JPH01248085A - Receiving display apparatus for tracking radar - Google Patents

Abstract

PURPOSE:To make receiving display effective, by providing a first amplifier containing an automatic gain control circuit leaving the amplitude change due to an angular error while removing the amplitude change caused by other factor from the Doppler signal received by a Doppler radar receiving circuit. CONSTITUTION:A tracking notch filter 10 is in synchronous relation to a speed gate 6 and outputs a signal while removes the high level signal dominating the AGC circuit in a first tracking amplifier 5. Therefore, the remaining low level signal is amplified by a second Dopper amplifier 11 to obtain a sufficient S/N ratio. The spectrum of this signal is displayed on a second spectrum display device 12. In this case, when a target transmits a false signal and the frequency of said false signal is changed, the speed gate 6 begins to track the false signal. Whereupon, the spectrum 13 displayed on a first spectrum display device 9 is shifted from a broken line to a solid line in its frequency and the spectrum 14 of the echo signal of a real target is displayed on a second spectrum display device 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radar reception display device for tracking a target with a Doppler radar.

[Conventional technology]

In order to track a target with Doppler radar, it is necessary to detect the difference between the pointing direction of the radar and the target direction, that is, the angular error.On the other hand, the received signal level of the radar depends on not only the angular error, but also the distance to the target and the target radar. It changes depending on conditions such as cross-sectional area. Therefore, in order to accurately detect the angular error, it is necessary to normalize the signal level so that the strength or weakness of the signal level is caused only by the angular error. An automatic gain control i (AGC) circuit is used to normalize the signal level.

As an example of this, FIG. 4 shows the configuration of a Cl1l tracking radar using conical scanning. A continuous wave (C
The Doppler signal of the target echo is received by the receiving antenna 1 and converted to an intermediate frequency by the mixer 2.

The Doppler signal is amplified by an intermediate frequency (IF) amplifier 3 and subjected to signal processing by a mixer 4. The Doppler amplifier 5 includes an AGC circuit, and the Doppler signal is kept at a constant level regardless of the distance to the target or the radar cross section by the AGC circuit, but the level changes proportional to the angular error due to conical scanning. For the Doppler signal that has reached a certain level as described above, the frequency spectrum display 9 displays the Doppler frequency fd on the horizontal axis and the S/N ratio on the vertical axis. On the other hand, the Doppler signal is input to the speed gate 6. The speed gate 6 has a function of switching between a search mode and a tracking mode, and in the search mode it works as a narrow band filter that moves across the Doppler frequency band.
When the position of the narrowband filter matches the Doppler frequency of the input signal, it locks to the input signal and performs automatic frequency adjustment (AFC).
The circuit tracks the frequency of the signal to obtain target speed information and improve the S/N ratio of the input signal.The signal that has passed through the speed gate 6 is detected by the angle error detector 7, which detects the signal generated by conical scanning. Error signals in the azimuth and elevation angles are detected from the fluctuations in the level, and are input to the antenna servo circuit 8. Driven by the antenna servo circuit 8, the directions of the antennas 1 and 16 are controlled to eliminate error signals, and the target is tracked.

Target 2 being tracked by the Dotsupura radar mentioned above, such as an airplane, is used as a deceptive interference in order to prevent radar tracking.
u1l Off: VGPO) is used. VGPO is a system that interferes with Doppler radar by airplanes, etc. When an airplane, etc. receives the radio waves transmitted by Doppler radar, it amplifies the radio waves of that frequency and sends them back to the radar as a deceptive signal. Since the input level of this deceptive distance signal is sufficiently stronger than the echo signal of the true target, the radar side that receives it shifts.

The AGC circuit in the Doppler amplifier 4 normalizes the received signal at the false signal level, and the true target echo signal, which has a low signal level, cannot obtain a sufficient S/N ratio and is erased. Since the frequency of the deceptive distance signal shifts, the speed gate 6 tracks the deceptive signal in frequency rather than the true target. If the transmission of the deception signal is stopped when the frequency of the deception signal becomes considerably distant from the Doppler frequency of the true target, the speed gate 6 will stop tracking the input signal and return to the search mode. In other words, the radar loses sight of the target and has to start searching for the target all over again.

