JPH0511587B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an angular difference detection circuit that detects an angular difference between a set angle of a radar antenna used in a monopulse radar and an angle of a target object, and particularly relates to an angular difference detection circuit that detects an angular difference between a set angle of a radar antenna used in a monopulse radar and an angle of a target object. The present invention relates to an angle difference detection circuit that is an improved phase difference detection circuit for defining the direction of a target object in the circuit.

The angular difference detection circuit used in monopulse radar calculates the sum signal obtained by adding the received signal levels received from the target object by the two radar antennas A and B, which have the same beam characteristics, and the subtracted difference signal. are input into two series of circuits, and the receiving frequency of 9GHz is lowered to 10MHz, and
The angle difference signal is obtained by amplifying the signal to a predetermined level and using the amplified 10 MHz sum signal as a reference to detect the level difference and phase delay and lead between the sum signal and the difference signal.

This angular difference signal becomes a voltage that specifies the angular difference between the set angle of the radar antenna and the angle of the target object in accordance with the detection level difference, and becomes a positive potential when the detection phase is delayed, and negative when the detection phase is advanced. The potential determines whether the target object is on the A antenna side or the B antenna side.

In this angle difference detection circuit, if the gain and phase between the two series of circuits differ, the level difference and phase difference of the received input signals will be different, making it impossible to obtain the accurate angle and direction of the target object. .

The gain between the two series of circuits is kept constant by the amplifier circuit AGC operation, but the phase shift needs to be adjusted so that each circuit and each series are all 0, which takes a lot of adjustment man-hours, so phase adjustment is omitted. There is a need for an angle difference detection circuit that can detect the difference in angle.

[Conventional technology]

FIG. 2 is a block diagram of a conventional angular difference detection circuit, and FIG. 3 is a pattern diagram for explaining the operation of a monopulse radar antenna. Referring to the figure, input signals to the angle detection circuit will be explained.

In Figure 3, A has the same beam characteristics.
The antenna setting direction of the two antennas and B is
0 and are arranged so that they overlap at 1/2 the output level of the maximum point of the antenna beam. For example, 〓1
When a target object in the direction is received by antenna A and antenna B, the reception levels become L and R. The sum and difference signals of the received signals, that is, L+R,L
After creating the two signals -R, they are input to the two series of circuits shown in FIG. 2, respectively.

In each of the two series circuits, first mixer circuits 1 and 2 step down the input signal frequency of 9 GHz to 330 MHz, and first intermediate frequency amplifier circuits (hereinafter referred to as IF circuits) 3 and 4 step down the input signal frequency to 330 MHz. amplify,
The second mixer circuits 5 and 6 further step down the signal to 10 MHz, and the second IF circuits 7 and 8 amplify it to a predetermined level, which is then output to the phase detector 9.

The phase detector 9 compares the L+R and LR signals in the 10 MHz band output from each series circuit, detects the level difference and phase difference between the two signals, and generates a signal having a voltage corresponding to the level difference. The potential of the signal is output as a positive potential if the phase difference is delayed, and as a negative potential if it is advanced. This output voltage has an angular difference of 1 as shown in FIG. 3, with the negative potential defining the R direction and the positive potential defining the L direction.

[Problem that the invention seeks to solve]

In the above-described angular difference detection circuit, if there is a phase shift in the mixer circuit or IF circuit that constitutes the circuit, the phase of the input received signal will change, making it impossible to obtain an accurate detected phase difference. Therefore, in the past, the phase shift was brought close to 0 for each circuit, and the phase of each circuit was corrected for each series to reduce the phase shift to 0.
It was. This phase correction work becomes more difficult as the number of circuit stages increases, and requires a considerable number of man-hours.

[Means for Solving the Problems] The present invention provides an angular difference detection circuit that solves the above problems, and the means includes a first mixer circuit that down-levels a received high-frequency signal; The first
a first intermediate frequency amplification circuit that amplifies the signal from the mixer circuit; a second mixer circuit that downshifts the signal from the first intermediate frequency amplification circuit;
It is equipped with two circuits connected in series, a second intermediate frequency amplification circuit that amplifies the signal from the mixer circuit, and a detection circuit that detects the signal from the second intermediate frequency amplification circuit, and detects the sum signal of the monopulse radar. and a comparison circuit that compares the amplitudes of the output signals of the two series of detection circuits;
A phase inversion circuit to which the output signal from the comparator circuit is added, and a phase detection unit that detects the phase difference between two correction signals created by limiting the amplitude of the outputs of the first mixer circuits of the two series with respective limiter circuits. an angular difference detection circuit configured to control the phase inversion circuit according to the detection result of the phase detection circuit, and set the potential polarity of the output potential of the comparison circuit in accordance with the detected phase shift. It will be done.

