JPH0254910B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radar system featuring a video integration system section.

The video integration method of radar equipment takes advantage of the periodic nature of the received signals reflected from targets such as aircraft to improve the S/N ratio (signal-to-noise ratio) and reduce interference caused by unnecessary signals. The purpose is to

As shown in Fig. 1, the received signal input signal reflected from the target is supplied to a delay circuit 3 via a switch 1 that uses video integration and non-video integration, and an adder 2. is delayed by one period, and the multiplier 4 adds the feedback coefficient K (0<K
<1) and the next arriving signal are added together in an adder 2. If this is repeated one after another, the target signals will be added linearly. On the other hand, since noise and interference signals do not have periodicity, linear addition is not performed, so that S/N ratio is improved and interference signals are reduced.

FIG. 2 shows the relationship between the input signal (non-video integral signal) and the output signal (video integral signal), taking as an example the case where the number of pulse hits (the number of received pulses) is 4. As can be seen from the figure, according to this method, as the amplitude of the received signal increases, the number of pulse hits increases with a delay with respect to the input signal. Although the increasing number of pulse hits varies depending on the feedback coefficient K, the figure shows a case where the number increases from 4 to 6. FIG. 3 shows this situation on the indicator. In Figure 3, when video integration is off, the azimuth angle a is A with respect to north, but when it is on, it is θ + △θ,
This shows that there is a delay by the difference Δθ. That is, the conventional video integration method has the disadvantage that the direction of the target is delayed by video integration, and the angle of the delay changes depending on the value of the feedback coefficient K. This was a major drawback for the purpose of obtaining the most important azimuth information for radar equipment.

The present invention provides a radar system that solves the above-mentioned drawbacks by correcting the delay in the target direction according to the value of the video integration on/off and the feedback coefficient.

The present invention combines an angle correction circuit using an antenna rotation reference signal and a conventional video integration circuit.
The radar system is characterized in that the azimuth angle of the target is always kept constant by arbitrarily changing the antenna rotation reference signal according to the video integration on/off and the feedback coefficient.

Next, an embodiment of the present invention will be described with reference to FIGS. 4 and 5.

FIG. 4 is a diagram showing the principle of angle correction on the indicator. Let θ be the orientation when video integration is off, that is, the true orientation. There are 3 types of feedback coefficients K
1, K2, and K3, and the angular differences with respect to the true azimuth are Δθ1, Δθ2, and Δθ3, respectively. In order to make these angular differences 0 and always display the target at the position θ, the rotation reference signal of the indicator is changed to a feedback coefficient K.
△θ1, △θ2, △θ3 according to 1, K2, K3
Just delay it.

FIG. 5 shows a block diagram of an embodiment of the present invention. A north mark signal of the antenna 11, which serves as a rotation reference signal for the indicator 17, is generated when the antenna points north. The north mark signal and the rotation signal representing the rotation angle are sent to the angle signal generating circuit 12, where both are synchronized and the north mark is corrected. Correction of the north mark signal is performed by a correction signal Δθ _N generated from the angle reference signal correction circuit 13. The correction signal Δθ _N is controlled by a signal from a video integration selection circuit 14 that turns on/off video integration and selects a feedback coefficient. When video integration is off, △θ _N is 0; when video integration is on and the feedback coefficients are K1, K2, and K3, △θ _N becomes △θ1, △θ2, and △θ3, respectively, and the north mark signal is corrected by △θ _N. . In the figure, 15 is a receiver that receives and processes the received signal from the antenna 11;
16 indicates a video integration circuit.

As described above, the present invention has the effect of correcting deviations in the azimuth angle of a target that occur when performing video integration and obtaining accurate azimuth information by combining an angle correction circuit with a conventional video integration circuit.

[Brief explanation of drawings]

Figure 1 shows the basic block diagram of video integration, and Figure 2 shows the input and output signals, showing how video integration improves the S/N ratio and increases the number of signals that exceed the noise level. Figure 3 shows the signal in Figure 2 observed on the indicator, showing that the azimuth shifts due to on/off operation, and Figure 4 shows the principle of angle correction. ,
FIG. 5 is a block diagram showing an embodiment of the present invention, showing that the target can always be displayed at a constant angle by delaying the sweep reference signal of the indicator. 11...Antenna, 12...Angle signal generation circuit,
13... Angle reference signal correction circuit, 14... Video integration selection circuit, 15... Receiver, 16... Video integration circuit, 17... Indicator.

Claims (1)

[Claims] 1. In a radar system in which a signal obtained by passing a radar reception signal through a video integration circuit having a predetermined feedback coefficient is displayed based on an antenna rotation reference signal, selection means for selecting a feedback coefficient in the video integration circuit. and a correction means for delaying the rotation reference signal by a predetermined angle according to the value of the feedback coefficient in conjunction with the selection by the selection means.