates a detection signal of a reflected wave from a target by a radio wave modulated by a pseudo-random code to determine the responsiveness of the existence quadrant determination of the target. The present invention relates to a direction identifying radar device that improves radiance and performs quadrant determination.

In the present invention, the direction identification means the determination of the quadrant in which the target object exists.

[Problems to be Solved by Prior Art and Invention]

As a conventional active target detection device, a target detection radar device that performs correlation processing of reflected signals from a target in all directions with the same transmitting and receiving antennas using a single pseudo-random code signal and detects only when the target approaches Are known.
This is to detect that the distance to the target has become equal to or less than a predetermined value, and the direction of the target in that case cannot be detected.

Further, as a device for detecting a target direction, two transmitting and receiving antennas are provided, and two or more pseudo-random code signal projection quadrants and a receiving quadrant in which the receiving antennas are switched at high speed by the transmitting antennas are provided. A prior art has been proposed in which detection quadrant patterns are combined, correlation processing is performed, and a weak reflection signal of a target in the detection quadrant is detected to obtain target approach and target direction information.

This prior art will be described with reference to FIG. This prior art is shown in Japanese Patent Application No. 62-269420 of the present applicant.

FIG. 6 is constructed as follows. The antenna section is composed of a pair of transmitting antennas 11 and 12 and receiving antennas 13 and 14. The oscillating wave from the radio frequency oscillator 15 is sent to the pair of modulators 17 and 18 via the distributor 16, and the output modulated by the external input is sent to the transmitting antennas 11 and 12.

Received inputs from the pair of receiving antennas 13 and 14 are sent to the microwave switching circuit 210 together with the clock of the clock generator 200 to perform switching, and the switching output is sent to the demodulator together with the output of the radio frequency oscillator 15. The demodulated output of the demodulator 21 is sent to the power distributor 22 and divided into four.

The oscillation output of the voltage controlled oscillator 25 is sent to the first and second pseudo-random code generators 24A and 24B, the first outputs are sent to the modulators 17 and 18, and the second outputs are correlators. 31,
The third output is sent to 34, and the third output is sent to correlators 32 and 33, respectively.
The outputs of the correlators 31 to 34 are transmitted to the determiner 45 via the low pass filters 311 to 341.

The judging device 45 includes two comparators 431, 432 and two switches 451, 4
Including 52 and. The outputs of the correlators 31 and 32 are respectively filters 31
Input to comparator 431 via 1,321 and switch compared
451 and the outputs of correlators 33 and 34 are filtered by filter 3 respectively.
It is input to the comparator 432 via 31,341 and compared and output to the switch 452. The output from the clock generator 200 is input to the first and second switches 451 and 452, and the comparator 4
The outputs of 31,432 are input to the switch, and outputs X ₁ and X ₂ are obtained from the first switch 451 and outputs X ₃ and X ₄ are obtained from the second switch 452.

In FIG. 6, the radio frequency (RF) output from the RF oscillator 15 in the device is divided into two by the distributor 16 and distributed, and then the modulator 17 generates pseudo-random code generated by the first pseudo-random code generator 24A. Transmit antenna after being modulated by code
Radiated above 11 above. The modulator 18 modulates the pseudo random code generated by the second pseudo random code generator 24B, and then radiates downward from the transmitting antenna 12.

The radiated radio wave is reflected by the target object, is received by the left reception antenna 13 or the right reception antenna 14, and the reception radio wave is alternately switched by the microwave switching circuit 210 and then output from the oscillator 15 by the demodulator 21. It is homodyne detected and demodulated using the frequency output.

The homodyne-detected signal is divided into four in the power divider 22, and first, the same as the reference when delayed by the reflection time τ from the reference pseudo-random code (the left end output of 24A) used for the radio frequency modulation in the correlator 31. And the code that is delayed by 1 bit (the second output on the left of 24A) is correlated.

The correlator 32 also correlates with the 1-bit lead code (the third left output of 24A). Similarly, the correlator 33 correlates with the 1-bit delay code generated by the pseudo random code generator 24B, and the correlator 34 correlates with the 1-bit advance code.

The outputs from the four correlators 31, 32, 33, 34 are respectively integrated via the low-pass filters 311, 321, 331, 341, and the decision unit 45 decides the direction of the target object.

