SU1138774A1 - Device for marine geophysical explorations - Google Patents

Abstract

1. DEVICE OF THE DAY OF SEA GEOPHYSICAL RESEARCH, containing in the towed part a receiving acoustic transducer, analog-to-digital converter and a shift register connected in series, radiating acoustic transducer and code transmission line, and in the side part - marker separation circuit, synchronizer, receiving shift register, recorder and impulse current generator, characterized in that, in order to simplify the device and increase its noise immunity, a gene is introduced into its towed part pulse generator, first control circuit, marker shaper, bipolar code driver and first one, matching circuit, and onboard part - the second matching circuit, code converter and second control circuit, the output of the pulse generator is connected to the input of the first control circuit, the first the output of which is connected to the control input of the analog-digital converter, and the second output - to the control inputs of the shift register and marker generator, the signal input of the latter is connected to the output of the shift register and s The input of the bipolar code former, the control input of which is connected to the output of the marker former, and the output to the input of the first matching circuit, the output of which is connected to the signal inputs of the code converter and the marker output circuit through the code transmission line and the second the synchronizer is connected to the input of the second control circuit, the first output of which is connected via an impulse current generator to the input of (L a luminous acoustic transducer, and the second output - with a control conductive inputs of the recorder, the receiver shift register, the token assignment scheme and the code converter, the output of the last shift register receiving through 00 is connected to the signal input of device B zapieo m. 2. The device according to claim 1, differing in that in the towing part, additional (p- |) receiving acoustic transducers, analog-to-digital transducers and shift registers are added, connected in series, where G) 2, 3, 4, in addition , all the n shift registers are connected in series between the nd outputs and the second signal inputs, and the shaper of the first channel marker, the output of which is connected to the second control input of the shaper of the bipolar code, the signal

Description

the input to the output of the shift register, and the control input to the output of the first control cxeNBJ and the control inputs of the input (n-1 / analog-to-digital converters and shift registers) (channel counter, auxiliary generator, channel control circuit i. a circuit for switching off channels, a circuit for marking the marker of the first channel, the signal input of the latter being connected to the output of the second circuit co. 8774

and output through the first input of the control circuit of the channel, the circuit of the channel and the channel counter connected to the second control input of the recorder and to its control input, the second input of the channel control circuit is connected to the synchronizer code and the third input to the output of the auxiliary generator , the first input of which is connected. The marker is assigned to the marker circuit, and the second input is assigned to the second control circuit.

