SU1013883A1 - Digital seismic registering system - Google Patents

Abstract

DIGITAL SEISMICATION RECOGNITION SYSTEM, containing a series-connected towing digital receiver, on-board digital receiver and digital filter, as well as a recorder, a unit for detecting the law of signal frequency change, sources of undermining and sampling pulses, so that the express analysis of the received information entered devices in the decimation and filter control unit, while the signal input of the decimation device is connected to the output of the digital filter, the output of the decimation device is connected to the input of the recorder, the output of the detection unit of the law of signal frequency variation is connected to the input of the filter control unit and the first control input of the decimation device, the second control input of which and the first control input of the signal detection unit of the law of frequency change of the signal are connected to the output the source of sampling pulses, the signal input of the detection unit (A of the law of changing the signal frequency is connected to the output of a digital filter, the control input of which is connected to the output of the filter control unit, and the second control input of the detection unit for the law of change of the signal frequency is connected to the output of the source of pulses. oo 00 00 co

Description

The invention relates to a seismic recording technique for radiated subsurface formations and can be used in marine geophysical work on the shelf, in water, and in the ocean. A well-known digital geoacoustic station for land seismic exploration, in which the effect of absorbing high :: frequencies of the emitted signal when propagating deep into the earth is used to reduce the volume of the regimenter signals without loss of information content. In addition, the longer the duration of the received signal, the more reduced the cut-off frequency, which allows the use of a variable sampling interval of analog information Ij. This device implements the statistical principle of processing information to increase the signal-to-noise ratio, which consists in that received signals representing a mixture of repeated repetition to the desired signal and noise are first digitized and stored for a period of time. between the two emissions, and then the values obtained / of the first realizations are summed over the corresponding time samples with the values of the subsequent realizations, and all the obtained values are averaged by the number of summarized lizatsy. However, the principle of statistical accumulation for marine conditions, where the geoacoustic station in connection with the towing conditions of the receiving device is in continuous motion, is practically not implemented in real time. The consequence of this is the impossibility of reliable rapid analysis of the received signals in the process of reception due to the impossibility of improving the signal-to-noise ratio, which does not allow the use of a similar staniyu for direct mineral exploration by analyzing the dynamic properties of each received signal. each local seabed area. A known multichannel digital system with a registrar system comprising a towed digital device onboard, a digital receiver and a digital filter connected in series, as well as a recorder, a unit for detecting the law of signal frequency variation, sources of undermining and sampling pulses, where digital signal filtering is used for each received signal in the entire band of the hours occupied by this signal 21. But over time, the reflected seismic signals are absorbed deep in the sedimentary sequence, the upper frequency components lose, and the reliability of the express analysis is possible. increase by increasing the signal-to-noise ratio by automatically adapting the digital filter to the received signal. The purpose of the invention is to increase the reliability of express analysis of the received information. The goal is achieved by introducing a decimation device and a unit into a digital seismic recording system containing a serially connected towing digital receiver, an onboard digital receiver and digital file, as well as a recorder, a unit for detecting the law of signal frequency variation, sources of undermining and sampling. filter control, the signaling device of the puncturing of the decimator is connected to the output of the digital filter, and the output of the device is thinned and connected to the input of the recorder, The output of the signal frequency detection unit is connected to the input of the filter control unit and the nepBbiM control input of the decimation device, the second control input of which and the first control input of the signal frequency law detection unit are connected to the output of the digital filter whose control input is connected to the output of the filter control unit, and the second control input of the block for detecting the law of signal frequency variation is connected to the output of the source of undermining pulses. FIG. 1 shows a block diagram of a digital seismic monitoring system / FIG. 2 is a block diagram of a thinning device; in fig. 3 is a block diagram of the detection of the law of signal frequency variation; in fig. 4 shows the signal plots and traffic, explaining the principle of operation of the decimation device, the block for detecting the law of change in the signal frequency and the system as a whole. The digital seismic recording system (Fig. 1) contains towed series connected in series. a digital receiver 1, an on-board digital receiver 2 and a digital filter 3, as well as a recorder 4, unit 5 for detecting the law amended. signal frequencies, sources of undermining pulses 6 and sampling 7, decimation device 8 and filter control unit 9, the signal input of decimation device 8, the output of which is connected to the input of recorder 4, is connected to the output of digital filter 3, output of the change law detection unit 5 the frequency of the signal is connected to the input of the control unit 9 by a filter and the first control input of the decimation device 8, the second control input of which is and. The first control input of block 5 for detecting the law of signal frequency variation is connected to the output of source 7 of sampling pulses, and the signal input of block 5 for detecting the law of frequency variation of the signal, the second control of which input is connected to source of 6 pulses of detonation, is connected to the output of digital filter 3, the control input of which is connected to the output of filter control block 9. The device (Fig. 2) 8 decimation contains frequency divider 10, AND 11 elements, OR 12 element and memory register 13, while the divider 10 frequency input and The first input of the first terminal And 11 is connected to the output of the source 7 of sampling pulses, the outputs of frequency divider 10 are connected to the first inputs of the remaining elements of And 11, and the second input of all elements of And ii are connected to the outputs of the block 5 for detecting the law of signal frequency variation, and the outputs of the elements And 11 is connected to the inputs of the element OR 12, the output of which is connected, to the control input of the memory register 13, the input of which is connected to the output of the digital filter 3, and the output is connected to the input of the recorder 4.