Next, the operation of the correlator will be described. For example, the correlator 31 multiplies the two inputs via the balanced modulator. The two inputs are pseudo-random signals input from the lower side, and the inputs from the left side are electron distributor output signals. Moreover, the correlator output is an output that detects an analog signal of the Doppler frequency if there is a correlation, and is a 0 signal (no signal) if there is no correlation.

Next, a method of detecting the existing area of the target object will be described.

Four antennas are installed at 90 ° intervals, and diagonally positioned antennas are used as a pair, and one of the two pairs is used as a transmitting antenna and the other is used as a receiving antenna. Of these, the transmission pattern is always transmitted. In order to distinguish whether there is a reflection in the upper or lower pattern, the pseudo random code is made different for the upper and lower (or left and right) patterns.

On the other hand, in the reception pattern, the reception antennas 13 and 14 are connected to the microwave switch 210 in order to distinguish whether the reception pattern is received from the left or right (or the top and bottom), like the transmission pattern.
Identification is performed by switching by.

The correlators 31, 32, 33, 34 correlate with the same code as each of the two types of pseudo random codes used for modulation of the transmission signal, and with a code delayed by 1 bit and a code advanced by 1 bit. At this time, based on the correlation signal from the correlator, the determination unit 45
Then, multiplication and integration calculation of two sets of signals are performed to obtain signals corresponding to four kinds of combined patterns. For example, when the target is approaching from the lower left and the round trip time of the radio wave between the radar device and the target is within 1-bit correspondence time, the pseudo random code used to modulate the radio wave emitted from the lower transmission antenna 12. And a code 1 bit behind this code (made by the pseudo-random code generator 24B, the correlator 33
The output of the correlator 33 is compared with the outputs of other correlators while the microwave switch circuit 210 is connecting the left receiving antenna 13 and the demodulator 21. To a high level. Therefore, during this period, the judging device 45
The target detection signal is output from the comparator 432 in the switch 4
Sent to 52. This switch 452 is a clock generator 200.
Comparing the timing pulse signal created by
Output of 432 is output X ₃ or another output X ₄
The target detection signal appears on the output side of the comparator 432 only while the microwave switch circuit 210 is connected to the left receiving antenna 13, although the switching is performed in synchronization with the reception switching of the left and right receiving antennas 13 and 14. The target detection signal is output to the output terminal X ₃ of the determiner 45. Similarly, if the target approaches from the upper left, X ₂ , and if the target approaches from the upper right, X ₁ , X _4.
A target detection signal is output from the device, and the existence area of the target object can be confirmed.

However, the prior art shown in FIG. 6 performs detection determination in the target quadrant direction, and there is a problem in that the response of target detection is poor due to intermittent detection signals due to switching of the receiving antenna. It should be noted that in this prior art, there is a time interruption due to the switching of the received signal, which makes continuous operation difficult, and a spike waveform occurs due to the switching in the received signal processing, causing an unstable period of the detection signal. However, there is also a problem in that, for example, when switching is performed using a 400 Hz power supply, the received signal is interrupted for 2.5 _msec .

The main object of the present invention is to use beam detection signals in four directions,
To improve the responsiveness of target detection by instantly detecting the target without using a switching mechanism, comparing the beam detection signal levels, and performing quadrant determination by continuous response with no interruption time of the target quadrant detection. is there.

[Means for Solving the Problems]

According to the present invention, each has two transmitting antennas and two receiving antennas, and an antenna unit that obtains a composite pattern in the target detection quadrant range by each projection pattern, and transmits and receives RF radio waves modulated by a plurality of types of pseudo random codes. Along with
Transmitter / receiver unit that continuously outputs the correlation detection between the transmitted pseudo-random code signal and the received pseudo-random code signal for each receiving antenna separately, compares the correlated signal and uncorrelated signal of each beam, and instantly detects the target object. The adjacent signal level of each beam is compared by using the detected signal and the synthesized pattern output signal by the DC voltage of the correlation output of the transceiver unit, the quadrant signal of the target existence is detected, and the target object in all directions is interrupted. And a quadrant determining unit that determines the quadrant in which the target exists without fail.

The configuration of the present invention has the following effects. In each of the transmitting / receiving antenna section and the transmitting / receiving section, a projection pattern of two transmitting antennas and two receiving antennas is used to form a composite pattern in the four-quadrant direction. In addition, two pseudo random codes A and B are individually modulated from the upper and lower sides of the transmitting antenna, and RF radio waves are emitted.