The invention relates to seismic techniques for the study of the lithological composition of bottom sediments, and is used primarily in marine geophysical work on the shelf and water areas. A known digital seismic receiver system for land seismic surveys, comprising a field part, which includes a code transmission line, a synchronization line, both continuous, but tapped by the number of channels, and in each channel there is a seismic coding device consisting of a seismic receiver and an analog-digital converter. Each converter is connected with its output to the tap of the data line, and its input to the tap of the synchronizer line. The central station contains receiving shift registers, a recording device in the form of a processor, format conversion and filtering, a strobe synchronizer connected to the synchronization line II. The disadvantages of the system are the complexity of the synchronization channel and the high reliability of the transmission and reception of codes due to the limitations of both devices. lines / transmission, gating pulse generator and coding transducer. The execution and communication of these features of the system allow only one-bit encoding of the seismic signal increment (delta modulation), and since the system belongs to the class of open-loop acoustic telemetry systems, any failure or inaccuracy of the transmission and recording conversion leads to an accumulation of bias and distortion coded seismic signals fixed by the central station. Closest to the invention is a multichannel system for marine seismic surveys, comprising, in the towed part, a radiating acoustic transducer, a code transmission line, a synchronization line, and in each channel a seismic coding device, consisting of a serial connection of a receiving acoustic transducer and an analog-digital converter, and in the side part - a synchronizer, a receiving shift register and a recording device, between which the code correction device is connected, and also a temporary software device connected via a pulse shaper to an acoustic source, a tracking auto-synchronizer connected between the signal and control inputs of the receiving shift register, and in the towed part of the system each device for encoding seismic signals is supplemented by a cyclic code converter, both lines are divided by the number of channels on the segments between which the collecting lines are included in the data lines and the synchronization lines are chains from the delay device and the driver mpulsov, the output of each chain is connected to the clock input of analog-qi rovogo converter, input string. to the triggering input of a cyclic code converter, the output of which is connected to the input of the collecting circuit Uz. The disadvantages of a multichannel system are the complexity of the synchronization channel and the low noise immunity of the transmission channel of codes, due to the presence of a constant component in the spectrum of the transmitted signal. The purpose of the invention is to simplify the device and increase its noise immunity. This goal is achieved by the fact that the device for marine geophysical studies containing, in the towed part, a receiving acoustic transducer, an analog-digital converter and a shift register, connected in series, emitting an acoustic transducer and the transmission line of codes, Shift Register, Recording Device, Marker Allocation Schemes, and Gene Generation) aTop pulse currents are received in its tow | a) a pulse generator, a first control circuit, a marker driver, a bipolar code forger and a first matching circuit, and a second matching circuit, a code converter and a second control circuit, the output of the pulse generator connected to the input of the first control circuit, the first output of which is connected to the control input of the analog-digital converter, and the second output - to the control inputs of the shift register and marker generator, the signal input of the latter is connected to the output the shift register and the signal input of the shaper of the bipolar code, the control input of which is connected to the output of the shaper of the marker, and the output with the input of the first matching circuit, the output of which is connected to the signal inputs of the code converter and the marker's latch circuit via the code transmission line and the second matching circuit , the output of the latter through a synchronizer is connected to the input of the second control circuit, the first output of which is connected to the input of a radiating acoustic transducer via the pulse current generator, and the second output od - with the control inputs of recording device the token release scheme, the receiving shift register, the recorder and the code converter, the output of the last shift register through the receiving signal input connected to the recording device. (H -1), receiving acoustic transducers, analog-digital transducers and shift registers, connected in series, where, 3, 4, moreover, all n shift registers are connected in series with each other on the outputs and the second signal inputs and the driver of the first channel marker, the output of which is connected to the second control input of the bipolar code generator, the signal input to the output of the shift register, and the control input to the output of the first control circuit and control inputs to (h-1) analog-to-digital converters AND shift registers, a channel counter, an auxiliary generator, a channel control circuit and a channel shutdown circuit, a first channel marker extraction circuit are entered in the side, the signal input of the latter connected to the output of the second matching circuit, and the output through the first input of the channel control circuit, the circuit off of the channels and the channel counter is connected to the second control input of the recorder and to its control input, the second input of the channel control circuit ene yield synchronizer, and the third input - to the output of the auxiliary generator, the first input of which is connected to a token release scheme, and the second input - to the second control circuit, Figure 1 shows a block diagram of an apparatus days marine geophysical studies; Fig.2 is a block diagram of a device for marine geophysical surveys with P channels; FIG. 3 shows graphs of unipolar and bipolar signals and their spectra. The device for marine geophysical studies contains a towed part 1, which includes a receiving acoustic transducer analog-digital converter 3, shift register 4, shaper 5 bipolar code, first matching circuit 6, code transmission line 7, pulse generator 8, first circuit 9 control, driver 10 marker and radiating acoustic transducer 11. Receiving acoustic transducer 2 its output is connected to the signal input of analog-digital converter 3, to the control to the input of which, through the first control circuit 9, a generator of 8 pulses is connected. The second output of the first control circuit 9 is connected to the control input of the shift register 4 and through the marker shaper 10 to the shaper of the bipolar code. The output of the analog-digital converter 3 through the signal input of the shift