RU1840753C - Echo-ranging sonar with complex-shaped sound impulses - Google Patents

Abstract

FIELD: radio-engineering.

SUBSTANCE: invention refers to radio-engineering, and namely to hydroacoustic equipment, and can be used when designing hydroacoustic equipment of naval forces objects. Echo-ranging sonar consists of acoustic antenna, transmission path with master generator and sound impulse modulator, control instruments connected to modulator input, and receiving path with processing device of received modulated signals. Path of single-sideband modulation of underwater communication system is used as modulator.

EFFECT: improving efficiency of echoscopy of targets by using complex-shaped sound impulses.

1 dwg

Description

The invention relates to sonar technology and can be used in the development of sonar weapons of naval facilities.

At present, to detect targets with a low speed relative to the observer, when the main obstacle is the reverberation noise (inefficiency of "Doppler" filters for small relative target speeds), sonars with sounding signals of complex shape are being developed. The use of such sounding signals, as is known, significantly increases the noise immunity of the sonar with respect to reverberation noise, due to a significant narrowing of the autocorrelation function of the signal and, accordingly, a decrease in output fluctuations due to the heterogeneity of the scatterers. A sonar with complex pseudo-noise signals is described in the articles by Westerfield, Prager, Stuart “Winning with respect to the signal / reverberation using matched filters” and Allen, Westerfield “Digital correlators with time compression and matched filters for active sonar” (Foreign electronics No. 1, 1961 and No. 12, 1964, respectively).

However, devices for the formation and optimal processing of complex signals are very complex and have large dimensions. This does not allow, in particular, to introduce the radiation mode of complex signals into previously developed sonars with tone-pulse sounding signals, in order to increase their efficiency when detecting targets with small radial components of relative speed. The desirability of improving these sonars is nevertheless obvious, since they are widespread and are installed as part of sonar systems on submarines and surface ships of the Navy.

The aim of the present invention is the introduction into the sonar mode of emission of complex signals without the use of complex and bulky devices for the formation and processing of these signals.

The essence of the proposal is to use short speech signals (words, numbers or short phrases) or other specific signals (foreign words, sounds of biological origin, etc.) as sounding pulses, and as a receiving analyzing device that is well matched with such signals, human hearing aid operator. At the same time, there is great freedom in choosing the type of complex signal, which is a definite tactical advantage, since it allows masking of its own radiation.

Increasing the sonar efficiency with a small Doppler target in the case of auditory processing of speech signals used as sounding pulses is based on the following premises and considerations:

1. The above about smoothing the reverberation of complex signals refers to a speech signal, which is their special case.

2. Hearing is a very perfect tool for identifying sound images, which is explained by the cross-correlation nature of the mechanism for identifying a given sound sample in the human brain with one of the images stored in his memory (F. Lange, “Correlation Electronics”, Sudpromgiz, L., 1965 .).

So, for example, according to the literature (J. Flanagan, “Analysis and Perception of Speech”, Svyaz Publishing House, Moscow, 1968) 90% intelligibility of digital material is provided at a signal / noise ratio of 9 dB. Obviously, the noise immunity of the detection of a single speech signal, when used as a probe pulse, should be no worse than the specified value. Naturally, for this purpose, one should choose signals that are well recognized by the human hearing aid.

Description of the sonar station.

The drawing shows a block diagram of a sonar station with complex waveforms such as speech.

1 - acoustic antenna;

2 - antenna switch;

3 - amplifier device;

4 - generator device;

5 - a device for generating a signal when radiation is a single-band telephone modulator,

6 - heterodyne amplifier;

7 - master oscillator - local oscillator;

8 - recording device.

When a probe pulse is emitted, a voltage pulse of complex shape corresponding to the voice message delivered by the operator to the microphone or a special signal played by the sound recorder (8) is supplied to the single-band telephone modulator (5). Using a modulator, the spectrum of the original signal is transferred to the operating frequency band of the sonar. The signal at the output of the modulator serves as the excitation voltage of a powerful generator device (4), the output of which is supplied to the acoustic antenna (1) through the antenna switch (2). In the mode of receiving echo signals, the voltage that arises at the output of the acoustic antenna through the antenna switch is supplied to an amplifying device (3) and then to a local oscillator amplifier (6), designed to invert the conversion of echo signals into the speech frequency range before applying it to the loudspeaker, or Phones The analysis of the received signals is carried out by ear by the operator serving the station. When an echo is detected, the operator stops the distance counter launched by him at the time of the emission of the probe pulse.

It should be noted that under the conditions of Doppler distortion, the spectrum of the echo signal differs from the original one, nevertheless, the high efficiency of the auditory reception method remains at sufficiently large Doppler shifts. (According to the literature, when receiving single-band signals of commercial telephony, inaccuracies in restoring the carrier frequency to 50 Hz are allowed. In this case, only the timbral characteristics of the signal are changed, and not its intelligibility).

The total dimensions of the forming and receiving devices of the speech signal do not exceed one block, which allows to implement the radiation mode of complex signals in existing sonars by using special consoles.

In particular, telephone communication modes of hydroacoustic complexes can be directly used, in accordance with this proposal, for the location of closely located objects. This was checked in November 1967 in the process of state testing of a sonar system. Using the near telephony link of this complex, the submarine 675 of the project was repeatedly unmistakably located, sailing in a parallel course at a distance of 4 miles.

Claims (1)

A sonar station containing an acoustic antenna, a transmission path with a master oscillator and a modulator for generating probe pulses, control devices connected to the input of the modulator, and a receive path with a device for processing received modulated signals, characterized in that, in order to increase the efficiency of target echo location by the use of probe pulses of complex shape, in it as a modulator the path of single-band modulation of the underwater communication station is used.