Without switching the reception output of the left and right receiving antennas in time division,
Homodyne detection is performed on the left and right lines continuously in terms of time.

For the local signals to the left and right homodyne detection demodulators, a splitter (25 to 30 dB or more) with good isolation is used to improve the separation of the left and right received signals.

The received signals on the left and right are distributed to respective powers, correlation is performed by the two pseudo random codes A and B, and beam signals in four directions are continuously output as a DC voltage.

In the quadrant determination unit, one of the beam output signals in the four directions is compared using left and right uncorrelated signals, and it is instantly detected that there is a target reflection signal, and a latch signal is transmitted by a trigger pulse.

The beam output signals in the other four directions compare the reception levels of adjacent quadrant pairs of the respective beams to accurately determine the target quadrant range and output them as binary signals.

The target existence quadrant is determined by the latch signal that instantaneously detects the target and the binary signal that compares the signal levels of the respective beams, and the target quadrant signal is output.

〔Example〕

FIG. 1 shows a radar apparatus having a quadrant identification function as an embodiment of the present invention.

The transmission / reception antenna unit 10 includes a pair of transmission antennas T (upper) 11,
T (bottom) 12 and a pair of receiving antennas R (left) 13 and R (right)
It is composed of 14 and.

The oscillation wave of the RF oscillator 15 of the transceiver unit 100 is transmitted to the pair of modulators 17 and 18 via the distributor 16, and is modulated by the pseudo random code A and B signals from the pseudo random code generator 24, respectively. , The modulated waves are transmitted antenna T (upper) 1
It is emitted from 1, T (bottom) 12. On the other hand, the reception inputs captured by the pair of reception antennas R (left) 13 and R (right) 14 are transmitted to the demodulator I20 and the demodulator II21, respectively. Each demodulation input is homodyne detected by the output from the RF oscillator 15 divided into two by the distributor 19, demodulated, and sent to each of the power distributor I22 and power distributor II23.

The distributor 19 is an isolation between the demodulators I and II, for example, 25
In order to obtain ~ 30dB or more, the left and right receiving antennas are separated using a hybrid distributor.

The received signal divided into three by the power distributor I22 is received by the receiving antenna R in the transmitting / receiving antenna pattern shown in FIG.
(Right) The output of 14 is the transmit antenna pattern T (top), T
This is a combined reception pattern of (bottom) and reception antenna pattern R (right), and includes the signals of beam 1 and beam 4.
In the correlators 31, 32 and 33, the reference pseudo-random codes A and B used for modulation of the RF oscillation signal and the code which is the same as one of the references and is delayed by 1 bit are correlated by the conventionally known correlation method. It is then output through the reduction filter LPF.

Therefore, the correlator 31 inputs the output signal of the beam 4 to the quadrant determination unit 400 via the low pass filter 311 using the correlation signal of the pseudo random code A. Similarly, the correlator 32 inputs the correlation signal of the pseudo-random code B as the output signal of the beam 1 to the quadrant determination unit 400 via the low pass filter LPF321. The received signal divided into three by the power distributor II23 is the output of the transmitting / receiving antenna R (left) 13 shown in FIG. 2 and the transmitting antenna patterns T (upper) and T (lower) and the receiving antenna pattern R (left). ) And the signals of the beam 2 and the beam 3 are included in the combined reception pattern and correlated in the same manner as above using the correlators 34, 35 and 36, and the correlator 34 compares the output signal of the beam 3 with the correlator 35. Are input to the quadrant decision unit 400 via the low-pass filters as output signals of beam 2.

The output signal of each beam is a detection signal in each quadrant direction, but the quadrant determination unit 400 performs predetermined setting and accurate quadrant determination, and outputs the quadrant detection signals as output terminals X _{1 to} X _4.
Output to.

The transmission signals modulated by the pseudo random codes A and B are radiated from the upper and lower transmission antennas, and the reception signals reflected from the target object are received by the left and right reception antennas. The received signal is correlated by the correlator 31, 32, 34, 35 by the pseudo random code A delayed by 1 bit in the pseudo random code generator 24 at a time corresponding to the round-trip propagation distance to the target object. Be taken.

When the pseudo random codes A and B are in phase with each other in the correlator, an extremely high correlation output signal is generated as a signal. Correlators 33 and 36 take correlation by a pseudo-random code with a 1-bit phase advance, so extremely low-level correlation output for other pseudo-random codes or codes that are out of phase by 1 bit or more. Only happens. This is called a decorrelation signal. For this principle,
For example, the document “SPREAD SPECTRUM SYSTEMS, RC
DIXON, "The present invention utilizes this principle.

