JPH0266485A - Moving target detecting device - Google Patents

Abstract

PURPOSE:To average only a reflection signal from a moving target by extracting only the reflection signal from the moving target from a signal including reflection signal from both the moving target and fixed target and counting up the number of outputs of the reflection signal from the moving target to change the averaging number. CONSTITUTION:When an input signal 1d is passed through an MTI filter 1, a level difference is small as shown in 2d, and at that time the input signal 1d is regarded as a reflection signal from a rain drop and no signal is outputted as shown in 3d. When an input signal ie is passed through the filter 1, an intermediate level difference is generated as shown in 2e, and at that time the input signal 1e is regarded as a reflection signal from a sea surface or the like and no signal is outputted as shown in 3e. When a large level difference is generated as shown in 2f by passing an input signal 1f through the filter 1, the input signal 1f is regarded as a reflection signal from a fixed target such as ground and a mountain and the input signal is outputted as it is. Thus, only the reflection signal from the fixed target can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a moving target detection device for detecting and averaging moving targets in a radar device.

[Conventional technology]

In FIG. 2, 1 is an MTI filter that removes reflected components from fixed objects, 2 is a comparison circuit that compares the output signal of MTI filter 1 with the input signal, and outputs a selection signal to selection circuit 3, and 3 is a comparison circuit. A selection circuit that selects whether or not to output a signal based on the selection signal from circuit 2; 4 is selection circuit 3;
This is an averaging circuit that averages the signals from a predetermined number of signals.

Next, the operation will be explained. An MTI filter 1 removes reflected components from fixed objects from the input video signal. Next, the comparator circuit 2 compares the signal that has passed through the MTr filter with the signal that has not passed through the filter, and based on the rate at which the reflected component has been removed, it regards the signal as a reflected signal from a moving object and outputs the output of the MTI filter 1. mosquito,
Alternatively, it is determined whether or not to output the signal by regarding it as a reflected signal from a fixed object, and a selection signal is output.

The selection circuit 3 selects whether or not to output the output signal of the MTI filter 1 to the averaging circuit 4 based on the selection signal from the comparison circuit 2.

Here, an example will be given and explained. 3 is an input signal, and 2a is a signal passed through the MTI filter 1. In FIG. In this case, since the level difference is small, it is regarded as a reflection from a moving object, for example, raindrops, and the output from the MT■ filter 1 is output to the averaging circuit 4 (3a). In the case of FIG. 4 as well, since the percentage of removed light is small, it is assumed that it is a reflection from a moving object, for example, the sea surface (lb to 3b). In the case of Figure 5, the input signal IC
passes through the MTI filter 1 and is removed as shown in 2C, so it is a fixed object, such as the earth.

Regards it as a reflection from mountains etc. and does not output the signal (3c)
. The averaging circuit 4 averages the signals from the selection circuit 3 by a predetermined number. In this way, signals reflected from raindrops, signals reflected from the sea surface, etc. can be averaged, excluding signals reflected from the ground, mountains, etc.

[Problem to be solved by the invention]

The conventional moving target detection circuit is configured as described above, and since the number of averaging circuits averaged is constant regardless of whether or not the output from the MTI filter is sent to the averaging circuit, There was a problem in that it was not possible to average only the reflected signals.

The present invention was made to solve the problems of the conventional devices as described above, and an object of the present invention is to provide a moving target detection circuit that is capable of averaging only reflected signals from moving objects.

[Means to solve the problem]

The moving target detection device according to the present invention extracts only the reflected signal from the moving target from a signal including the reflected signals from the moving target and the fixed target, and counts the number of output reflected signals from the moving target. By changing the averaging number,
This makes it possible to average only the reflected signals from moving targets.

[Effect]

In this invention, the counting section that counts the number of output reflected signals from the moving target is constituted by a circuit having a counting and memory function, and the number of divisions in the averaging circuit section is changed. It becomes possible to average only the

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a moving target detection device according to an embodiment of the present invention. In the figure, 1 is an MTI filter that removes reflected components from fixed objects, and 2 is an MTI filter that compares the output signal of the MTI filter 1 with the input signal. , a comparison circuit that outputs a selection signal to the selection circuit 3; 3 a selection circuit that selects whether or not to output a signal based on the selection signal from the comparison circuit 2; 4 a selection circuit 3;
An averaging circuit 5 adds up several signals from the comparator circuit and divides it by a number from a counting circuit, which will be described later. This is a counting circuit that outputs a signal that changes the division number.

