SU1635153A1 - Device for calibrating seismic channels - Google Patents

Abstract

The invention relates to seismometry and is intended to monitor seismic channels without interrupting the process of recording seismic signals. The purpose of the invention is to increase accuracy while simultaneously increasing the accuracy of the calibration accuracy. The device contains a seismic channel (IC), channel switch. analog-to-digital converter, digital recorder, generator and scaling unit, block of normalizing amplifiers and adaptive digital notch filter. In the proposed device, along with calibration of ICs with voltages exceeding the level of microseismic background, calibration of SCs with voltage equal to and less than the level of microseismic background is provided due to the amplitude normalization by the block of normalizing voltage amplifiers at the ADC input and separation of sinusoidal components from the response SC calibration effect of an adaptive digital notch filter 1 C.p.-ly, 2 silt WITH S

Description

The invention relates to seismometry and is intended to monitor seismic channels without interrupting the process of recording seismic signals.

The purpose of the invention is to improve the accuracy of calibration of seismic channels while simultaneously increasing efficiency and reliability.

FIG. 1 and 2 show the diagrams of the proposed device and adaptive digital notch filter. The device contains calibrated seismic channel 1, generator 2, adaptive digital notch filter 3, scaling unit 4, switch 5 channels, block b of normalizing amplifiers, analog-to-digital converter 7, digital recorder 8 , a device address decoder 9, a data output register 10, a microprocessor 11, an address register 12, read-only memory 13. random access memory 14, a main transceiver to 15.

Generator 2, scaling unit 4, calibrated seismic channel 1, switch 5 channels, block b of normalizing amplifiers, analog-digital converter 7 adaptive digital notch filter (ACRF) 3, digital recorder 8 are connected in series. In addition, the second output of the generator 2 is connected to the second input of the ACRF 3, the output of the scaling unit 4 is connected to the second input of the switch 5 channels, the second output of the block 6 is normalized

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of the amplifiers connected to the second input of the digital recorder 8

The input of the main transceiver ADC 15 is the first input of block 3, which is connected to the LCP 7. The input of microprocessor 11 is the second input of the block that is connected to the generator 2, the output of the data output register 10 is the output of the block that is connected to the digital register torus 8; the input-output of the microprocessor 11 is connected to the first input of the address register and to the first input of the data output register 10, it is also connected to the outputs of the ROM 13, the RAM 14 and the main transceiver 15; The input of the address 12 address and the first inputs of the ROM 13 and the RAM 14 are connected to the input of the device address decoder 9, the five outputs of the decoder 9 are connected to the five inputs by the third input of the address register 12 and the second inputs of the ROM 13, the RAM 14, the main cable - ATSP 15 emo-transmitter and data output register 10.

The device works as follows.

A sinusoidal calibration voltage of a given frequency from the output of the leneparopa 2 is fed to the scaling unit 4. In scaling block 4, the amplitude of the calibration signal is selected depending on the value of the transfer coefficient of the calibrated seismic channel (CK) 1 at a given frequency and the calibration mode. When calibrating SC 1 without interrupting the recording of seismic events, the amplitude of the sinusoidal calibration signal at the output of scaling unit 4 is set equal to or less than the amplitude of the microseismic background, while calibrating with interrupting the recording, the amplitude of the sinusoidal calibration signal is set to Poland, the amplitude of the microseismic background, but 1, the signal amplitude from the output of the channel switch (CC) 5 corresponded to the full scale of the analog-digital converter 1 (ADC) 7. From the output of the block A ma The voltage of the sinusoidal calibration signal is fed to the input of QC 5 and the calibrated channel SC 1. The response of IC 1, which is an additive mixture of the sinusoidal calibration signal and the microseismic background, connects through the QC 5 to the input of block 6 of normalizing amplifiers QC 5 alternately connects to BNU 6 sinusoidal calibration signal and the response of SC 1. In BNU 6, the amplitude was normalized (brought to the full scale of the ADC) of the calibration signal and the response of SC 1 and the amplitude was formed in accordance with the selected range s range conversion code. The generated code from the output 2 BNU 6 is fed to the second input of the digital recorder 8.

ADC 7 converts samples to digital.

The code and numerical codes of these samples are then sent to the ACRF 3.

ATSFR 3 processes the encoded samples of the response of the SC 1 and the original

the calibration signal of a given frequency, coming from the ADC 7 in accordance with an algorithm that allows to extract a sinusoidal calibration signal from the response SC 1. From the second output of the generator 2 to

the third ADRC 3 interrupt signal is received, which allows synchronization of the processing of coded samples from ADC 7 and ADRC 3.

From the output of the ATSRF 3, the processed digital codes of the original and selected sinusoid samples are fed to the first input of the digital recorder 8, to the second input it receives the code of the conversion range from the second output of the BNU 6. CR 8 produces

analysis of the conversion range code and, depending on its value, restores the digital coding of samples of the original CK 1 sinusoids selected from the response and received at the first input. After restoring the digital codes, LR 8 calculates the values of the amplitudes of the sinusoids and determines the values of the CK 1 transmission coefficient at a given frequency

After determining the transmission coefficient 8 by the digital recorder at one frequency in generator 2, another frequency of the sinusoidal calibration signal is set, the measurement cycle is repeated until the full determination of the frequency response.