When a code (pseudo-random code) is divided into two, and the other is subjected to correlation processing through the delay circuit, the correlation output is obtained if the phase difference (time difference) is ± 1 bit. It is a signal for which no correlation output is obtained with any other phase difference (time difference). In other words, whether or not the target object exists within the set distance is determined by the correlation process between the code propagating between the transmitting antenna, the target, and the receiving antenna, and the code forcibly delayed in the transceiver. Since the target radio wave reflection coefficient varies, it cannot be specified using the threshold as an absolute value. Therefore, if the uncorrelated signal is used for the threshold, it is possible to make a relative judgment even with respect to the strength of the received power. As the code (pseudo random code) used here, a code represented by the M series is well known.

Therefore, the uncorrelated signal is a non-correlated signal that does not correlate with noise inside the device or an interfering signal from the outside, that is, a non-correlated signal, and the uncorrelated signal depends on the electrical noise environment inside and outside the device. As a signal with an adaptive threshold level, it was compared with each of the correlation signals of beam 4 and beam 1 in the signal detector No. 1, and the correlation signal approached within the propagation distance of 1 bit of the code in the round trip distance to the target. If the target is located within the set range and the target reflects radio waves, a detection signal is output and sent to the trigger pulse generator 42.

Among them, the correlation output signal is compared with the beam signal of the DC voltage by the comparator of the signal comparator, is sent to the quadrant determiner, is held by the latch signal from the trigger pulse generator, and the state of the output signal in the target presence direction is set to 2 Output from the quadrant determiner by a value signal.

Details of the operation of the quadrant determination unit 400 will be described.

In signal detector No. 1 40, beam 4 and beam 1
Each of the correlation signals of 1 and the non-correlation signal from the correlator 33 are compared, and the correlation signal is a correlation signal when the round trip distance to the target approaches within the propagation distance of 1 bit of the code, and the target is within the setting range. If it is located and its target reflects radio waves, a detection signal is output and sent to the trigger pulse generator 42. Similarly, beam detector 3 is used for signal detectors No. 2 and 41.
And the detection signal of beam 2 is sent to the trigger pulse generator. When the detection signal at the moment when the target is detected by any of the beams 1 to 4 is input to the trigger pulse generator 42, a trigger pulse is generated, a latch signal is sent to the quadrant determiner 44, and a signal for each correlation is generated. The output signal from the comparator 43 is held.

The correlation output signals of the beams 1 to 4 are input to the signal comparator 43 as a DC voltage. The output signals of the beams 1 to 4 are DC voltage signals 1 to 4 in the direction of the target object as shown in the combined reception pattern of FIG. 2C, and the adjacent quadrants I, II of the beams 1 to 4 are A comparison is made of the signal voltage levels of the pair III and IV, for example, the DC voltage levels of the beam 4 signal and the beam 1 signal of the correlation output of the beams 4 and 1 of the quadrants IV and I.

The signal comparator 43 is calibrated by a commonly used comparator circuit, and as shown in FIG. 3, for example, the signal levels of the beam 4 signal and the beam 1 signal are compared by a DC voltage, and the DC voltage of the beam 4 signal is If higher, comparator circuit II43
As for the output of 2, the output signal of 0 of the binary signal is sent to the quadrant determiner 44 as the output signal of 1 if the beam 1 signal is high. Similarly, the beam 2 signal and the beam 3 signal are in the comparator circuit I431, the beam 4 signal and the beam 3 signal are in the comparator circuit III433, and the beam 1 signal and the beam 2 signal are
The comparator circuit IV434 compares the voltages and outputs the binary signal to the quadrant determiner 44. Test results show that the comparison accuracy at this DC voltage level is detected within a level difference of about 0.5 dB.

The quadrant determiner 44 uses the binary signals from the comparator circuits I to IV 431 to 434 by the instantaneous latch signal from the trigger pulse generator 42 when the target is detected, and outputs the comparator output signals I to IV as shown in the example of FIG. The binary signal is held, and the existence quadrant of the target object is determined according to the manner of holding the signal. The relationship between the output signal state of the comparator circuit and the existence quadrant of the target object with respect to the existence quadrant of the target object is as shown in FIG. For example, if a target object is present in quadrant IV, the output signals of comparator circuits II and III are binary signals of 0, and comparator circuits I and IV are binary signals of 1.

