JPS61194377A - Phase matching circuit - Google Patents

Abstract

PURPOSE:To automatically perform phase matching between receiving systems and to make it possible to always detect an accurate azimuth angle and an accurate angle of elevation, by sending a reference signal to first, second and third receiving systems from a reference signal generation circuit and detecting the phase differences between the receiving systems. CONSTITUTION:A matching timing signal D1 is inputted to a reference signal generation circuit 24 and sample hold circuits 20, 21 from the outside during a time out of the data effective region within the pulse repeating period of radar. The reference signal generation circuit 24 generates a reference signal E1 in synchronous relation to said timing signal D1 to output the same to couplers 15, 16, 17. This reference signal E1 is supplied to phase detectors 13, 14 through first, second and third receiving systems. The outputs of the phase detectors 13, 14 are changed by the amplitude and phase difference of a binary signal and outputted as a fixed error if phase non-matching is present in the first, second and third receiving systems. Phase adjustment is performed on the basis of said error output by phase shifters 18, 19.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in monopulse radar, etc., and is composed of three receiving systems for detecting azimuth angles and elevation angles. The present invention relates to a phase matching circuit that corrects inherent phase differences, and particularly to a phase matching circuit that is improved to automatically correct phase differences between each received sequence.

As is well known, the angle detection circuits used in monopulse radar etc.
) is the sum signal Σ(L
O+RO) and the subtracted difference signal ΔAL(LO-RO
), ΔEL (Do-L(Th))
Input each to the receiving system of the series, and use the sum signal as a reference.
The azimuth angle and elevation angle of the target object are detected by detecting the phase difference between the two difference signals.

In this angle detection circuit, if there is a unique phase difference between the three receiving systems, the phase difference between the received signals will be detected as different values, making it impossible to obtain accurate azimuth and elevation angle.

Therefore, in order to eliminate the phase difference between the receiving systems, after setting the phase shift to O for each of the receiving circuits that make up the receiving system so that the unique phase difference of each receiving system becomes 0, the total phase shift of the receiving system is The phase of the receiving circuit is corrected and adjusted so that 0. Furthermore, the same phase adjustment as described above is also performed for phase shifts in the receiving system that occur due to aging or environmental changes.

This phase adjustment work requires a lot of man-hours, so
A phase matching circuit that can automatically perform phase matching became necessary.

[Conventional technology]

FIG. 3 is a block diagram of an angle detection circuit for explaining conventional phase matching, and FIG. 4 is an antenna pattern diagram and an antenna arrangement diagram for explaining the operation of a monopulse radar antenna.

In Figure 4, AI with the same beam characteristics.

The four antennas A2, Bl, and B2 are placed to the left of the antenna setting angle so that they overlap at the 172 output level at the maximum point of the antenna beam in the antenna setting direction θO.

They are placed above and below the symmetrical position on the right. Now, for example,
When the target object 27 is received by four antennas, the reception levels become <UL, OR, LL, and LR as shown in the figure.

The sum of the received signals Σ(LO+RO), the azimuth difference ΔAZ
(LO-RO), elevation angle difference ΔEL (00-LOo
) are input to each of the three receiving systems shown in FIG. (However, LO = UL + L
L, RO= UR+ LR, UO-UR+ UL,
LOo=L, R+LL. ) Each receiving system has the first. Second. The input signal frequency of 9G blood is lowered to 330MHz by the third mixer circuit 1°2.3, and the input signal frequency of 9G is lowered to 330MHz. Second
．． Third intermediate frequency amplification circuit (hereinafter referred to as IF circuit)>4.
5.6 and further 1 in the second mixer 7.8.9.
Stepping down to 0MHz, the second IF circuit 10, 11.12
Amplify the signal to a predetermined level and output it to the phase detector 13.
Output to 14.

The phase detectors 13 and 14 detect the 10 MHz band Σ signal, ΔAZ signal, and Σ signal output from each receiving system.
The level difference and phase difference between the signal and the ΔEL signal are detected, and if the phase difference between the ΔAZ signal and the ΔEL signal is delayed with respect to the Σ signal, a positive potential signal with a voltage corresponding to the level difference is sent to the opposite side. If the phase difference advances, a negative potential signal with a voltage corresponding to the level difference is output, and the azimuth and elevation angle of the target object are detected.

[Problem that the invention seeks to solve]

In the above angle detection circuit, if there is a phase shift inherent in the mixer circuit or IF circuit that constitutes each receiving system, the phase value of the input received signal will change, and accurate azimuth and elevation angles will be detected. can't get it.

Therefore, conventionally, after adjusting each receiving circuit that makes up the receiving system so that the phase shift is 0, the phase of the receiving circuit is corrected and adjusted again so that the total phase shift of the receiving system is O, and the phase difference between the receiving systems is adjusted. I had eliminated the gap. Furthermore, the same phase adjustment as described above is also performed for phase shifts in the receiving system that occur due to aging or environmental changes. There is a problem in that this phase adjustment work requires a large number of man-hours.

[Means for solving problems]

The present invention solves the above-mentioned problems and provides a phase matching circuit that automatically eliminates the phase difference between each receiving sequence. A phase matching circuit between the standard reception system and the other reception system of the angle detection circuit that detects a phase difference with an output signal using a phase detector, and generates a reference signal and outputs it to the input end of each reception system. A reference signal generation circuit is provided in the signal path of the other reception system, and the position of the other reception system is determined in response to the phase difference signal of the reference signal output from the phase detector of the angle detection circuit. This is accomplished by a phase matching circuit composed of a phase shifter that corrects the phase difference.