Block 5, you follow the law of frequency variation of the signal of FIG. 3) contains two elements AND 14 and 15, two counters 16 and 17 pulses, memory cakes 18, elements OR 19 and undermining trigger 20, with: this the first inputs of the elements, AND 14 and-15 are connected to the output of the source 7 of sampling pulses, the second inputs to the direct and inverse outputs 4 trigger digital filter sign 3, the output of the element And 14 is connected to the input of the pulse counter 1 and with the input Set to zero the counter of 17 pulses, the output of the elements 15. And connected to the input of the pulse counter 17 of the pulses and with the input Setting the counter to 16 pulses to zero, the outputs of the counters 16 and 17 pulses connect Unca with inputs Installations

.in the unit of memory cells 18, the output of the lower cell 18 of the memory is connected to the input of the Zero trigger 20, the input of the Unit into the trigger 20, the input of the high cell 18 of the memory and the input of elements

OR 19, the outputs of which are connected to the inputs of the installation in the zero of the remaining memory cells 18, are connected to the output of the source-ik 6 undermining pulses, the output of each subsequent

memory cells 18 are connected to the inputs of the elements OR 19 previous memory cells 18.

The memory cell 18 (FIG. 3) contains two triggers 21 and 22 and an AND 23 element, while the Installation inputs into the unit of the trigger 21 and 22 are connected to the outputs of the counters 16 and 17 pulses, respectively, and the Installation inputs to zero — to the output of the OR element 19, and the outputs of the flip-flops 21 and 22 are connected to the inputs of the elements AND FROM.

FIG. 4 shows the signal 24 of the source 6 of undermining pulses, the law 25 of changing the frequency of the reflected signal, the law 26 of changing the upper cut-off frequency of the digital filter 3 and the output signal 27 of the element OR 12 of the decimation device 8.

Digital seismic recording system operates in the following way.

The reflected signal is received by the towing digital receiver 1, converted into digital form and transmitted by serial-binary code to the input of the onboard digital receiver 2, where the information is converted into parallel binary codes, which are fed for processing to the input of digital filter 3.

The towed digital receiver 1, the onboard digital receiver 2, and digital filter 3 operate with a constant minimum sampling interval of 1/1 (F, where K 3-5; gr is the maximum limiting purity of the spectra signal), which simplifies the coupling of the towed digital receiver 1, with the on-board system, reduce the noise and error of the digital filter 3.;

The input of the block 5 for detecting the law of frequency variation of the signal from the output of the digital filter 3 receives information about the sign (sign) of discrete readings of one of the system channels. In this case, the change in the law of variation of the frequency 25 of the output signal of the digital filter 3 is performed by the method of counting zeros, i.e. measurement of time intervals between changes of the sign of discrete samples.

