JPS60239685A - Secondary radar equipment - Google Patents

Abstract

PURPOSE:To suppress the generation of a dummy target by a side lobe and a circumferential reflector, by respectively transmitting both pulse signals of a question and side lobe suppressing (SLS) control from a secondary radar apparatus through a sum/difference system antenna and a SLS control antenna. CONSTITUTION:In a emission pattern chart of the sum pattern 103 and difference pattern 104 of a sum/difference system antenna and the emission pattern 105 of an SLS antenna, when an aircraft is positioned at the azimuth of a direction line 107, the level of the emission pattern 105 of the SLS antenna becomes large as compared with the side lobe of the sum/difference system antenna and the arrival level of an SLS control pulse signal becomes larger than that of a question pulse signal. In a receiving apparatus, the question pulse signal is judged as the question pulse by the side lobe of the sum pattern other than main beam and the prohibition gate of a predetermined time is formed and the reception of the question pulse signal on and after is prohibited. Therefore, a dummy target by the side lobe of the sum pattern is suppressed. Further, the prohibition gate is formed even when a reflector is interposed around a secondary radar apparatus and the dummy target by the circumferencial reflector is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a secondary radar device, and particularly to a secondary radar device that improves the suppression function against pseudo targets caused by side ropes, peripheral reflectors, etc. .

(Conventional technology) Conventionally, for example in air traffic control systems.

By linking with the transponder installed on the aircraft,
In secondary radar devices operated for the purpose of identifying aircraft and acquiring altitude information, various side rope suppression methods or pseudo target suppression methods are used to remove pseudo targets, for example, The 3-pulse SL8 system and the improved fj18L8 system are well known as well-known systems.

However, as is generally known, each of these methods has drawbacks that require improvement, and one solution to these problems is, for example, by increasing the width of the image of a response signal from an aircraft on a radar scope. Ru. An improvement factor of reducing so-called blips was also taken into consideration.

Secondary radar equipment equipped with the new SL8 method is being put into practical use.

This new secondary radar equipment consists of an interrogating antenna and an 8L
As the 8 antenna, a sum-difference antenna, which is well known as a so-called monopulse antenna, was used.

Compatible with transponders installed on aircraft. Regarding the transmission and reception of question pulse signals and response pulse signals,
The sum pattern of the sum-difference antenna is mainly used, and when transmitting the SL8 control pulse signal to the transponder, the difference pattern is used to improve blips and suppress the generation of false targets due to side lobes. There is.

In the above-mentioned secondary radar device using the sum-difference antenna, an interrogation consisting of P, pulse and P, pulse as shown in FIG. pulse signal.

A difference pattern 102 is transmitted to a transponder on board an aircraft and is shown in FIG.
Through the P shown in FIG. 2(b) K.

SL8 control pulses consisting of pulses at the same time.

It is sent to the transponder. In the transponder, the above interrogation pulse signals (PI, PM
) and the 8L8 control pulse signal (P, ) and %P1
Compare the levels of the pulse and P, and if the level of p, -p does not exceed 4.5 dB, it is determined that the interrogation pulse signal is an interrogation pulse signal due to a side lobe outside the main beam in the sum pattern. Approximately 3
A 5 μs inhibit gate will be generated to inhibit reception of further interrogation pulse signals, thus corresponding to the "transponder response range" shown in FIG. Japanese pattern 1
Only in a limited angular range in the 01 main beam is a predetermined response pulse signal sent back from the transponder to the secondary radar device.

That is, the main beam width in the sum pattern is substantially compressed, the blip is improved, and through the coverage effect of the one-difference pattern on the side ropes of the sum pattern, the inhibition in the same transponder as above is improved. The gate signal also blocks response pulse signals corresponding to the side lobe regions of the sum pattern, suppressing pseudo targets due to side lobes.

However, even in the secondary radar device using the sum-difference antenna described above, the difference pattern cannot completely cover the side ropes of the sum pattern, so pseudo targets due to the side ropes of the sum pattern are completely suppressed. It is difficult to do so.

In particular, there is a drawback that pseudo targets are generated due to side ropes on both sides of the main beam of the sum pattern. Further, the difference pattern is generally as follows.

Especially since it does not exhibit effective omnidirectionality.

At an azimuth angle of approximately 90 degrees with respect to the main beam of the sum pattern, the level tends to be lower than that of the side rope of the sum pattern. In the case where a peripheral reflector is present in an angular range where the pointing azimuth angle deviates by around 90 degrees.

A disadvantage is that a false target of the aircraft is generated via this peripheral reflector.

(Objective of the Invention) The object of the present invention is to eliminate the above-mentioned drawbacks and create a secondary radar system using a sum-difference antenna! - To provide a secondary radar device provided with an SL8 function that effectively suppresses the generation of false targets due to side ropes and peripheral reflectors.