register 4 is connected to the signal inputs of the marker generator 10, and the bipolar code generator 5, the output of the latter is connected to the input of the first matching circuit 6, the output of which is connected to the code transmission line 7. The airborne portion 12 comprises a second matching circuit 13, a marker extraction circuit 14, a synchronizer 15, a code converter 16, a receiving shift register 17, a recording device 18, a second control circuit 19, and a pulse current generator .20. The code transmission line 7 is connected to the second matching circuit 13, the output of which is connected to the signal inputs of the marker circuit 14 and through the code converter 16 and the receiving shift register 17 to the recording device 18. The marker extraction circuit 14 by its output through the synchronizer 15 is connected to the second control circuit 19, the first output of which is connected to the control inputs of the marker extraction circuit 14, the code converter 16, the receiving shift register 17, the recording device 18, and the second output through the pulse current generator 20 to a radiating acoustic transducer 1 1. The device works as follows. The command pulses produced by the second control circuit 19, at equal intervals of time, are supplied to the generator 20 pulsed currents, the current pulses from which are sent to the radiating acoustic transducer I1, where these pulses create probing signals that are perceived and reflected by the bottom and depth formations and are filtered in the acoustic frequency band by the receiving acoustic transducer 2. Immediately with the switching on of the equipment, the generator of 8 pulses is turned on, which is produced The clock frequency supplied to the first control circuit 9, which generates start and read pulses for the analog-digital converter 3 with a sampling frequency, as well as control, write and shift pulses for the shift register 4 and the control pulses of the marker generator 10. The acoustic signal from the receiving acoustic transducer 2 is fed to the input of the analog-digital converter 3, where it is converted into a parallel binary code, which is written to the shift register 4 by a trigger pulse, after which the latter switches to the shift mode. A serial binary code is removed from the output of the shift register 4, which is fed to the marker generator 10 and the bipolar code generator 5. The marker generator 10 produces, from the two first code bits, marker pulses, which are two consecutive positive polarity pulses of a duration equal to the duration of the clock frequency. The marker pulses without polarity changes are transmitted through the bipolar code generator 5 and the first matching circuit 6 to the code transmission line 7. Binary code, pass through the driver. 5 of the bipolar code, is converted into a bipolar, representing the alternation of pulses of negative and positive polarity (Fig. 3). Next, the bipolar code through the first matching circuit 6 and the code transmission line 7 enters the airborne part 12 to the second matching circuit 13. The bipolar code from the second matching circuit 13 is fed to a code converter 16 and a marker selection circuit 14, the latter selecting marker pulses which include a synchronizer 15 assembled according to a standby generator circuit. The synchronizer 15 generates the clock pulses that go to the second control circuit 19, where the reset pulses are generated for the marker and control pulse pulses 14 for the code converter 1, the receive shift register 17 and the recorder 18, as well as the trigger pulses for the pulse current generator 20 . The serial bipolar code, which comes from the second matching circuit 13 to the converter, 16 codes, is converted in the latter into a conventional serial binary code (binary) and written into a receiving, shift register 17f in which it is converted from a serial binary code into a parallel binary code and is rewritten 18 devices are recorded. After the binary code is written to the recorder 18, the setup pulse produced by the second control circuit 19 returns the onboard portion 12 to the initial state, the synchronizer is turned off, and the operation cycle repeats after the next marker pulse. The device for marine geophysical studies (Fig. 2) contains a towed part 1, which includes n identical channels, Which consist in their turn of receiving acoustic transducers 2, analog-digital converters 2i -. registers 4 - 4 ,, owners 3 - 3, shift, as well as shaper 5 bipolar code-a, first matching circuit 6; code transmission line 7, pulse generator 8, first control circuit 9, marker generator 10, emitting an acoustic transducer I1 and driver 2I of the first channel. Receiving acoustic transducers 2 - 2 are connected respectively to the signal inputs of analog-digital transducers 3 - 3, the pulse generator 8 is connected to the control inputs of the last second first control circuit 9, the second output of the first control circuit 9 is connected to the control inputs of the shift registers 4 and through driver 2I Marker of the first channel and shaper 10marker to shaper 5 bipolar code. The outputs of analog-digital converters 3 - 2 are connected to the signal inputs of registers 4 - 4 shift, which are connected in series through the second signal inputs and outputs. The signal output of the shift register 4 is connected to the signal inputs of the first marker marker 21, the marker 10 generator and the bipolar code generator 5, the output of the latter is connected to the input of the first matching circuit 6, the output of which is connected to the code transmission line 7. The code transmission line 7 is connected via the second matching circuit 13 to the inputs of the code converter 16, the first channel token extraction circuit 22, and the token split circuit 14. The output of the marker allocation circuit 22 of the first channel through the first input of the channel control circuit 23, the channel shutdown circuit 24 and the channel counter 25 is connected to the second control input of the recorder 18 and to its control input. The output of the marker circuit 14 is connected via the first input of the auxiliary generator 26 to the third input of the channel control circuit 23 and through the synchronizer 15 to the second input of the channel control circuit 23 and to the input of the second control circuit 19, the first output of which is connected to the input of the emitting acoustic through the generator 20 the converter 11, and the second output - with the control inputs of the recording device 18, the receiving shift register 17, the auxiliary generator 26, the marker cleaving circuit 14 and the 16 code converter, the output n Latter through priemsh 1st shift register 17 is connected to the signal input of the recording unit 1B. The device works as follows. The command pulses produced by the second control circuit 19, at equal intervals of time G are fed to the generator 20 pulse currents, the current pulses from which are sent to the radiating acoustic transducer 11, where probing signals are created which, after reflection by bottom and depth formations, are perceived and amplified and sound out in acoustic polo9

