KR19990054185A - Automatic gain control signal transmission circuit structure of sound detector - Google Patents

Abstract

The present invention relates to an automatic gain control (AGC) signal transmission circuit unit in a ship of a sound detector, and more particularly, to a circuit structure for controlling a transmission gain ratio in an acoustic sensor unit for multiplexing and transmitting underwater sound. will be.

The present invention provides a buffer amplifier for receiving each bit of a 3-bit automatic gain control (AGC) signal provided in parallel; A transistor for supplying an on / off output from the buffer amplifier to its emitter to perform a switching operation; A resistor connected between a power supply line and an emitter of the transistor to limit an operating current of the transistor; And a transmission line for transmitting a signal as a current loop as the transistor is turned on, and achieves a technical effect of stably transmitting a desired signal without being affected by a voltage drop caused by a long distance transmission. do.

Description

Automatic gain control signal transmission circuit structure of sound detector

The present invention relates to an automatic gain control (AGC) signal transmission circuit unit in a ship of a sound detector, and more particularly, to a circuit structure for controlling a transmission gain ratio in an acoustic sensor unit for multiplexing and transmitting underwater sound. will be.

In general, in the sound detector for detecting an acoustic signal in the water to detect the exact position of the sound source, the method of detecting the sound wave in the water is an active sonar that emits sound energy and receives the reflected sound energy from the object. There is a (Sonar) method and a passive sonar method that receives only acoustic energy radiated from other sound sources.

1 is a block circuit diagram schematically showing a general sound detector. The sound detector system includes: an acoustic sensor unit 10 for detecting an underwater sound signal, converting it into an electrical analog signal, converting the sound signal into a digital signal, and multiplexing and transmitting the same; A towing cable 30 for connecting the acoustic sensor unit 10 to the ship 40; It is configured to include a ship (40) connected to the acoustic sensor unit 10 by the towing cable (30).

In addition, the ship 40 is classified into a data receiver 42 for processing a mux signal transmitted from the acoustic sensor unit 10, and the electrical signal data received from the data receiver 42, the sound by It is composed of a data processor 44 for restoring a signal, and comprises a control signal and a power supply 46 for controlling and supplying power to the acoustic sensor unit 10.

Sound generated in the water is propagated to the surroundings by the mechanical tight action of seawater particles. The acoustic vibration reaches the hydrophone 12 in a magnitude proportional to the product of the square of the frequency and the amplitude, causing the volume change, and the hydrophone 12 responds to the volume change in response to an electric wave that is homogeneous with the sound wave. Generates the corresponding electrical signal. The electrical signal is input to the mux unit 16 via a differential amplifier 14 for noise reduction.

The signal input to the mux unit 16 is sequentially multiplexed, and then digitally signaled through a sampling and quantization process, and then transmitted to the ship 40 through a towing cable 30 through a vibration isolation module (not shown). . In this case, the transmission signal may be expressed in the form of a change in current or a change in voltage. However, since the towing cable 30 is a long distance of several kilometers, it is generally converted into a current form and transmitted.

However, the signal sensed by the hydrophone and applied to the mux of the signal transmission module via the preamplifier is not only low in output level, but also a long distance from the preamplifier to the mux is 120 m. The incoming noise is directly input to the mux, and the gain controller at the rear end of the mux has a problem that the gain is not properly processed because the gain is controlled while the noise level is raised.

The present invention has been made to solve the above problems, an object of the present invention is to transmit the sound signal detected in the hydrophone, by adjusting the amplification degree in the acoustic sensor according to the strength of the signal level received from the ship The present invention provides a circuit for transmitting an automatic gain control (AGC) signal transmitted by a ship to enable transmission.

1 is a block circuit diagram schematically showing a circuit configuration of a general sound detector;

2 is a block circuit diagram of a master logic circuit as an example to which the present invention is applied;

3 is a block circuit diagram of a slave logic circuit to which the present invention is applied;

4 is a circuit diagram showing a circuit configuration of an automatic gain control (AGC) signal transmission circuit constructed in accordance with the present invention.

※ Explanation of code about main part of drawing ※

10; Acoustic sensor unit 30; Towing cable

40; Shipboard 42; Data receiver

Q1; Transistor D1; diode

410; Buffer amplifier

In order to achieve the above object, the present invention provides a buffer amplifier for receiving each bit for a 3-bit automatic gain control (AGC) signal provided in parallel; A transistor for supplying an on / off output from the buffer amplifier to its emitter to perform a switching operation; A resistor connected between a power supply line and an emitter of the transistor to limit an operating current of the transistor; And a transmission line for transmitting a signal as a current loop as the transistor is turned on, to provide an automatic gain control signal transmission circuit structure for a sound detector.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block circuit diagram of a master logic circuit as an example to which the present invention is applied, and FIG. 3 is a block circuit diagram of a slave logic circuit to which the present invention is applied.

The master logic circuit, together with the slave logic circuitry, functions as the digital signal control logic of the sound detector. For detailed operation of the master logic circuit and the slave logic circuit, see the applicant's patent application "Master logic circuit for AGC transmission and reception of sound detector" and "Slave logic circuit for group synchronization and A / D conversion of sound detector". It is explained in detail.

As a main function of the master logic circuit, first, an automatic gain control (AGC) signal reception and processing function thereof will be described.