Adaptive digital notch

filter 3 produces a sinusoidal calibration signal from the additive mixture of a sinusoidal calibration signal and a microseismic background

To implement an adaptive digital notch filter, a sinusoidal voltage with a given frequency of a sinusoidal calibration effect must be applied to the input of the filter. Updating the weights W1J and W2j during the filter adaptation process is described by the Widrow-Hoff equation

Wij4 1 - Wij + 2 / Ј, -Xij, (1)

W2j 1 - W2j 2 / Јj X2j, (2)

where xij, x2 | - samples in the reference channel described by the equations:

Xi | A Cos (ш0 jT + р), (3)

X2j A Sin (Wo / T + p), (4)

where (l - constant filter adaptation time;

EJ - error signal between the desired filter response and the signal at the main input;

ctfe is the natural frequency of the filter;

T is the sampling period.

A is the signal amplitude.

The natural frequency of the filter ai in this case corresponds to the frequency of the sinusoidal calibration signal.

In the permanent storage device (ROM) 13 of the filter, a table of sinusoidal function codes is recorded, which are used to form a reference in accordance with formula (4). The generation of sample codes Xij, X2 is performed as follows. The input of the microprocessor 11 receives the Interrupt signal from the second output of the generator 2, through which the microprocessor 11 generates the address (Z) of the memory cell of the ROM 13 and records the address in the address register 12. At this address, the readout code X2 is read from the ROM 13 in the microprocessor 11 | Then, in the microprocessor 11, the number 256 is added to the generated address and the newly formed address is sent to the address register 12, from which the readout code Xij is read from the ROM 13 to the microprocessor 11. The addition to the contents of register 12 of the address 256 is due to the fact that the functions sin t and cos and t are shifted between

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 The adaptation time of the LCRC 3 r is stored in ROM 13. In the course of the operation of the RDC 3, the weights are calculated in accordance with the above ratios, then the count code of each filter input is calculated, and then the count codes are transferred from the microprocessor 11 to the output register 10 data and then to the input of the digital register 8. To the input of the main transceiver (ADC) 15, which matches the input of the ADRF 3 and the output of the ADC 7, the sampling codes come from the ADC block 7. The decoder 9 of the device address synchronizes the bot of all the ACRF 3 nodes. The random access memory (RAM) 14 is used to store intermediate results of the calculation of the weight coefficients Wij and count codes Xij, X2j.

The device provides high accuracy of determining the frequency response of the calibrated seismic channel, both in interrupted and non-interrupted seismic events, due to that.

that the ACRF 3 allows a sinusoidal calibration signal to be extracted with high accuracy from the response of the IC 1, and due to the normalization of the amplitude of the sinusoidal signal and

response IC 1 at the input of the ADC 7.

The high accuracy of the CK 1 calibration is provided by the ability to calibrate relatively small amplitude sinusoidal calibration signals, which reduces the likelihood of the CK 1 coil coming out of the working area of the linearity of the seismic channel converter magnet.

Claims (2)

1. A seismic channel calibration device containing a seismic cable, a channel switch, an analog-to-digital converter, a digital recorder, a generator and a scaling unit, the seismic channel output being connected to the first input of the channel switch, the first generator output connected to the input of the scaling unit, the output of which connected to the seismic channel calibration input and to the second input of the channel switch, characterized in that, in order to increase accuracy while increasing the efficiency and accuracy of the calibration, the normalizing amplifiers and the adaptive digital notch filter are additionally introduced, and the switch output is connected to the input of the unit normalizing amplifiers, the first output of which is connected to the input of the analog-digital converter, the second output is connected to the second input of the digital recorder, the output of the analogue The digital converter is connected to the first input of the adaptive digital filter filter, to the second input of which the second output of the generator is connected, and the output is connected to the first input of the digital recorder, the output of the latter is connected to the output of the device. 2. The device according to claim 1, that the adaptive digital hedge filter contains a microprocessor, the address register is permanently stored device, random access memory, trunk transceiver, data output register, device address decoder, the input of the trunk transceiver being the first the input of the filter connected to the output of the analog-digital converter, the input of the microprocessor is the second input of the filter connected to the second output of the generator, the output of the data output register is the output of the filter; microprocessor input-output, connected to the first input of the address register and to the first input of the data output register, the same input-output connected to the outputs of the permanent storage device, random access memory and main transceiver; the second input of the address register and the first inputs of a constant memory devices and random access memory devices are connected to the address decoder code, and its five outputs are connected to the third input of the address register, the second inputs of the permanent and random access memory, the main transceiver, and the data output register figure 1 Cfffoxaa  8xoO IU Yamkp R