KR0175784B1 - Passive Preamplifier for Noise Reduction of Piston Line Array Acoustic Detector - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preamplifier for an acoustic module provided in an acoustic sensor unit of an acoustic detector (Towed Array Sonar Syatem) for detecting an accurate location of a sound source And the hydrophone of the acoustic detector connected by the towing cable from the ship is converted into the electric signal and applied to the preamplifier. In this case, the low-noise amplification unit constituting the preamplifier firstly amplifies and then the low-frequency band is amplified by the seawater noise compensation amplification unit, and the high-frequency band is amplified and applied to the low-pass filter. The low-pass filter low-pass filters an input signal and performs gain control by a gain controller to satisfy a gain. Then, the low-pass filter transforms a signal from an analog signal to a digital signal using an analog / digital converter, There is an effect that the distortion or the distortion of the generated signal can be immediately restored.

Description

Passive Preamplifier for Noise Reduction of Piston Line Array Acoustic Detector

[0001] The present invention relates to an acoustic detector, and more particularly to an acoustic sensor of a towed array Sonar Syatem for detecting the exact position of an acoustic source (type of a sound source, moving speed of a sound source) The present invention relates to a preamplifier for a sound module.

In general, a method in which an acoustic detector that detects an acoustic signal in the water and detects an accurate position of an acoustic source senses an underwater acoustic wave is an active sonar method in which acoustic energy is radiated and the acoustic energy is reflected from the object And a passive sonar system that receives only acoustic energy emitted from other sources.

FIG. 1 is a block circuit diagram schematically showing a general acoustic detector. FIG. 1 is a block diagram of a general acoustic detector, which includes a sound sensor unit 300 for detecting an acoustic signal in water and converting it into an electrical analog signal, A towing cable 200 connected to the acoustic sensor unit 300; A signal processing unit 120 connected to the towing cable 200 and transmitting an electric signal received from the sound sensor unit 300; a data processing unit 120 for classifying, searching, and processing the electric signal data received from the signal processing unit 120 (110). ≪ IMAGE >

The acoustic sensor unit 300 includes a vibration isolation module 300 for attenuating initial vibration, a signal transmission module 320 for converting an input analog signal into a digital signal and transmitting the digital signal, And a tail rope assembly 340 for attenuating the vibration finally.

As shown in FIG. 2, the acoustic module 330 of the acoustic sensor unit 300 receives an acoustic signal in the water and converts it into an electrical signal, and removes seawater noise flowing through the signal (Hydrophone) 331 for receiving an acoustic signal of the seabed and converting it into an electric signal, a preamplifier 332 for amplifying a fine signal, and a preamplifier 332 from an overcurrent A roll sensor 335 for detecting tilting of the sound sensor unit 300 and a sea noise correction circuit 335 for compensating noise caused by the sea water, A water level sensor 337 for measuring the water depth of the sound sensor unit 300, an orientation sensor 338 for measuring the direction of the sound sensor unit 300, And a test controller 336 which tests the test data.

Hereinafter, the operation of the acoustic sensor unit 300 will be described in detail.

The underwater sound is propagated by the mechanical close action of the seawater particles and this vibration causes a change in the volume of the water hammer 331 to a magnitude that is directly proportional to the product of the square of the frequency and the amplitude, And generates an electrical energy signal corresponding to the electric waveform rate equivalent to the sound wave.

The electrical energy signal is expressed in the form of current and voltage. When the impedance matching is performed in consideration of the sensitivity of the hydrophone 331 with the output stage preamplifier 332, the signal of the hydrophone 331 can be transmitted away.

The signal thus processed passes through the seawater noise compensating circuit 334, and the noise signal in the seawater existing in the low frequency region is cut off, and the attenuated high frequency component signal is compensated and transmitted to the signal transmitting module 320.

The depth sensor 337 and the orientation sensor 338 of the acoustic module 330 respectively measure the orientation and depth information of the acoustic sensor unit 300 and transmit the measurement to the signal transmission module 320.

The signals transmitted to the signal transmission module 320 through the above process are sequentially multiplexed and then subjected to a sampling and quantization process to be digitized and transmitted to the ship 100 via the vibration isolation module 310.

The preamplifier 332 constituting the acoustic sensor unit 300 of the acoustic detector having the above functions amplifies the weak signal at the output stage of the hydrophone 331 and amplifies the weak signal at the output stage of the hydrophone 331, And easily amplifies a small signal of the hydrophone 331 after the emphasis processing for signal processing.

Since the minute noise introduced from the hydrophone 331 is also amplified by the signal when the signal is amplified by the preamplifier 332, the amplification factor of the preamplifier 332 By limiting the amplification circuit bandwidth, noise levels are being reduced.