[Problem to be solved by the invention]

As described above, the conventional Doppler radar has a drawback in that when there are a plurality of input signals, input signals with relatively low levels are erased by the AGC circuit.

The present invention eliminates the above-mentioned drawbacks and provides countermeasures against electronic weapons (Electronic weapons).
tronic Counter+5easuras:
In order to counter ECM), so-called electronic counter-countermeasures (Electronic Counter-Countermeasures)
The present invention provides an effective reception display device for a tracking radar as a means of ECCM).

[Means to solve the problem]

A reception display device for a tracking radar according to the present invention for solving the above problems will be explained with reference to FIG. 1 corresponding to an embodiment.

The device of the present invention shown in the figure is a device that tracks and receives and displays a target using a Doppler radar, and removes amplitude changes due to other factors from the Doppler signal received by the Doppler radar receiving circuit, leaving amplitude changes due to angular errors. A first amplifier 5 including an automatic gain control circuit, a first spectrum display 9 that displays the frequency of the Doppler signal output from the first amplifier 5, and a first spectrum display 9 that displays the frequency of the Doppler signal output from the first amplifier 5. A speed gate 6 searches for a frequency, locks to the searched frequency and tracks the frequency, and tunes to the speed gate 6 to remove the frequency tracking signal from the Doppler signal received by the Doppler radar receiving circuit. a notch filter 10, a second amplifier 11 that amplifies and outputs the output from the notch filter 10, and a second spectrum display 12 that displays the frequency of the Doppler signal output from the second amplifier 11. have.

[Effect]

In the above device, only the level fluctuation caused by the difference between the pointing direction and the target direction, that is, the angular error, is left in the Doppler signal received by the Doppler radar receiving antenna 1, and the level fluctuation caused by other factors is detected by the AGC circuit of the first amplifier 5. Since the angular error is removed, the angular error is accurately detected, and the frequency of the Doppler signal is displayed on the first spectrum display 9. On the other hand, the Doppler signal received by the Doppler radar receiving antenna 1 is outputted from the mixer 4 to the notch filter 10 tuned to the speed gate 6, removes the signal frequency-tracked by the speed gate 6, and transmits it to the second amplifier 11.
is amplified and displayed on the second spectrum display 12. Therefore, this tracking radar reception display device can display two different reception signals.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit block diagram of a tracking radar reception display device to which the present invention is applied. In the figure, 1 is a receiving antenna, 2 is a mixer, 3 is an intermediate frequency (IF) amplifier for the received signal, and 4
is a mixer, 5 is the first Doppler amplifier including the AGC circuit, and 6 is a narrowband tracking filter (speed gate).
, 7 is an angle error detector, 8 is an antenna servo circuit, 9 is a first frequency spectrum display, 10 is a tracking notch filter, 11 is a second Doppler amplifier, 12 is a second frequency spectrum display, and 15 is a transmitter. 16 is a transmitting antenna. Among the above configurations, antenna 1, mixer 2, IF amplifier 3, mixer 4, Doppler amplifier 5.
The speed gate 6, the angle error detector 7, the antenna servo circuit 8, the spectrum display 9, the transmitter 15, and the transmitting antenna 16 are the same as those shown in FIG.

The Doppler signal processed by the mixer 4 is input to the first Doppler amplifier 5, while the tracking notch filter l
Enter O. The tracking notch filter 10 is tuned to the speed gate 6 and the first Doppler amplifier 5
The high level signal that dominated the internal AGC circuit is removed and output. Therefore, the remaining low level signal is amplified by the second Doppler amplifier 11 to obtain a sufficient S/N ratio. The spectrum of this signal is displayed on the second spectrum display 12.