all frequencies of receiving acoustic

Converters 2 by switching on the equipment turn on a generator of 8 pulses, which produces a clock frequency supplied to the first control circuit 9, which generates start-and-read pulses for analog-to-digital converters. 3–3 with a sampling frequency as well as control, recording and shift pulses for registers 4, –4 shifts, control pulses by the shaper 10 of the marker and the shaper 21 of the first channel marker. The acoustic signal from the receiving acoustic transducers 2p is fed to the inputs of analog-to-digital converters 3 and is converted into a parallel binary code, which, by a write pulse, is rewritten into h of registers 4 - 4.J. In this mode, all registers are enabled in parallel. After writing the current value of the binary code into the 4–4 shift registers, the latter are switched to the read mode. In this mode, the 4–4 shift registers are connected in series with the communication line, i.e. the output of the latter is connected to the input of the previous one, and so on. In this case, the serial binary code is removed from the output of the first shift register 4.

8 readout first circuit

9 control generates a packet of pulses with, equal to the product of the number of channels and the number of bits of the ADC K

(.K + m),

Where.t- marker pulses that distinguish one channel from another.

Dp of determining the start of transmission, before switching on the transmission of codes, the pulses of the first token are transmitted, which are generated by the shaper 21 of the first channel dp dividing the channels at the reception, before transmitting the code of any of the n channels, the pulses of the token generated by the shaper 10 of the token are transmitted. Further work takes place as in the single-channel system, i.e. The binary code is fed to the driver circuit 5 of the bipolar code, and the bipolar code through, the first matching circuit 6 and the code transmission line 7 is transmitted on board the vessel.

3877410

The on-board part 12 of the system is connected to a code towed via line 7 and a second matching device 13. The bipolar code from the second matching circuit 13 is fed to a code converter 16, which converts the bipolar code to a binary code, as well as to the marker 14 and the allocation Q of the marker of the first channel 22. The circuit 22 for extracting the marker of the first channel allocates pulses of the marker of the first; the channel and generates an impulse to turn on the marker emit 14 circuit and the channel control circuit 23. The marker extraction circuit 14 results in pulses of the channel marker, which include the synchronizer 15, the clock frequency from which is available to the channel control circuit 23 and the second control circuit 19.

