SU1241175A1 - Multichannel digital piezoseismometric cable - Google Patents

Description

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The invention relates to technical physics, in particular, to technical means for conducting marine geophysical work.

The aim of the invention is the ease of manufacture, operation and maintenance of a multichannel digital piezoelectric mowing device, as well as simplifying the braid and reducing its mass by eliminating a lengthy test line.

FIG. 1 shows the principle of constructive division of a digital braid into assembly units; in fig. 2 - structural diagrams of its basic electronic units.

The digital piezo seismometric streamer consists (Fig. 1) of data transmission line 1, synchronization line 2 and control line, which are routed inside filled with a liquid dielectric, hose sections 4 of flexible plastic x, sealed in end coupling halves 5 by means of metal-glass plugs of electrical connectors 6, and from channel coding blocks, each of which includes at least one piezoelectric seismic receiver 7 and an electronic module 8. Seismic receiver 7 is usually made up of a group of and distributed along the length of the sectioned hose and piezoceramic hydrophones connected in parallel, and the electronic module 8 structurally contains (Fig. 2) switch 9 having at least two symmetrical signal inputs 10, 11 and a control input 12, an amplifier 13 with a symmetrical input and output , analog-to-digital converter (ADC) 14, to. contacting input and output. which, respectively, the triggering output I5 and the receiving input 16 of the compaction and regeneration device 17 are connected. Neighboring segments 1 of the transmission line and adjacent segments of the synchronization line 2 in pairs (Fig. 1) are interconnected via corresponding pairs of pins 18 19 and 20, 21 of the electronic module 8, for example, in the compaction and regeneration device 17 from the inputs and output of the collecting circuit as well as the output of the signature combining circuit and the input of the signature separation circuit.

The electronic module 8 also contains a level recovery circuit 22.

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175 2 signals through which adjacent pairs are connected by connecting to the corresponding pair of pins 23 and 24

segments of line 3 control. Signal input 11 (FIG. 2) is connected to the output of a start-stop generator 25 of a sinusoidal signal, which can be performed, for example, as a serial connection of a standby pulse generator 26 and a high-order analog low-pass filter 27 with a balanced output. The building input 28 of the generator 26 sub-keys to the output 24 of the module 8.

Structurally, the electronic module 8 and the generator 25 are enclosed in a cylindrical sheath 29 (Fig. 1) of metal with end sockets of electrical connectors 6, mating by means of an annular elastic seal 30 of a fixed contact type with coupling half 5 of adjacent hose sections 31 that are coupled with the tails of coupling half 5 by means of a fixed maze-type compaction, conventionally shown in FIG. 1 in the form of rounded protrusions. The degree of compaction is ensured by tightening nuts 32 and 33. In the cavity of sectional hose 31, a differential active bandpass filter 34 is placed, sealed, for example, by compounding, which is made in the form of two operational amplifiers 35, between the output and the inverting input of each of which are included identical parallel ones. The EC-chains 36, 37, between the inverting inputs, are sequential RC-chains 38, 39, and the non-inverting inputs of the amplifiers 35, which serve as the inputs 40 of the filter 34, are connected through equal equalizing resistors 41 to the common power supply bus. In this case, the time constant of the successive HC-chain 38, 39 is chosen much less than the product of the own capacity of the geophone 7 by the double resistance of the matching resistor 41. The lower cut-off frequency of the bandpass filter is determined by the time constant RC 38, 39, and the upper cut-off frequency is constant RC 37, 36. The frequency of the oscillator 26 is selected in a region where the amplitude-frequency characteristic of the bandpass filter 34 has a flat top, for example, in the middle of its passband.

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The device works as follows.

The spit channel is structurally made in the form of two types of assembly units: the spit rod section with nearly j coupling halves and the cylindrical coupling shell, At the same time, along the electrical circuit (Fig. 1, 2), the sections 1 and 2 of transmission and synchronization are switched on through the device 17 tO in series, the segments of the control line 3 through the circuit 22 also in series. Failure (break, loss of contact with connector 6, breakage) of any of the constituent parts of such a serial connection t5 is diagnosed by the loss of a signal from a group of channels, starting from the failed to the terminal.

Electrical and electronic components 20 (7, 34, 6) of the spit section and. The corresponding transducer nodes (9, 13, 14, 25) are connected relative to the device I7 in series-parallel, but are located in jy-spit assembly units of different types. Local diagnostics of faults in a series-parallel part of an assembly unit is provided by nodes 34 and 25. Q

The nominal intrinsic input resistance of the sealed filter 34 is stable and determined with respect to the inlet 40 by the double resistance of the resistors 41. When the liquid dielectric in the internal hose tube is wetted, which can occur, for example, through a seal. Neither 33 at the depth of the spit, bypassing the input with 40 equivalent-40 leakage resistance occurs. The constant time of the input circuit is equal to the product of the seismic receiver's own capacity and equivalent resistance relative to input 40, 45 decreases, which leads to a weakening of the energy of the useful signal separated by the bandpass filter 34. This begins to occur when said time constant in emergency channel 50 is compared with RC time constant 38, 39, and almost complete attenuation, observed as a complete parametric failure, occurs when the time constant of the input circuit becomes less than RC value. 37, 36. You can see that the emergency changes occurred in the section, you can when