[Effect]

A first mixer circuit, a first intermediate frequency amplification circuit, a second mixer circuit, a second intermediate frequency amplification circuit, and a detection circuit are connected in series. The frequencies of the two input received signals are lowered to the IF frequency and amplified by a predetermined amount, and the amplified IF signals are detected by each detection circuit. Both detected signals are input to a comparator circuit, a level difference between the two detected signals is detected, and the detected signal is outputted via a phase inversion circuit.

In addition, after the level of the output signal of each first mixer circuit of the two-series circuit is made constant by a limiter circuit, the phase difference between the output signals of each first mixer circuit is detected by a phase detection circuit, and the detected phase difference is controls the phase inversion circuit to define the potential of the output signal of the comparison circuit to be a positive potential or a negative potential.

In other words, the angular direction is obtained by detecting the phase difference between the output signals of the first mixer circuits in the first stage of the two-series circuit and defining the level difference signal representing the angular difference as a positive potential or a negative potential. This is a practical method that eliminates the need for adjusting the phase shift for each circuit and each series as in the past.

〔Example〕

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

FIG. 1 is a block diagram of an angular difference detection circuit according to an embodiment of the present invention, and the same parts as in FIG. 2 are designated by the same reference numerals.

As shown in the block diagram of FIG. 1, the angle detection circuit of one embodiment includes first mixer circuits 1 and 2.
, a two-series circuit in which first IFs 3 and 4, second mixer circuits 5 and 6, second IIF circuits 7 and 8, and detection circuits 11 and 12 are connected in series, and a detection circuit. A comparison circuit 10 that compares the frequency signals of the first mixer circuits 1 and 12, a phase inversion circuit 13 connected to the comparison circuit 10, and limiter circuits 14 and 15 that maintains the output signal level of the first mixer circuits 1 and 2 at a constant level. , limiter circuit 1
The phase detecting circuit 16 detects the phase difference between the output signals of the output signals 4 and 15, and controls the phase inverting circuit 13 using the detected phase difference signal.

The movement was received by the radar antenna.
The 9 GHz L+R signal and LR signal are down-converted to 330 MHz by the first mixer circuits 1 and 2, amplified by the first IF circuits 3 and 4, and then again by the second mixer circuits 5 and 6.
The signal is stepped down to 10 MHz, amplified by a predetermined amount by second IF circuits 7 and 8, and detected by detection circuits 11 and 12, respectively. Detection circuits 11 and 1
The levels of both signals detected by 2 are compared by a comparison circuit 10, and a level difference is detected and outputted via a phase inversion circuit 13. Note that in order to obtain an accurate level difference between the received signals, the gain is maintained constant by the AGC operation of the two series circuits.

On the other hand, the output signals of the first mixer circuits 1 and 2 are kept at a constant level by the limiter circuits 14 and 15, respectively, and the phase detection circuit 16 detects the phase difference between the two signals. This detected phase difference signal is input to the phase inversion circuit 13 and controls the operation of the phase inversion circuit 13. That is, when the phase of the signal from the L antenna detected by the phase detection circuit 16 is ahead of the phase of the signal from the R antenna, the phase inversion circuit 13 is operated so that the output signal of the comparison circuit 10 has a negative potential, In the opposite case, the phase inversion circuit 13 is operated so that the output signal of the comparator circuit 10 has a positive potential, and the level difference signal representing the angular difference is defined as a negative potential or a positive potential to obtain the direction of the target object. There is.

〔Effect of the invention〕

As described above, according to the present invention, only the phase adjustment of the first mixer circuit eliminates the need to adjust the phase shift between each circuit and each series in the related art, and the number of adjustment steps can be significantly reduced.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an angular difference detection circuit according to an embodiment of the present invention, Fig. 2 is a block diagram of a conventional angular difference detection circuit, and Fig. 3 is a pattern diagram for explaining the operation of a monopulse radar antenna. be. In the figure, 1 and 2 are first mixer circuits, 3,
4 is the first IF circuit, 5 and 6 are the second mixer circuits,
7 and 8 are second IF circuits, 9 is a phase detector,
10 is a comparison circuit, 11 and 12 are detection circuits, 13 is a phase inversion circuit, 14 and 15 are limiter circuits, and 16
indicate phase detection circuits, respectively.

Claims (1)

[Claims] 1. A first mixer circuit that down-levels a received high-frequency signal, a first intermediate frequency amplification circuit that amplifies the signal from the first mixer circuit, and a first intermediate frequency a second mixer circuit that steps down the signal from the amplifier circuit, a second intermediate frequency amplification circuit that amplifies the signal from the second mixer circuit, and detects the signal from the second intermediate frequency amplification circuit. A comparison circuit that compares the amplitude of the output signals of the two series of detection circuits, and a comparison circuit that compares the amplitude of the output signals of the two series of detection circuits; and a phase detection circuit for detecting a phase difference between two correction signals produced by amplitude-limiting the outputs of the first mixer circuits of the two series with respective limiter circuits. , An angle difference detection characterized in that the phase inversion circuit is controlled based on the detection result of the phase detection circuit, and the output potential of the comparison circuit is set to a positive or negative potential corresponding to the detected phase difference. circuit.