The automatic gain control (AGC) signal transmitted from the ship 40 is a 3-bit parallel transmission method, and has a voltage level of ± 15V, and this transmission code is transmitted in a 3-bit gray code. In the case of using such a transmission line of AWG 24, the line resistance is about 80 mW / km, so the total resistance is 80 mW / km × 2 km = 160 mW.

In this case, when the transmission voltage is set to 10V, the change in applicability according to the change of each bit value of the automatic gain control (AGC) signal is about 8 kV as the minimum and about 22 kV as the maximum. On the other hand, since the current transfer ratio CTR of the optocoupler 510 is at least 50%, the output current is at least 4 mA. Therefore, the resistance value of the pull-up resistor RA1 is 5V / 4㎃ = 1.25㏀ or more when the optocoupler 510 is completely turned on when a voltage of + 5V is applied to the pull-up resistor RA1. Sensitive to noise Therefore, the resistance value of the pull-up resistor RA1 is preferably selected to 2 kΩ.

On the other hand, series resistors R4, ..., R9 of the transceiver circuit limit excessive current and serve as RC filters. If the AGC data is 0, it is transmitted at -10V. At this time, no current flows through the optocoupler 510, but current flows through the diodes D1, D2, and D3. If the current transfer ratio of the optocoupler is large, the noise margin is very small, so a reverse voltage is applied so that the + voltage is not applied even if the noise is induced. At this time, the allowable reverse voltage of the optocoupler is as small as about 6V to prevent the excessive reverse voltage applied to the diode (D1, D2, D3).

Automatic gain control (AGC) data transmitted on board is converted to gray code to minimize 1-bit error. The master logic circuit receives this, converts it into general binary code, and outputs it to the slave logic.

The master logic circuit transmits the serial data using one wire to transfer the AGC data to the slave logic. This serial data is transmitted every frame in the order of "0, AGC2, AGC1, AGC0". Parallel auto gain control (AGC) data from the ship is read every time the frame starts, so there is a maximum delay of up to two frames until the ship AGC signal changes and the AGC output changes in the slave logic.

On the other hand, the distance from the master logic to the sub-mux is up to 200m, which is quite far, so we use the RS-422 driver, which is a differential transmission method. The twisted pair wire of the differential transmission method is not only resistant to noise but also generates a small amount of noise. In addition, since the capacitance of the cable is small, the transmission speed is also an advantage.

3 is a circuit diagram showing a circuit structure of an automatic gain control (AGC) transmission circuit according to the present invention.

This circuit is a system for transmitting data in a single direction from a transmitter to a receiver, and is a circuit structure used for long distance transmission, high data rate, and low current source level.

In order to improve data transmission performance, the transmitter is configured in a non-isolated state, and the receiver is configured in an isolated state.

In ships, automatic gain control (AGC) signals are composed of three bits and transmitted to the acoustic sensor. These three-bit signals are arranged in parallel and input to respective terminals indicated by reference numerals A, B, and C. This automatic gain control (AGC) signal is input to the buffer amplifier 410.

The buffer amplifier 410 is to prevent the input terminal from being affected by the on / off operation of the transistor Q1 of the output terminal. The output of this buffer amplifier 410 is supplied to the emitter of transistor Q1 via resistor R2.

On the other hand, a resistor R1 for limiting the current in the on operation of the transistor Q1 is connected between the power supply line Vcc and the emitter of the transistor Q1.

When the transistor Q1 is turned on according to an automatic gain control (AGC) signal transmitted from a ship, current between the emitter collectors of the transistor is transmitted by a current loop configured up to the acoustic sensor unit. Receive the signal through the optocoupler.

Here, the operation state of the transistor Q1 can be checked visually through the light emitting diode D1 connected in a forward direction between the power supply Vcc and its base. In addition, a surge voltage absorbing capacitor C1 is connected between the base and the ground of the transistor Q1 to stabilize the operation of the transistor Q1.

On the other hand, when the current source is located at the transmitting end, the current loop is charged to about 2.5V, and the data transfer rate is fast. On the other hand, when the current source is located at the receiving end, the current loop is charged up to the applied voltage to slow down the data transmission rate.

Therefore, the circuit of the present invention places the current source at the transmitting end so that the data transfer rate is not affected by the applied voltage of the current source.

The current source is controlled on / off using a buffer amplifier at the receiving end to achieve high output impedance. In this case, a current loop of 20 mA is generated.

On the other hand, if a current loop of about 2km is configured, an applied voltage of about 12V is required for the current source.

The data transfer rate is not affected by the applied voltage as described above, but only by the length of the loop. Signal transmission distortion is also caused by the interval between the output bits and the interval between the input bits.

As described above, the present invention provides a current conversion type transmission circuit which can automatically adjust the gain of the transmission amplifier stage according to the magnitude of the signal transmitted from the underwater acoustic detector, thereby avoiding the voltage drop caused by the long distance transmission. The technical effect of stably transmitting a desired signal can be achieved.

While the invention has been shown and described with respect to certain preferred embodiments, it will be appreciated that the invention can be modified and modified in various ways without departing from the spirit or scope of the invention as set forth in the claims below. Those skilled in the art will readily know.

Claims (1)

A buffer amplifier 410 that receives each bit with respect to a 3-bit automatic gain control (AGC) signal provided in parallel; A transistor (Q1) for supplying an on / off output from the buffer amplifier (410) to its emitter to perform a switching operation; A resistor (R1) connected between a power supply line and an emitter of the transistor (Q1) to limit the operating current of the transistor (Q1); And, And a transmission line for transmitting a signal as a current loop as the transistor (Q1) is turned on.