3 is a block circuit diagram schematically showing the configuration of a conventional preamplifier. The preamplifier 332 includes a low-noise amplifier 332a for amplifying a low-noise signal applied from the hydrophone 331, A seawater noise compensating amplifying unit 332b for intercepting the applied seawater noise and compensating only the high frequency signal and outputting the signal; a low-pass filter connected to the seawater noise compensating amplifying unit 332b for passing only the low- And a current driver 332d connected to the low-pass filter 332c for outputting an applied signal in a current form in order to prevent a signal attenuation phenomenon occurring in long-distance transmission.

In the conventional manual passive acoustic sensor, when a fine signal corresponding to a sound signal is applied from the hydrophone 331, the acoustic signal is amplified and applied to the seawater noise compensation amplifier 332b. The seawater noise compensation amplifying unit 332b cuts off the seawater noise existing in the low frequency region, and then compensates only the high frequency signal and outputs it to the low pass filter 332c. When a signal is applied to the low-pass filter 332c from the seawater-noise-compensated amplifier 332b, the low-pass filter 332c passes only the low-frequency portion to prevent the occurrence of a frequency aliasing phenomenon, . The current driver 332d converts the signal into a current signal to output a signal to the analog multiplexer 320a of the signal transmission module 320 to prevent a signal attenuation phenomenon occurring when the applied signal is transmitted over a long distance .

However, since the signal sensed by the hydrophone 331 is very small and the output level is low, there is a problem that the influence of the noise introduced from the surrounding circuit is greatly affected. Particularly, since the length of the transmission line for transmitting the signal is long, There was a problem in functioning.

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a sound module, which comprises an acoustic detector, in which a signal applied from a hydrophone to a preamplifier is distorted or distorted To restore the original state to the original state.

FIG. 1 is a block circuit diagram schematically illustrating a general acoustic detector. FIG.

FIG. 2 is a block diagram showing in detail the acoustic module and the vibration isolation module constituting the acoustic detector of FIG. 1;

FIG. 3 is a block circuit diagram schematically showing a configuration of a conventional preamplifier; FIG.

4a is a block circuit diagram schematically showing a passive-type acoustic detector according to the present invention, and FIG. 4b is a block circuit diagram schematically showing a preamplifier of an acoustic module according to the present invention.

DESCRIPTION OF THE REFERENCE NUMERALS

500: sound module 510: hydrophone

520: Preamplifier 521: Low noise amplifier

523: Seawater noise compensation amplifying unit 525: Low frequency filter

527: Gain Controller 529: Analog / Digital Converter

600: signal transmission module 610: digital mux

700: Vibration isolation module 800:

850: Towing cable 900: Acoustic sensor part

In order to achieve the above object, the present invention provides a vibration isolation module comprising: a vibration isolating module connected to a cabin through a tow cable and attenuating initial vibration; A signal transmission module for converting an input analog signal into a digital signal and transmitting the digital signal; A sound sensor unit comprising a hydrophone unit, a preamplifier, a roll sensor, a protection circuit, a seawater noise compensation circuit, a water depth sensor, an orientation sensor, and a test controller to detect a sound signal, A preamplifier configured to amplify a low noise signal applied from a hydrophone; a seawater noise compensation amplifying unit connected to the low noise amplifying unit to block seawater noise applied to the low noise amplifying unit to compensate for only a high frequency signal, A gain controller connected to the noise compensation amplifier and connected to the low pass filter for gain control of a signal applied from the low pass filter; a gain controller connected to the gain controller and connected to the low pass filter, To an analog / digital converter . ≪ / RTI >

The signal transmission module may include a digital MUX.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings.

4a is a block circuit diagram schematically showing a passive-type acoustic detector according to the present invention, and FIG. 4b is a block circuit diagram schematically showing a preamplifier of an acoustic module according to the present invention.

Referring to FIG. 4A, an acoustic sensor unit 900 detects an acoustic signal in the water, converts the acoustic signal into an electrical analog signal, converts the analog signal into a digital signal, multiplexes the digital signal, and transmits the digital signal. A towing cable 850 connected to the acoustic sensor unit 900; And a data processing unit connected to the towing cable 850 and configured to classify, search, and process the electrical signal data received from the signal processing unit, a signal processor 800 for transmitting electrical signals received from the acoustic sensor unit 900, .

The acoustic sensor unit 900 includes a vibration isolation module 700 for attenuating initial vibration, a signal transmission module 600 for converting an input analog signal into a digital signal and transmitting the analog signal, and a sound module 500). The acoustic module 500 receives the acoustic signal from the water and converts it into an electrical signal, and removes seawater noise flowing through the signal. The module 500 receives the acoustic signal of the seabed and converts the acoustic signal into an electric signal 510 A preamplifier 520 for amplifying a fine signal, and the like.