(Structure of the Invention) The secondary radar device of the present invention is a secondary radar device provided with a side rope suppression function, and at the time of transmission, at least transmits an interrogation pulse signal to a transponder mounted on a predetermined target object. Acts as a credit, and at least upon receipt.

A sum-difference force that forms a response signal returned from the transponder (a sum pattern that functions for receiving a lus signal) and a difference pattern that functions for receiving a lus signal (at least the response) at the time of reception. and at least an S for the transponder during transmission.
L 8 (5ide Lobe8trppressi
on Near-lobe suppression) Functions for transmitting control pulse signals. The antenna is equipped with an omnidirectional or semifocal directional SLS antenna.

(Example of the invention) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 3 is a partial block diagram of an embodiment of the present invention, showing only essential parts necessary for explaining the present invention.

As shown in FIG. 3, the uninvented secondary radar device is
Wadashi method antenna 1 which mainly functions as an interrogation antenna
, 8L8 antenna 2 with omnidirectional or semi-focal directivity,
A transmitting device 3, a transmitting/receiving switch 4, a receiving device (■) 5,
It is equipped with a receiving device (■) 6 and a response pulse signal output circuit 7.

In FIG. 3, an interrogation pulse signal (pttpm) consisting of a bP1 pulse and a P pulse is sent from the transmitting device 3;
An 8L8 control pulse signal (p,,p,) consisting of a P1 pulse and a P, pulse is output at a predetermined timing via a specific carrier wave. The interrogation pulse signals (p, , p3) are input to the sum system power supply terminal 51 of the sum system antenna 1 via the transmission/reception switch 4 and the sum system power supply line 110, and form a sum pattern including the main beam. It is emitted in the form of In addition, the SL8 control pulse signal (P
I, P2) are directly input to the 8L8 antenna 2 and radiated. The above interrogation pulse signal (pttpa) and S
L8 control pulse signal (Pl.

pt) pulse waveform diagrams are shown in Figures 4(a) and (b).
are shown respectively. As mentioned above, from the secondary radar device, the sum-difference antenna 1
and an interrogation pulse signal (P,, P3) and an SL8 control pulse signal (pt, P3) transmitted via the 8LS antenna 2.
ps) is received by a transponder on board the aircraft, and generally indicates the azimuth position of the aircraft;
In relation to the radiation patterns of the sum-difference antenna 1 and the SLS antenna 2, the interrogation pulse signals (Pl, P
8) and SL8 control pulse signals (pl, pt), the incoming levels at the transponder will have a relative difference.

FIG. 6 is a radiation pattern diagram showing the relative relationship between the sum pattern 103 and difference pattern 104 of the sum-difference antenna 1 and the radiation pattern 105 of the 8L8 antenna 2. In FIG. 6, when the aircraft is located in the direction of the direction line 106, the interrogation pulse Signal (pt
, P8) has a higher incoming call level! l1% From the transponder, the interrogation pulse signal (pi, ps
) is sent back to the secondary radar device. This response pulse signal is received by the sum-difference antenna 1 in FIG. 110 and the transmission/reception switch 4, the signal is input to the receiving device (I) 5. On the other hand, the differential system response pulse signal (C)P, ) received via the difference pattern 104 is sent to the receiving device (II
) is input into 6. In the receiving device (I) 5 and the receiving device (■) 6, the above response signals (OPr) and (OPr) are received and demodulated, respectively, and are converted into response pulse signals (OPr) and (C)Pr in the video frequency band. ) and input to the response pulse signal output circuit 7. In the response pulse signal output circuit 7, the levels of the response pulse signal (OPr) and (C)Pr) are compared,
Similar to the previous case shown in FIG.
Only when the level of OPr) exceeds a predetermined level value, it is determined that a response signal has been received by the main beam of the sum pattern, a predetermined response signal is output, and a predetermined data processing device sent to. Of course, (OPr”
) -(C)Pr) is less than the above-mentioned predetermined level value, the response pulse signal output circuit 7 cuts off and does not output it. Due to this effect, a predetermined response noise signal is output only in a limited angular range of the main beam of the sum pattern, the main beam width is substantially compressed, and blurring is improved.