Next, the operation of this embodiment will be explained. An MTI filter 1 removes reflected components from fixed objects from the input video signal. Next, the comparator circuit 2 compares the signal that has passed through the MTI filter 1 with the signal that has not passed through the filter, and depending on the percentage removed, determines that the signal is a reflected signal from a moving object and outputs the output of the MTI filter 1, or outputs a fixed signal. It determines whether or not to output the signal by regarding it as a reflected signal from an object, and outputs a selection signal.

The selection circuit 3 receives the selection signal from the comparison circuit 2 and selects the MTI
It is selected whether or not to output the output signal of the filter 1 to the averaging circuit 4. The averaging circuit 4 adds the signals from the selection circuit 3 and divides the sum by the signal of the division number from the counting circuit 5.

The counting circuit 5 counts and stores the number of times it is determined to output the selection signal from the comparator circuit 2, that is, the signal after the reflected signal has been removed, and outputs the division number to the dividing section of the averaging circuit 4. With the above operation, only the reflected signals from the moving target can be averaged without error.

For example, if this embodiment device is applied to a weather radar device, the reflected signals from raindrops and It is possible to average signals reflected from the sea surface.

Also, instead of detecting the reflected signal from raindrops by excluding the reflected signal from the earth, mountains, etc., it is possible to detect the reflected signal from the earth, mountains, etc.
It is also possible to detect signals from only a fixed target such as a mountain, and the operation of another embodiment of the present invention will be described below.

When the input signal 1d in FIG. 6 passes through the MTI filter 1, the level difference is small as in 2d, but at this time it is regarded as a reflected signal from raindrops and no signal is output as in 3d. When the input signal 10 in Fig. 7 passes through the MTI filter 1, a moderate level difference occurs as shown in 2e, but in this case it is regarded as a reflected signal from the sea surface, etc., and the signal is output as shown in 38. do not. The input signal of 1f in FIG.
When the input signal passes through the TI filter 1 and a large level difference such as 2f occurs, it is regarded as a reflected signal from a fixed target such as the earth or a mountain, and the input signal is output as is. In this way it is possible to detect only reflected signals from fixed targets.

Yet another embodiment of the invention, shown in Figure 9.10, removes only the reflected signal from the sea surface.

When input signals Ig in FIG. 9, lh in FIG. 10, and 11 in FIG. 11 pass through MTI filter 1, 2 in FIG.
A level difference occurs as shown in g, 2h in FIG. 10, and 21 in FIG. 11. When this level difference is small, it is regarded as a reflected signal from raindrops, and the output of the MTI filter 1 is outputted to the averaging circuit 4 as shown in 3g in FIG. When the level difference is medium, it is regarded as a reflected signal from the sea surface, and no signal is output as shown in 3h in FIG. 10. Further, when the level difference is large, it is regarded as a reflected signal from a fixed target, and the output of the MTI filter 1 is outputted to the averaging circuit 4 as shown at 31 in FIG. In this way, by setting the level difference between whether or not the above-mentioned signal is output to an appropriate value, it is possible to remove only the signal reflected from the sea surface.

〔Effect of the invention〕

As described above, according to the moving target detection device according to the present invention, a circuit for counting and storing selection signals is further added to the moving target detection circuit and the averaging circuit, so that the number of averaging signals can be changed. Therefore, it is possible to average and detect only the reflected signals from the moving target.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing a moving target detection circuit according to an embodiment of the present invention, FIG. 2 is a system diagram showing a conventional moving target detection device, and FIGS. Waveform diagrams for explaining the operation, FIGS. 6, 7, and 8 are waveform diagrams for explaining the operation of other embodiments of the present invention, FIGS. 9, 10,
FIG. 11 is a waveform diagram for explaining the operation of still another embodiment of the present invention. In the figure, l is an MTI filter, 2 is a comparison circuit, 3 is a selection circuit, 4 is an averaging circuit, and 5 is a counting circuit.

Claims (1)

[Claims] 1) A filter that removes a signal reflected from a fixed object from a video signal of a radar device, a comparison circuit that compares a signal that has passed through the filter with a signal that has not passed through the filter, and the comparison circuit. a selection circuit that selects whether to output a signal after the reflected signal has been removed or not to output the signal based on the output of the circuit; an averaging circuit that averages the selected and output signals; A counting circuit that counts the number of times it is determined that the signal after removal is to be outputted and sets the number of times as the averaged number of the above-mentioned averaging circuit, making it possible to average only the reflected signals from the moving object. A moving target detection device.