Referring to FIG. 4B, a fine signal corresponding to the acoustic signal sensed by the hydrophone 510 constituting the acoustic module 500 is applied to the preamplifier 520. The signal applied from the hydrophone 510 to the preamplifier 520 is applied to a low noise amplification unit (LAN) 521 constituting the preamplifier 520. The low-noise amplifier 521 first amplifies the applied fine signal to about 35 dB using a low-noise high input impedance. The signal amplified by the low-noise amplifier 521 is applied to a seawater noise compensation amplifier (SNCA) 523. At this time, there exists seawater noise existing in the low frequency region in the signal applied to the sea water noise compensation amplifying unit 523. The seawater noise compensation amplifying unit 523 is composed of a high-pass filter (HPF) to block and remove seawater noise existing in a low-frequency region, and then compensates and outputs only a high-frequency signal.

(1 / f) noise occurs in the low-pass band, and the Johnson noise and the shot noise are generated in the frequency modulation band or more. In this case, And is distributed uniformly in the frequency band, it is called white noise

The signal output from the seawater noise compensation amplifying unit 523 is applied to a low-pass filter (LPF) In order to prevent a frequency aliasing phenomenon occurring when the analog signal is sampled before being converted into a digital signal, the low-pass filter 525 has a corner frequency of 1.6 kHz and an excellent blocking characteristic of 4 . Accordingly, the low-pass filter 525 passes only the low-frequency portion of the applied signal. The signal filtered in the low-pass filter 525 is applied to a connected gain controller 527. The gain controller 527 is configured to control the gain controller 527 to 4 bits using a logarithmic DAC so as to be adjustable in 3 dB steps according to the level of an applied signal. The signal applied to the gain controller 527 is gain-controlled and applied to the analog / digital converter 529.

The analog / digital converter 529 converts the applied analog signal into a digital signal. At this time, when an analog signal is converted into a digital signal, it is controlled and converted by an applied clock signal and a conversion signal. The converted signal from the analog / digital converter 529 is applied to the digital mux 610 of the signal transmission module 600 and then transmitted to the shipboard 800.

As can be seen from the above description, the hydrophone of the acoustic detector connected by the towing cable from the shipboard converts the sensed acoustic signal into an electric signal and applies it to the preamplifier. In this case, the low-noise amplification unit constituting the preamplifier firstly amplifies and then the low-frequency band is amplified by the seawater noise compensation amplification unit, and the high-frequency band is amplified and applied to the low-pass filter. The low-pass filter low-pass filters an input signal and performs gain control by a gain controller to satisfy a gain. Then, the low-pass filter transforms a signal from an analog signal to a digital signal using an analog / digital converter, There is an effect that the distortion or the distortion of the generated signal can be immediately restored.

While the present invention has been particularly shown and described with reference to the exemplary embodiments thereof, the present invention is not limited thereto and various changes and modifications may be made without departing from the scope of the present invention.

Claims (7)

A vibration isolation module connected to the shipboard via a tow cable and attenuating the initial vibration; A signal transmission module for converting an input analog signal into a digital signal and transmitting the digital signal; A sound sensor unit comprising a hydrophone unit, a preamplifier, a roll sensor, a protection circuit, a seawater noise compensation circuit, a water depth sensor, an orientation sensor, and a test controller to detect a sound signal, A preamplifier configured to amplify a low noise signal applied from a hydrophone; a seawater noise compensation amplifying unit connected to the low noise amplifying unit to block seawater noise applied to the low noise amplifying unit to compensate for only a high frequency signal, A gain controller connected to the noise compensation amplifier and connected to the low pass filter for gain control of a signal applied from the low pass filter; a gain controller connected to the gain controller and connected to the low pass filter, To an analog / digital converter Wherein the preamplifier is configured to amplify the noise of the passive matrix pre-array acoustic transducer. The preamplifier of claim 1, wherein the low-noise amplifier amplifies the applied fine signal to 35 dB. 2. The preamplifier of claim 1, wherein the seawater noise compensation amplifier comprises a high pass filter (HPF) for compensating the seawater transmission characteristics of the sound waves. The noise cancellation preamplifier of claim 1, wherein the low-pass filter comprises four stages. 2. The preamplifier of claim 1, wherein the gain controller is adjusted in three stages from 0 to 45 dB according to the applied signal level. The noise cancellation preamplifier of claim 1, wherein the gain controller is controlled to 4 bits by a logarithmic DAC. The preamplifier of claim 1, wherein the analog / digital converter is controlled by a clock signal and a convolution signal.