JPH0440672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic tracking method in a sonar device that clearly and accurately extracts the target signal direction from interference signals and background noise from ships other than the target, and improves the tracking ability.

An automatic tracking system in a conventional sonar device will be explained with reference to FIG. In FIG. 1, reference numeral 1 denotes a receiver array formed by spatially arranging a plurality of receivers (not shown) that convert incoming acoustic waves into electrical signals. Reference numeral 2 denotes a phaser, which phases the outputs of the respective receivers of the receiver array 1 to form a plurality of standby beams, that is, converts them into signals for each of a plurality of directions. 3 is a square-law detection/integrator which performs square-law detection/integration of the output from the phaser 2 for each of a plurality of directions, calculates the power thereof, and uses it as the intensity A for each of a plurality of directions. The intensities A for each of the plurality of directions are obtained by the number of standby beams by the phaser 2, and are as shown in FIG. Reference numeral 4 denotes an interpolation processing circuit, which performs interpolation processing on the intensity A for each of a plurality of directions from the square law detection/integrator 3. The intensity B subjected to this interpolation processing has improved azimuth accuracy as shown in FIG. The maximum (peak) point is determined by the peak detector 5 for the intensity B shown in FIG. 5, and the direction (peak direction) is taken as the target signal direction.

In the case of FIG. 5, A, B, and C are the target signal directions. In other words, target signal azimuth D, which is being interfered with by target signal azimuth C, does not produce a maximum point and therefore cannot be tracked, and the peak azimuth of target signal azimuth A, which is a weak signal, is greatly affected by even a small amount of noise. The disadvantage was that it fluctuated and became impossible to track.

In view of the above-mentioned drawbacks of the conventional devices, the present invention enables tracking in areas where the intensity changes convexly in each direction, and also clearly detects the target signal even with weak signals superimposed on noise. This paper aims to provide an automatic tracking method for sonar that can extract the direction and perform stable direction tracking. Intensity X _N for each direction N obtained by phasing the output, square-law detection and integration
Then, using the intensities X _N-1 and X _N+1 of adjacent directions, the target signal enhancement process is performed as follows: C _N = X _N - (X _N-1 + X _N+1 )/2. After calculating the intensity C _N for each N, interpolation processing is performed, and then,
This automatic tracking method for sonar is characterized by detecting a peak point and tracking that direction as a target signal direction. The present invention will be explained in detail below.

FIG. 2 shows an embodiment of the present invention, in which:
Components that are the same as those in FIG. 1 showing the conventional example are represented by the same reference numerals. That is, 1 is a receiver array, 2 is a phaser, 3 is a square law detection/integrator, 4 is an interpolation processing circuit,
5 is a peak detector. Reference numeral 6 denotes a target signal enhancement processing circuit, which is a feature of the present invention, and is inserted between the square law detection/integrator 3 and the interpolation processing circuit 4.

In the above configuration, as described above, the output of the receiver array 1 passes through the phaser 2 and the square law detector/integrator 3, and becomes the intensity A for each of a plurality of directions as shown in FIG. In the method of the present invention, the target signal enhancement processing circuit 6 performs target signal enhancement processing, which will be described later, on the intensity A for each of the plurality of directions, and then the intensity C for each of the plurality of directions subjected to the target signal enhancement processing.
is sent to the interpolation processing circuit 4 and subjected to interpolation processing to obtain more detailed intensity D for each direction.

Here, the target signal _enhancement processing is to calculate _{C N =} X _N − (X _{N- 1} +X _N+1 )/2 ...(1) The intensity C _N for each direction N is calculated by performing the following calculation process:
This is a linear filter process that searches for .

Figure 6 shows the intensities C for each of a plurality of directions obtained by applying this target signal enhancement processing to the intensities A for each of a plurality of directions, and the interpolation The processed intensity D for each direction is shown in FIG. 7.

In the intensity D for each finer direction obtained in this way, a local maximum point also occurs for the target signal direction D. Therefore, if the intensity D for each finer direction is inputted to the peak detector 5, The peak detector 5 can detect any of the target signal directions A, B, C, and D, making it possible to track the target signal.

By the way, in general, the interpolated output Z of the input sequence {y _i }
is the linear filter output expressed by the formula Z=〓α _i y _y …(2) (where α _i is a constant), so the interpolation process and target signal enhancement process are superimposed,
This can be achieved with just one stage of linear filter processing.

This embodiment is shown in FIG. 3. By inputting the intensities A for each of a plurality of directions into the (target signal emphasis + interpolation) processing circuit 7, the intensities D for each more detailed direction are immediately obtained. Obtainable. Such a (target signal enhancement+interpolation) processing circuit 7 can be easily realized by a combination of known circuits, and the configuration is simplified compared to the embodiment shown in FIG.

Note that, as shown in equation (1), the target signal enhancement process corresponds to creating a second-order difference sequence of the input data sequence, and the degree of inflection (convex or concave, or its extent).

A test was conducted using an actual sonar device to determine whether the peak azimuth obtained in this manner coincided with the actual target signal azimuth, and it was confirmed that they matched with sufficient accuracy for practical use.

As explained above, according to the present invention, in a sonar device that automatically tracks a target signal direction, the outputs of a plurality of receivers are phased, and the intensities for each direction obtained by square-law detection and integration are , performs interpolation processing after performing a predetermined target signal enhancement process, then detects the peak point, and tracks that direction as the target signal direction, so parts where the intensity changes convexly in each direction can be clearly seen. It also has the advantage of being able to capture and track with high precision, and to continue highly stable tracking even when affected by interference from other ships or background noise.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and FIG. 1 is a block diagram of a conventional sonar automatic tracking system, FIG. 2 is a block diagram of a sonar automatic tracking system showing an embodiment of the present invention, and FIG. 3 is a diagram of a sonar automatic tracking system. A configuration diagram of an automatic tracking system for sonar showing another embodiment of the present invention, FIG. 4 is an explanatory diagram of the output of the square law detection/integrator, and FIG. 5 is an explanatory diagram of the output of the interpolation processing circuit in the conventional system. FIG. 6 is an explanatory diagram of the output of the target signal processing circuit in the method of the present invention, and FIG. 7 is an explanatory diagram of the output of the interpolation processing circuit in the method of the present invention. DESCRIPTION OF SYMBOLS 1... Receiver array, 2... Phaser, 3... Square detector/integrator, 4... Interpolation processing circuit, 5... Peak detector, 6... Target signal enhancement processing circuit, 7...
(Target signal enhancement + interpolation) processing circuit.

Claims (1)

[Claims] 1. In a sonar device that automatically tracks a target signal direction, the outputs of a plurality of receivers are phased, and the intensity X _N for each of a plurality of directions N obtained by square-law detection and integration is , using the intensities X _N-1 and X _N+1 of adjacent directions, performs target signal enhancement processing of C _N = X _N - (X _N-1 + X _N+1 )/2 for each of multiple directions N. After finding the strength C _N , perform interpolation processing, and then
An automatic tracking method for sonar that detects the peak point and tracks that direction as the target signal direction.