The current value of the binary code from the 16 code converter is fed to the receiving shift register 17, in which it is converted from a serial binary code into a parallel binary code, and the control pulses from the second control circuit 19 are written into the cell recorder 18 corresponding to this channel. The channel control circuit 23 generates pulse pulses, which are fed to the channel shutdown circuit 24 and the counter of 25 channels. When one or several channels are turned off 5, the channel shutdown circuit 24 blocks the pulses, and the 25-channel counter generates a prohibition signal that inhibits recording of the current. code in the data device 18 records. The pulses of the auxiliary generator 26, the frequency of which is equal to the frequency of the synchronizer 15-, are supplied to the channel control circuit 23, which, in the event of a malfunction or disconnection of the channel, generates a channel switching pulse through the channel shutdown circuit 24 to the counter 25 channels. 0 This is done to eliminate possible failures in the recording device and Accordingly, the entire device as a whole, since in the event of one or several channels failing, the split marker circuit 5 18 is turned off for the time of the failure, and the channel mark pulses are blocked. The channel shutdown circuit 24 is designed to shut off any of the channels in the event of a malfunction or if it is necessary to reduce the number of operating channels. With the arrival of the next pulse of the channel marker, the synchronizer 15 is turned on, and the auxiliary generator is turned off, and the cycle of operation is repeated. With the arrival of the last pulse of the marker, the system performs the last cycle, after which the channel counter 25 generates a reset pulse of the first analog marker 22, and the second circuit 19 control — a reset pulse of circuit 14 of marker and converter 16 codes, i.e. the device is set to its original state, until the next pulse of the first channel marker arrives, after which the whole cycle of operation is repeated. A large number of different types of code sequences have been developed for the connection of objects. For a system with quantization, binary phase coding G bipolar codes are most convenient for communication, since this achieves an optimal receiver voltage with standard digital signal processing circuits and the best interface with currently used computers with a binary number system. To increase the reception resolution, it is necessary to apply waveforms for which the function R (t, f) satisfies two conditions: it must be close to -1 only in a small neighborhood of the point t, f 0, in all other areas of the t plane , f the module of this function should be significantly less than one. These conditions allow to resolve the contradictions between the requirement of high noise immunity and high accuracy or resolution of the receiver. At the same time, the bipolar codes (FM signals) have the greatest potential noise immunity. Indeed, two signals having the same power and differing on L radians have the greatest possible degree of difference. The function of their mutual correlation in the absence of a time shift is -1, which is why the use of such signals in the transmission of discrete messages provides the greatest noise immunity. For the same reason, systems with noise-like FM signals are classified as high-performance telemetry systems, which allow processing by the maximum likelihood criterion and minimize the likelihood of error in cases where all signals are uniform and have the same energy. The use of a bipolar code allows to ensure the highest noise immunity of the system and the reliability of the received signals, while the constant component is excluded from the spectrum of 1 to 1X signals. Greater noise immunity and reliability of the received signal can significantly simplify both the onboard and outboard equipment.

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Claims (2)

1. DEVICE OF MARINE GEOPHYSICAL RESEARCH DAY, containing in the towed part a receiving acoustic transducer, an analog-to-digital transducer and a shift register connected in series, a radiating acoustic transducer and a code transmission line, and on-board part - marker extraction circuits, a synchronizer, a receiving shifting register, a recording device and a pulsed current generator, characterized in that, in order to simplify the device and increase its noise immunity, a generator is introduced into its towed part pulses, the first control circuit, the marker driver, the bipolar code generator and the first, matching circuit, and to the side, the second matching circuit, the code converter and the second control circuit, the output of the pulse generator being connected to the input of the first control circuit, the first output of which is connected to the control input of an analog-to-digital converter, and the second output - with the control inputs of the shear register and marker former, the signal input of the latter is connected to the shift register output and the signal input a bipolar code shaper, the control input of which is connected to the output of the marker shaper, and the output is connected to the input of the first matching circuit, the output of which is connected to the signal inputs of the code converter and the marker allocation circuit through the code transmission line and the second matching circuit, the output of the latter through the synchronizer is connected to the input the second control circuit, the first output of which is connected through the pulse current generator to the input of the emitting acoustic transducer, and the second output is connected to the control inputs of the device recording, the receiving shift register, the allocation circuit marker and code converter, the output of the latter through the receiving shift register is connected to the signal input of the recording device. 2. The device according to π.1, characterized in that in the towed part additionally (p-1) receiving acoustic transducers, analog-to-digital converters and shift registers are connected in series, where ή = 2, 3, 4, in addition, all h shift registers are connected in series between the outputs and the second signal inputs, and the marker former of the first channel, the output of which is connected to the second control input of the generator of the bipolar code, the signal SU “1138774 input is to the output of the shift register, and the control input is to the output of the first control circuit and the control inputs of the entered (n-11 analog-to-digital converters and shift registers, the channel counter, auxiliary, generator, '' channel control circuit and channel shutdown circuit, marker allocation circuit of the first channel, the signal input of the latter being connected to the output, the second matching circuit, and the output through the first input of the channel control circuit, channel shutdown circuit and the channel counter connected to to the second control input of the recorder and to its control input, the second input of the channel control circuit is connected to the output of the synchronizer, and the third input is connected to the output of the auxiliary generator, the first input of which is connected to the marker allocation circuit and the second input to the second control circuit.