Next, in FIG. 6, when the aircraft is located in the direction of the direction line 107, the radiation level of the radiation pattern 105 of the 8L8 antenna 2 is higher than the zydrope Φ level of the sum-difference antenna 1. Since the incoming signal level at the transponder installed on the aircraft is large, the interrogation pulse signal (P, , P
, ), the level due to the S L 8 control pulse signal (P□, P) radiated from the 8L8 antenna 2 is higher than the level due to the interrogation pulse signal cP, , P, ) and SL8 control pulse signal (p
The incoming pulse signal waveform diagrams of t and pt) are shown in FIGS. 5(a) and 5(b), respectively. In this way, when the incoming level of the K8L8 control pulse signal (P, , P, ) becomes larger than the incoming level of the interrogating pulse signal (P, , P, ) and exceeds a predetermined level value, The interrogation pulse signal (P+-Pa) is determined to be an interrogation pulse signal due to the side rope outside the main beam of the sum pattern, and a prohibition gate of approximately 35 μS is generated, prohibiting reception of interrogation pulse signals thereafter. be done. The correspondence between the waveform line of the inhibit gate, the interrogation pulse signal (P+-Ps), and the BT, 8 control pulse signal (Pl, P,) is shown in FIG. 5(C). As a result, the transponders do not send a predetermined response signal back to the secondary radar, and therefore, pseudo targets due to the side lobes of the sum pattern are suppressed. Moreover.

Since the side ropes of the sum pattern 103 are covered over the corresponding all azimuth angle area by the omnidirectional or quasi-directive radiation pattern 105 by the SLS antenna 2, the side ropes themselves can be used to detect pseudo targets. All occurrences are suppressed.

On the other hand, in a state where some kind of reflector is present around the secondary radar device, for example, in FIG. 6, a peripheral reflector is present in the direction of the direction line 106,
If the aircraft is located in the direction of FIG. 5(a), as in the previous case.

As shown in (b) and (C), SLS aerial sheath 2
The SL8 control pulse signal (Pl.

The incoming level of P, ) (see FIG. 5(b)) is the interrogation pulse signal (Pl.

If L is larger than the incoming level of P, ) (see Fig. 5(a)), and this level difference exceeds a predetermined level value, then, as in the previous case, a pulse of about 35 μs corresponding to the pulse P, A prohibition gate (see FIG. 5C) is generated, and subsequent reception of interrogation pulse signals is prohibited. On the other hand, it becomes a factor in the occurrence of pseudo targets. The interrogation pulse signal (p, -PM) radiated through the main beam of the sum pattern 103, reflected by the peripheral reflector, and sent to the aircraft corresponds to the increment in the propagation path length due to one reflection. The timing of arrival at the transponder on board the aircraft is delayed from the interrogation pulse signal (ps, pm) shown in FIG. 5(a) by a time corresponding to the increment in the propagation path length. Therefore, due to the above-mentioned prohibition gate of about 35 μs (see FIG. 5(C)), reception of the interrogation pulse signals (P, , PM) reaching the aircraft via the peripheral reflector is prohibited, and the corresponding No response signal is sent back.

In other words, all occurrences of false targets due to peripheral reflectors are suppressed.

(Effects of the Invention) As described in detail above, the present invention provides a secondary radar system equipped with a sum-difference antenna, which can maintain the improvement of the big corresponding to the main beam while also preventing pseudo targets and peripheral reflectors due to side lobes. This has the effect of effectively suppressing pseudo-targets caused by this, and achieving the intended monitoring function without any problems.

[Brief explanation of drawings]

! Figure 1 shows the sum-difference pattern of the sum-difference antenna, and Figure 2 (
a) and (b) are the interrogation pulse signal and 8L8, respectively.
A pulse waveform diagram of a control pulse signal, FIG. 3 is a partial block diagram of an embodiment of the present invention, and FIGS. 4(a) and (b) are
FIG. 5 is a pulse waveform diagram of an interrogation pulse signal and an 8L8 control pulse signal, each applied to an embodiment of the present invention.
)e (b) and (C) are waveform diagrams of an incoming interrogation pulse signal, an incoming SL8 control pulse signal, and an inhibit gate, respectively, and a horizontal pattern diagram of the Japanese-difference antenna and the 8L8 antenna. In the figure, 1...
Wa-difference antenna, 2...SLS antenna, 3...
...Transmission device 6, 4...Transmission/reception switch, 5.
...Receiving device ff1 (1), 6...Receiving device (Ill, 7...Response pulse signal output circuit. Deaf j ＾ ρ 碌 j

Claims (1)

[Claims] A secondary radar device provided with a side rope suppression function. At the time of transmission, it functions at least to transmit an interrogation pulse signal to a transponder mounted on a predetermined target object, and at the time of reception, it functions at least to receive a response pulse signal returned from the transponder. and at least the sum pattern at the time of reception.
a sum-difference antenna forming a difference pattern serving for reception of the response pulse signal;
ssion: Functions for transmitting control pulse signals (sideloop suppression). A secondary radar device comprising: an omnidirectional or semifocal directional SLS antenna.