〔The invention's effect〕

According to the present invention, a beam detection signal in four directions is used to instantly detect a target without using a switching mechanism,
By comparing the beam detection signal levels with each other, quadrant determination is performed by continuous response with no interruption time of target quadrant detection, and the responsiveness of target detection can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a direction identification radar device as an embodiment of the present invention, and FIG. 2 is a transmission antenna pattern, a reception antenna pattern, and a synthetic reception pattern synthesized by the transmission / reception antennas of FIG. And FIG. 3 is a diagram showing the direction of the target object, FIG. 3 is a diagram showing a signal comparator in the device of FIG. 1, FIG. 4 is a signal waveform diagram for explaining the operation of the device of FIG. 3, and FIG. FIG. 6 is a diagram showing the relationship between the comparator output and the existing quadrant, and FIG. 6 is a diagram showing a conventional type device. 10 ... Transmission / reception antenna section, 11,12 ... Transmission antenna, 13,14 ... Reception antenna, 15 ... RF oscillator, 16 ... Distributor, 17,18 ... Modulator, 19 ... Distributor, 20,21 ... Demodulator, 22 , 23 ... Power distributor, 24 ... Pseudo random code generator, 25 ... Voltage controlled oscillator, 31, 32, 33, 34, 35, 36 ... Correlator, 311-361 ... Low pass filter, 40, 41 ... Signal detection 42 ... Trigger / pulse generator, 43 ... Signal comparator, 44 ... Quadrant judging unit, 100 ... Transceiver unit, 400 ... Quadrant judging unit.

Claims (2)

[Claims] 1. An antenna section (10) for obtaining transmission / reception combined patterns by alternately arranging two transmitting antennas and two receiving antennas at 90 ° intervals alternately for transmitting and receiving, and outputs the outputs of an RF oscillator (15) first. 1 is inputted to the first and second modulators via the distributor (16), modulated by the first and second pseudo random codes from the pseudo random code generator (24) and sent to the transmitting antenna. , The second modulator (17,1
8) and the output of the RF oscillator to the demodulator via the second distributor (19) to demodulate the received signals from the two receiving antennas, the first and second demodulators (20, 21). ) And the first
The output of the second demodulator is distributed and the output of the second demodulator is distributed to the first power distributor (22) which is sent to the first, second and third correlators (31, 32, 33). Then, the second power distributor (23) to be sent to the fourth, fifth and sixth correlators (34, 35, 36) and the output of the first power distributor are transferred to the pseudo random code generator ( 24) from which the first and second pseudo-random codes are correlated and the beam signal 4 is respectively passed through the low-pass filter, and
The first and second correlators that output the beam signal 1 and the output of the first power distributor are correlated by a third pseudo random code that is one bit ahead of the first or second pseudo random code. A third correlator that outputs a first decorrelation signal through a low-pass filter and outputs of the second power distributor from the pseudo random code generator (24) The fourth and fifth correlators that correlate with the pseudo random code of the above and output as beam signal 3 and beam signal 2 through the respective low-pass filters and the output of the second power distributor are the above-mentioned A transmitter / receiver unit including a sixth correlator that correlates with a third pseudo-random code that is one bit ahead of the first or second pseudo-random code and outputs the result as a second decorrelation signal through a low-pass filter ( Ten
0), a first signal detector (40) for detecting the presence of a target in a quadrant by comparing the beam signal 4, the beam signal 1, and the first decorrelation signal, and the beam signal. 2, a beam signal 3, and a second signal detector (41) for detecting the presence of a target in a quadrant by comparison with the second decorrelation signal, and the first and second signal detection. A trigger pulse generator (42) that sends out a latch signal by a trigger pulse from the output of the detector is compared with each of the above two beam signals corresponding to the adjacent quadrant directions, and the target quadrant range is judged to be a binary value. Signal comparator to output as a signal (4
3) and a quadrant determiner (44) that holds the binary signal by a latch signal from the trigger pulse generator, determines a target existing quadrant according to the signal holding state, and outputs a target quadrant signal. A direction identification radar device comprising: a quadrant determination section (400). 2. The direction identifying radar apparatus according to claim 1, wherein homodyne detection is continuously performed by two demodulators on the right and left sides without switching the reception outputs of the left and right receiving antennas in a time division manner.