[Effect]

The above-mentioned phase matching circuit uses the outside of the effective time for angle detection within the pulse repetition time of the radar to generate the reference signal from the reference signal generation circuit in the first. Second. input to the third receiving system at the same time, and the second receiving system is input to the third receiving system as a reference. Each phase difference between the third receiving systems is detected by a phase detector connected between each system.

The phase difference signal detected by the phase detector is sampled by a sample hold circuit and held at a sample signal voltage.

The hold signal output from the sample hold circuit is A
After being converted into a digital signal by a /D converter, the signal is input to phase shifters provided at the inputs of the second and third receiving systems.

Phase shifters provided at the input ends of the second and third receiving systems correct the phases of the second and third receiving systems so that the phase difference between the receiving systems becomes O in accordance with the hold voltage.

In addition, a synthesizer is provided to perform phase difference correction every time a phase difference is detected by the phase detector, and the synthesizer synthesizes the second and subsequent detected phase difference signals of the phase detector and the hold signal of the sample and hold circuit. The phase shifter is phase-corrected using the composite signal to further reduce the phase difference.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Fig. 1 is a block diagram of a phase matching circuit according to an embodiment of the present invention, and Fig. 2 is a time chart for explaining the operation of the phase matching circuit. Ta.

As shown in the block diagram of FIG. 1, the phase matching circuit of one embodiment includes a first . Second. A coupler 15, 16, 17 connected to the input end of each third receiving system, and a phase shifter 18 and 19, and a second receiving system based on the first receiving system output from the phase detectors 13 and 14.
and sampling the phase difference signal between the third receiving system,
Sample and hold circuits 20 and 21 that hold sample signal voltages, synthesizers 25 and 26 that combine the phase difference voltage between the receiving systems and the hold voltage of sample and hold circuits 20 and 21, and sample and hold circuit 20.
and converting the hold voltage of 21 into a digital signal,
A/D converters 22 and 23 output to phase shifters 18 and 19, generate a reference signal in synchronization with a matching timing signal input from the outside, and connect the coupler 15.1 to the coupler 15.1.
6.17.

The operation will be explained with reference to the time chart of FIG. As shown in FIG. 2C, at a time CI outside the valid data area within the pulse repetition period of the radar, a matching timing signal D1 shown at D is externally applied to the reference generation circuit 24. It is input to sample and hold circuits 20 and 21. The reference signal generation circuit 24 generates a reference signal E in the same frequency band as the radar received wave shown in FIG. 2E in synchronization with the input matching timing signal D1.
1 and outputs it to the combiner 15.16.17.

The reference signal E1 inputted to the coupler 15, 16, 17 is connected to the first, second, and second nodes. The phase detector 13 passes through each third receiving system.
and output to 14. As is well known, the output of a phase detector changes depending on the amplitude and phase difference of two input signals, so the output of the phase detector varies depending on the amplitude and phase difference between the two input signals. If there is a phase mismatch in the system, it will appear as a fixed error.

The signal F1 shown in FIG. 2F represents the phase detection output of the phase detector 13 caused by phase mismatch between the first receiving system and the second receiving system,
When the second mismatch pulse F1 is detected, this signal is sampled and held by the sample and hold circuit 20, becomes a phase correction signal G, is input to the A/D converter 22, is converted into a digital signal, and is then sent to the phase shifter 18. Output. The phase shifter 1 corrects the phase of the reference signal in accordance with the input phase difference value.

Moreover, the phase correction signal G is applied at the time of the second matching.
The signal is held by the sample and hold circuit 20 until 20, and is combined with the second mismatched pulse F2 (see FIG. 2F) by the first combiner 25. This composite signal is input to the phase shifter 1, so that the phase difference is further reduced. Note that in the second time, since the phase correction has already been made in the first time, the mismatch pulse F2 at the time of the phase matching check is very small.

The phase matching between the first and second receiving systems has been described above, but the same operation is performed for phase matching between the first and third receiving systems.

In this way, phase matching between each receiving system can be automatically achieved,
The phase difference can be matched to approximately 1 of the phase matching loop gain bone.

However, if phase matching cannot be achieved from the receiving system input to the phase detector, it cannot be said that phase matching has been achieved in the receiving system route, so in the first receiving system, from the input to the first mixer, the second... In the third receiving system, the physical length from the input to the coupler is the same, and the coupler 15.1
Of course, the phase of the reference signal input to 6.17 must be matched.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to automatically match the phase between each of the three receiving systems of a monopulse radar, correct phase deviations that occur due to aging or environmental changes, and always maintain accurate phase matching. Azimuth and elevation angles can be detected.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a phase matching circuit according to an embodiment of the present invention, Fig. 2 is a time chart for explaining the operation of the phase matching circuit, and Fig. 3 is an angle detection circuit for explaining conventional phase matching. FIG. 4 is a pattern diagram for explaining the operation of the monopulse radar antenna. In the figure, 1.2.3 is the first mixer circuit, 4, 5
．． 6 is the first IF circuit, ? , 8.9 is the second mixer circuit, 10.11.12 is the second IF circuit, 13°14 is the phase detector, 15.16.17 is the combiner, 18.1
9 is a phase shifter, 20.21 is a sample and hold circuit, 22.23 is an A/D converter, 24 is a reference signal generation circuit, 25.26 is a synthesizer, and 27 is a target object, respectively.

Claims (1)

[Claims] A phase matching circuit between the standard receiving system and the other receiving system of an angle detection circuit that detects a phase difference between the output signal of the standard receiving system and each output signal of the other receiving system using a phase detector, a reference signal generation circuit that generates a reference signal and outputs it to the input end of each of the receiving systems; and a reference signal generating circuit that is provided in the signal path of the other receiving system and outputs the reference signal from the phase detector of the angle detection circuit. A phase matching circuit comprising: a phase shifter that corrects a phase difference of the other receiving system in response to a phase difference signal.