JPS6148780A - Monopulse angle measuring receiver - Google Patents

Abstract

PURPOSE:To realize a monopulse angle measuring function only by uniforming amplitude characteristics of receiving circuits of plural systems by determining a deviation angle from the amplitude ratio of the sum and difference signal between monopulse receive signals and then making a level comparison with the signal of a single transmission repetitive signal. CONSTITUTION:The sum SIGMA of and difference DELTA of receive signals from nonopulse antennas of two systems are processed by intermediate frequency mixers 32 and 37, logarithmic amplifiers 34 and 38, an operational amplifier 35, etc., thereby outputting the logarithmic value of the amplitude ratio DELTA/SIGMA of the sum SIGMA and difference DELTA which corresponds to the deviation angle from a real direction. On the other hand, the amplitude ratio of the output of the amplifier 35 and an output which is delayed behind said output through a delay circuit 39 by the single transmission repetition time is compared by a level comparator 40 to determine a deviation direction delta to the real direction. Thus, the monopulse angle measuring function is realized only by uniforming amplitude characteristics of receiving circuits of two systems, etc.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is used in a radar device for capturing and monitoring targets, such as aviation targets, and the present invention is a radar device for acquiring and monitoring targets such as aircraft, and uses and the number of received monopulse angle measurements that provide 1q of highly accurate azimuth information by comparing the amplitude of the difference.

[Technical background of the invention and its problems] Conventionally, the sum and difference of two systems of horizontal antenna patterns,
Regarding monopulse angle measurement receivers that use a corresponding two-system receiving circuit, the circuit shown in Fig. 3 is well known as one used, for example, in a secondary monitoring rake device for aircraft monitoring. There is.

However, with this number of receptions, the received signal Σ obtained from the sum pattern and the received signal Δ obtained from the difference pattern are input and synthesized by the π/2 hybrid 11 provided at the input stage, and the received signal Σ and Δ Two composite signals Σ-jΔ and Δ-jΣ (j is an imaginary number unit) are generated, one having a real part and the other a peak part.

Then, the two composite signals Σ-jΔ and Δ-jΣ are amplified in the high-frequency amplifiers 12 and 13, and mixed with the oscillation signal of equal phase from the Ff ff11 oscillator 16 in the mixer 14-15 to generate Σ-jΔ and Δ-jΣ. The intermediate frequency signals JΔ and -Δ+jΣ are lowered to limiters 19 and 2 by distributors 17 and 18, respectively.
0 and π/2 hybrid 21. The two composite signals Σ-jΔ and Δ-jΣ are shown in FIGS. 4(a) and (b), for example.
) is expressed as a vector as shown in Here, the limiters 19 and 20 are connected to the composite signals Σ-'Δ and -Δ, respectively.
The amplitudes of +jΣ are made constant and supplied to phase comparators 22 and 23, and the π/2 hybrid 21 reproduces the received signal Σ from the two composite signals Σ−jΔ and −Δ+′Σ.

Further, this signal Σ is sent to a distributor 24, a limiter 25, π/
2 hybrid 26 to the phase comparator 22゜23.
and the signal Σ and the composite signal Σ−”Δ and −
After detecting the cosine signal COSφ of each phase difference φ with Δ+JΣ, the two cosine signals COSφ are combined by adding nft327 to obtain the output 2 cosφ=f(Δ/Σ) (function of amplitude ratio Δ/Σ). obtain. In other words, the above phase difference φ(
Figure 4(a).

(b) As shown from It is possible to detect the azimuth angle of

The signal Σ distributed by the distributor 24 is logarithmically amplified and detected by the logarithmic amplifier 28, and is output as a log Σ signal. This signal logΣ is the signal r(
Δ/Σ) is supplied to a processing device connected to a subsequent stage of this reception, and is used for target and azimuth detection processing. Although this monopulse angle measurement receiver 1 is not shown in Fig. 3, (in order to suppress the nightlobe response, it often has a separate reception view for signals 1q from the horizontal omnidirectional antenna pattern. .

By the way, in the monopulse angle measurement receiver using the circuit system as described above, the corresponding circuit sections of the two receiving circuits, namely 12, 13.14, 15.17, 18.19 and 20
and that the amplitude and phase characteristics of 22 and 23 are sufficiently consistent, and that the electrical lengths between each circuit section are sufficiently consistent,
This is an essential condition for highly accurate azimuth detection.