Block 5 for detecting the law of change; the frequency of the signal at each of the time intervals between two emissions (1 / F) at times t (i 0,1, ..., n), corresponding to a decrease in the cutoff frequency of the signal by 2 times, generates output signals that go to the control the inputs of the decimation device 8 and the inputs of the filter control unit 9 ..

The discrete reduction of the sampling frequency Fj and the upper cut-off frequency F of the digital filter 3 by a factor of 2. 2 at times t simplifies circuit design of the decimation device 8, the filter control unit 9 and the signal frequency detection law detection unit 5, as well as reduce transients, In the digital filter 3 at the time points t .., the device 8 decimation of the law of changing the frequency of the signal at each of the time intervals t produces the output signal 2 7C with a pulse repetition rate that enables the census of information from the output of the digital filter 3 to recorder 4, and this results in a decrease in the volume of recorded signals without loss of information content. The BLOCK .9 filter control, the output of which receives control signals from the output of block 5 of detecting the law of change in the frequency of a signal, at times t- at its output, generates a potential signal. which produces a discrete decrease in the law of variation of the upper cutoff frequency 26 of a digital filter by a factor of 2, which is an increase in the signal-to-noise ratio, i.e. reliability of the received information increases. The decimation device 8 (Fig. 2) operates as follows. Under the action of the output signals of block 5 of detecting the law of change in the frequency of a signal arriving at the second inputs of elements 11, in the time interval tj - t- one of elements 11 11 is opened, to the second input of which frequency from the output of frequency divider pulses the element OR 12 at the same time, the pulses of this frequency are formed, which are fed to the control input of the register 13 of the memory. The unit 5 for detecting the law of frequency variation of the signal (Fig. 3) operates as follows. From the output of digital filter 3 to the signal input of block 5 for detecting the law of signal frequency variation, information about the sign (sign) of discrete samples of one of the system channels is received. The counters 16 and 17 pulses under the action of the output signals of the elements and 14. and 15 count the number of pulses of frequency P between the changes of the sign of the discrete channel samples. If the number of positive and negative counts exceeds the threshold value Hldr {(Krl), then the corresponding outputs of meters 16 and 17 pulses generate signals that set one of the memory cells 18 to state one and the signal t is generated at the output of the latter. allowing the reduction of the sampling frequency at the output of the decimation device 8 and the upper cut-off frequency F of the digital filter 3 to 2 times. In this case, the remaining memory cells 18 and the blasting trigger 30 are set to zero. Setting the state of the trigger unit 20 and in the state of zero memory cells 18 in the system is produced by the output signal 24 of the source b of the blast pulses. By the action of the output signal of the trigger 20 for undermining the time interval (tj-t) in digital filter 3 sets the initial maximum upper cut-off frequency FCP lax, and the output of the OR element 12 (Fig. 2) of the decimation 8 produces an output signal in the form of a pulse sequences 27 with frequency. Thus, the use of the proposed device allows to significantly increase (by increasing the signal-to-noise ratio at the output of digital filter 3) the reliability of the express analysis of the received information, which allows t use the system for searches of the straight is-dig and dramatically improve the efficiency and effectiveness of geophysical studies of the sea.

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Claims (1)

A DIGITAL SEISMIC RECORDING SYSTEM containing a towing digital receiver, an on-board digital receiver and a digital filter, as well as a recorder, a unit for detecting the law of change of signal frequency, sources of pulsing and sampling, characterized in that, in order to increase the reliability of express analysis received information _χ introduced devices in thinning and filter control unit, while the signal input of the thinning device is connected to the output of the digital filter, and the output thinning device is connected to the input of the recorder, the output of the law frequency change detection unit is connected to the input of the filter control unit and the first control input of the thinning device, the second control input of which and the first control input of the signal frequency change detection unit are connected to the output of the sampling pulse source, and the signal the input of the law frequency change detection block is connected to the output of the digital filter, the control input of which is connected to the output of the control unit detecting filter and the second control law input detection unit changes the frequency of the signal connected to the output pulse detonation source. 1 SU „.1013883 on the shelf, water areas and digital geoacoustic for land seismic survey with the aim of reducing