If the target being tracked by the above Doppler radar display, such as an airplane, is not transmitting a VGPO deceptive @ signal,
Even if a deceptive separation signal is being transmitted, if the frequency of the deceptive separation signal and the frequency of the true target Doppler signal are the same, a spectrum 13 will be displayed on the first spectrum display 9 as shown in FIG. , no spectrum is displayed on the second spectrum display 12. When the target transmits a deceptive fighting signal and changes the frequency of the deceptive i-signal, the speed gate 6 starts tracking the deceptive fighting signal. Then, as shown in FIG. 3, since the spectrum 13 displayed on the first spectrum display 9 is the spectrum of the false signal, it is shifted from the frequency indicated by the chain line to the frequency indicated by the solid line, and the spectrum 13 displayed on the second spectrum display 12 is shifted from the frequency indicated by the chain line to the frequency indicated by the solid line. The spectrum 14 of the true target echo signal is displayed. Therefore, the operator can easily detect the effect of the VGPO.

At this time, the operator operates the automatic frequency adjustment circuit of the speed gate 6.
The speed gate 6 can be prevented from returning to search mode by turning off trol:AFC:) and manipulating the position of the narrow band filter so that the spectrum 13 displayed on the first spectrum display 9 disappears. .

When a target being tracked by the Doppler radar, for example a fighter-bomber, launches a missile and attacks, the Doppler radar receives both the missile's echo signal and the target's echo signal. The missile echo signal, which is at a lower level than the target echo signal, is erased by the AGC circuit of the Doppler amplifier 5 and is not displayed on the first spectrum display 9, but because it passes through the notch filter 6, it is displayed on the second spectrum display. 12 is displayed. On the other hand, since the target echo signal has a high S/N ratio, it is amplified by the Doppler amplifier 5 and displayed on the first spectrum display 9. This allows the operator to know that the target is launching a missile attack. Especially if this missile is an anti-radar missile guided by the main beam of a Doppler radar, if you set the AFC of the speed gate 6 to memory mode and gradually shift the antenna 1 from the direction of the target being tracked, the first spectrum display The display on device 9 disappears,
Since only the display on the second spectrum display 12 remains, it is also possible to determine whether or not it is an anti-radar missile. When it is determined that it is an anti-radar missile, the antenna can be instantly returned to its original position to drive the anti-radar missile out of the main beam, causing damage caused by the anti-radar missile without interfering with the original target tracking. can be prevented.

〔Effect of the invention〕

As explained above, the tracking radar reception display device to which the present invention is applied can display two reception signals with different levels. Therefore, even if the target being tracked uses VGPO, its deceptive distance signal can be detected. Additionally, if the system receives a missile attack from a target it is tracking, this will be immediately displayed and the missile can be detected. In addition, it is possible to quickly and accurately judge the type of missile, and it is possible to respond appropriately and quickly to the threat of these missiles, such as by launching an interceptor missile.

In other words, the tracking radar reception display device of the present invention can effectively counter ECM from both hardware and software aspects.
It becomes a means of M.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the tracking radar reception display device of the present invention, FIGS. 2 and 3 are diagrams showing display examples of the above device, and FIG. 4 is a block diagram of a conventional tracking radar reception display device. It is a block diagram. l...receiving antenna? , 4...Mixer 3...I
F amplifier 5...First Doppler amplifier 6...Speed gate 7...Angle error detector 8...Antenna servo 9/12...Spectrum display 10...Notch filter 11...No. 2 Doppler amplifiers 13, 14...spectrum 15...transmitter 16
...Transmission antenna patent applicant Nichihe Musen Co., Ltd.-4'l

Claims (1)

[Claims] 1. A device that tracks a target using a Doppler radar, receives and displays the target, and from a Doppler signal received by a Doppler radar receiving circuit,
a first amplifier including an automatic gain control circuit that leaves amplitude changes due to angular errors and removes amplitude changes due to other factors; and a first spectrum display that displays the frequency of the Doppler signal output from the first amplifier. Similarly, the first
A speed gate that searches the frequency of the Doppler signal output from the amplifier, locks to the searched frequency and tracks the frequency, and a signal that the speed gate tracks the frequency from the Doppler signal received by the Doppler radar receiving circuit. a notch filter tuned to the speed gate to remove
A reception display device for a tracking radar, comprising: an amplifier; and a second spectrum display device that displays the frequency of the Doppler signal output from the second amplifier.