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giving a control signal of the type logical 1 through segments of the 3 control lines. In this case, a waiting pulse generator 26 is turned on, the first harmonic of the output signal of which is extracted by filter 27 and in the form of a sinusoidal voltage is fed to input 11 of switch 9. The latter is controlled by input 12 by a voltage of logical 1 control signal, the level of which in each channel is restored by a circuit 22, connects through the amplifier 1.3, coding in the ADC 14 a sample of a sinusoidal signal and subsequent transmission through segments 1, channel devices 17 in digital multiplex form to the ship. It produces, with demultiplexing, restoration of the signal in analog form and evaluation of its parameters. With undistorted transmission and nominal parameters of a sinusoidal control signal, a failed sectional assembly unit is uniquely diagnosed in all channels with a large attenuation due to leakage from the dewatering of the dielectric. Repair will require replacing the section. If on all channels, except for the emergency one, identical sine-wave control signals are sent to the onboard recorders, then the failure of the transforming part (nodes 9, 13, 14, 22) of the electronic module or generator 25 is diagnosed. its contents.

In addition, the cause of the failure may be the wetting of the connector 6 due to the deterioration of the quality of the seal 30, which may jointly affect the mated electrical components of the section and the cylindrical shell. This factor can have the greatest influence on the leakage between the contacts of the transmission circuits of analog signals, since segments 1, 2 and 3 of the transmission lines of logical signals are matched by wave impedances (75 or 150 Ohms) much lower than the possible leakage resistance when the connector is wetted. To reduce the effect of leakage in connector 6 on the transmission of an analog signal, the filter 34 is signaled active, its output impedance is equal to the output impedance.

terminal cascade divided by the depth of negative feedback through RC chains 37, 36-38, 39. The depth of negative feedback is maximum outside the transmission band. At low frequencies, the resistance of the RC chain 38, 39 increases, and at higher frequencies, the resistance of the HC 37, 36 decreases. In the passband, the depth of the negative feedback decreases, which increases the sensitivity of the sealed filter to the humidification of the connector. When the critical leakage resistance value of 2 kΩ is reached, the signal passing through the amplifier is accompanied by distortions such as the threshold limits of the signal from above, which makes it possible to ascertain the cause of the failure. , -1l repair requires replacement of the seal 30.

The useful effect in the proposed digital streamer is achieved as follows.

The constructive separation of the spit channels (Fig. 1.2) into 2 types of assembly units, together with the introduction of the sealed bandpass filter 34 and the start-stop generator 25, allows the electrical connector 6 to have an unpressurized socket rigidly fastened to the mechanical structure (frame) of the internal cylindrical inter muffle - howl shell 29. The latter becomes repairable and contains almost all the electronic equipment of the channel. This reduces the cost and makes it convenient to manufacture, operate and repair a digital streamer, simplifies the introduction of the embedded start-stop monitoring generator 25 to its wired system, reduces the weight of the streamer, improves its buoyancy conditions and productivity of geophysical work due to the possibility of increasing the speed of the ship when towing a smaller mass overboard. The internal cavity of the cylindrical shell has a diameter greater than the diameter of the cavity of the hose, and creates a number of design advantages of a production nature and with a prospective increase in the level of miniaturization of the electronic module in combination with the expansion of its functionality.

Formula a-isobre T eni

Claims (2)

1. A multichannel digital piezo-J seismometric streamer, electrically consisting of data transmission line segments, a synchronization line and a control line, laid inside pin-10 pin sections filled with a liquid dielectric with sealed forks in the end coupling halves, and from channel coding blocks, each of which includes at least one ts piezoelectric seismic receiver and electronic module containing a series-connected switch, amplifier and analog-to-digital converter to a clocking input 20 and the output of which, respectively a triggering output and a receiving input of a compaction and regeneration device are connected, a level matching circuit, the output of which is electrically connected with 5, the control input of the switch, where the seismic receiver is placed inside the hose section, the adjacent segments of the transmission line and the adjacent segments of the synchronization line are connected in pairs through the corresponding pairs of outputs of the compaction and regeneration device, and the adjacent segments of the control line are connected to the input and the output of the level matching scheme, which is different from the fact that, for the purpose of ease of manufacture, operation and repair, a sealed differential active strip is inserted into each sectional hose a filter, and each electronic module is supplemented by a start-up sinusoidal signal generator with a symmetrical output, the electronic module and the generator are enclosed in a cylindrical shell with end sockets of electrical connectors, which are coupled by means of a fixed contact type to the semi-couplings of adjacent hose sections, and a seismic receiver is connected through diff. The active active bandpass filter is connected to the first signal input of the switch, the second signal input of which is connected to the output of the generator, the gate input of which is connected to the output of the level matching circuit. 2. Spit according to claim I, as follows: that the differential five 0 five 71241 the active band-pass filter is made in the form of two operational amplifiers, between the output and the inverting input of each of which identical identical RC circuits are connected, between the inverting inputs there is a series of RC circuits, and the non-inverting inputs of the amplifiers serving as inputs 758. filter, are connected via equal terminating resistors to the common power bus, and the time constant of the sequential RC-circuit is chosen much less than the product of the seismic receiver's own capacity by the double resistance of the terminating resistor. l Jznij ABOUT