In particular, the high frequency amplifier 12.13-t') mixer 14.1
Active circuit sections such as 5 and intermediate frequency amplifiers must have extremely uniform characteristics. Furthermore, in order to eliminate phase errors, the electrical length between each circuit section needs to be precisely matched in units of mm when the wave layer has a frequency of, for example, about 20 cm. Since the frequency of the received signal usually has a finite bandwidth, it is necessary to check whether the characteristics of each circuit section and between the circuit sections match over the entire bandwidth. Furthermore, in order to minimize fluctuations due to changes in environmental conditions or changes over time after the initial settings, it is necessary to pay close attention to the selection of elements in each circuit and to prepare some kind of compensation circuit in advance. be.

[Purpose of the Invention] This invention was made in consideration of the above-mentioned circumstances, and it is possible to realize monopulse angle measurement accuracy simply by arranging the amplitude characteristics of multiple receiving circuits. It is an object of the present invention to provide a monopulse angle measurement receiver which can be easily designed, adjusted and maintained.

[Summary of the Invention] That is, the monopulse angle measurement receiver according to the present invention calculates the deviation of the target azimuth from the antenna true azimuth from a signal corresponding to the amplitude ratio of the sum signal and the difference signal of received signals obtained from the monopulse antenna. In addition to determining the angle, the levels of signals corresponding to amplitude ratios having a time difference of at least one transmission repetition period are compared, and based on the magnitude relationship, it is determined which side the target is on with respect to the true direction of the antenna. It is something.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 shows its (1) configuration, in which the received signal Σ is amplified by a high frequency amplifier 31, then supplied to a mixer 32 and mixed with a local oscillation signal from a local oscillator 33.
It is down-converted to an intermediate frequency signal. Then, it is logarithmically amplified and detected by the logarithmic amplifier 34 to become a logΣ signal,
The signal is supplied to a subsequent processing circuit (not shown), and is also supplied to one input terminal of an operational amplifier 35, which will be described later.

On the other hand, the received signal Δ is multiplied by j in the high frequency amplifier 36, and then supplied to the mixer 37 where it is mixed with the local oscillation signal from the local oscillator 33 and down-converted to an intermediate frequency signal.

Then, it is logarithmically amplified and detected by a logarithmic amplifier 38, and 1
This becomes a signal of 09Δ and is supplied to the other input terminal of the operational amplifier 35. This operational amplifier 35 extracts a difference signal between the two signals logΣ and logΔ, and its output is supplied to the processing circuit as well as the signal logΣ, and is also supplied to one input terminal of the level comparator 40. The signal is also supplied to the other input terminal of the level comparator 40 via a delay circuit 39 that delays the signal by one repetition period. The level comparator 40 compares the amplitude levels of the output of the operational amplifier 35 and the outputs of the three delay circuits, and divides the output into two levels depending on the magnitude.
It generates a signal δ that is a value and outputs it to the processing circuit.

The operation of the above configuration will be described below.

First, in this reception d, the received signal Σ is sent to the high frequency amplifier 31.
, a signal of log Σ is generated by passing it through the mixer 32 and the logarithmic amplifier 34, while a signal of log Δ is generated by passing the received signal Δ through the high frequency amplifier 36, the mixer 37 and the logarithmic amplifier 38, and the calculation is performed. The amplifier 35 extracts the difference signal between the two signals 109Σ and logΔ. From f0, the output of the operational amplifier 35 is logΔ−logΣ=1
0li 1Δ/Σ1. This signal 10g1Δ/ε1 is similar to the signal f(Δ/Σ) shown in FIG.
From the antenna sum and difference patterns, each (q) is a function of the amplitude ratio of the signal, so the subsequent processing circuit calculates log
If you prepare a reference table in advance so that you can read the deviation angle of the target direction based on the true direction of the antenna from the first axis of Δ/Σ, you will be able to realize the functionality of monopulse angle measurement. . However, here we focus only on the amplitude ratio of Σ and Δ and do not consider maintaining their phase difference, so even if we know the angle of deviation of the target azimuth from the true azimuth of the antenna, we do not know its polarity (±, sign). In other words, it is not known on which side the target direction is relative to the true direction of the antenna.

Therefore, the delay circuit 39 delays the signal 10Q]Δ/Σ1 by one repetition period, and the level comparator 40
The amplitude level is compared with the signal of log lΔ/Σ1 of the next period. Then, depending on the size, a binary signal δ (O or 1) indicating which direction the target direction is located when it is relatively close to the antenna true direction is generated, and
og 1Δ/Σ1 together with the processing circuit.

In other words, the above-mentioned patterns of Σ and Δ are shown, for example, as shown in FIG. When a signal of 10g1△1/Σ1 l based on Δ1 is obtained, after one repetition period, for example, Σ2 in the figure
．． Based on Δ2, a signal (loglΔ2/Σ21) is obtained. Here, the true direction of the antenna approaches the target direction and (1
As the value increases, Σ gradually increases and Δ gradually decreases. In other words, between the signal loglΔ1/Σ1 I and the signal 10g)Δ2/Σ2 I,
There is a relationship lΔ2/Σ21<IQ (IIΔ1/Σ11). If the true direction of the antenna is moving away from the target direction, the opposite relationship to the above holds true.

From this, the output δ of the level comparator 40 is L, 1'' when the output δ of the level comparator 40 is It is on the same side as the direction, and the signal δ is 1 (10g1Δ/
When the Σj signal is larger), it can be determined that the target direction is on the opposite side of the antenna's rotational direction with respect to the antenna's true direction. Generally, the horizontal pattern of the above-mentioned antenna has some asymmetry, so the processing circuit's 10g1Δ
/Σ] A reference table for reading out the deviation angle of the azimuth from the signal is selected according to the value of the signal δ.

Therefore, the monopulse angle measurement receiver configured as described above can realize the monopulse angle measurement function simply by arranging the amplitude characteristics of the two receiving circuits, and also takes into consideration the phase characteristics [i!
Since there is no need to perform the circuit design, adjustment, and maintenance, the circuit can be designed, adjusted, and maintained very easily.

In the above embodiment, the delay amount by the delay circuit 39 was set to one repetition period, but this value is suitable for detecting an amplitude level difference of 10g1Δ, /Σ1 depending on the transmission repetition frequency and the rotational speed of the antenna. You can set it to any interval. In this case, it is more effective to set the delay time manually or automatically using the electronic instrument 1 or the like.

Furthermore, the logarithmic amplifiers 34 and 38 may be replaced by linear amplifiers having a required dynamic range. In this case, it is assumed that the arithmetic amplifier 35 has the function of a divider. Furthermore, the logarithmic (or linear) amplifier 34.3
The output of the operational amplifier 35, the three delay circuits, and the level comparator 40 may be implemented as digital circuits, and the above operation may be performed by digital processing. Analog in the rear stage
A digital converter may be provided so that the functions of the delay circuit 39 and the level comparator 40 are realized by a digital circuit.

In the above embodiment, an example of two systems of antenna patterns and a receiving circuit is used for convenience of explanation, but the same effect can be obtained even if the present invention is applied to a monopulse angle measurement receiver having three or more systems of antenna patterns and receiving circuits. Needless to say, it is possible.

[Effect of the invention] As detailed above, according to this invention,? ! It is possible to realize monopulse angle measurement (geometry) by simply arranging the amplitude characteristics of two or more receiver circuits, which allows design 1.
J,! It is possible to provide a monopulse angle measurement receiver which can be easily adjusted and maintained.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram showing another embodiment of monopulse angle measurement reception according to the present invention, Fig. 2 is a diagram for explaining the operation of the same embodiment, and Fig. 3 is a conventional monopulse angle measurement reception example. FIG. 4 is a block circuit diagram showing the configuration of the receiver, and is a diagram for explaining the operation of the receiver. 11, 21.2G...π/2 hybrid, 12.1
3.31゜36...High frequency amplifier, 14.15.32
．． 37... Mixer, 16° 33... Local oscillator, 1
7.18.24...Distributor, 19.20°25...
Limiter, 22.23... Phase comparator, 27... Adder, 28, 34.311... Logarithmic amplifier, 35...
- Operational amplifier, 39...Delay circuit, 40...Level comparator.

Claims (1)

[Claims] a first means for deriving a signal corresponding to the amplitude ratio of the sum signal and the difference signal of the received signals obtained from the monopulse antenna to determine the deviation angle of the target azimuth with respect to the antenna true azimuth; A monopulse angle measurement receiver comprising: second means for comparing the levels of signals corresponding to the amplitude ratios having a time difference to determine the direction of the target with respect to the antenna true direction.