SU1562876A2 - Apparatus for automatic adjusting of correlation meter of signals of acoustic logging - Google Patents

Abstract

The invention relates to well logging by acoustic methods. The aim of the invention is to improve the reliability of the automatic tuning system when changing the frequency of the received signal. The goal is achieved by introducing into the device an automatic setup of a frequency measurement unit including an amplifier-limiter, an analog switch, a driver of a control train, a driver of a frequency measurement window, an integrator, two comparators, two coincidence circuits, a counter with an adjustable conversion factor and a reversible counter. The signal frequency is measured on the basis of the sign multiplication and subsequent integration of one period of the input signal with a pulse equal to the period of the control signal train. When the specified detuning value is reached, one of the comparators opens (depending on its sign), which opens the corresponding coincidence circuit. As a result, pulses begin to arrive at a particular input of the reversible counter. The code from the counter output sets the frequency of the control zug. When the equal frequencies of the signal and the control train are reached, the change in the contents of the counter stops. 1 hp f-ly, 2 ill.

Description

The invention relates to the field of geophysical exploration of a well by acoustic methods and is an improvement of the device according to the author. No. 1562876.

The aim of the invention is to improve the reliability of the automatic tuning system when changing the frequency of the received signal.

Fig, 1 shows a block diagram of an additional part of the device; in FIG. 2 - voltage plots at the output of its main blocks.

The circuit contains a frequency measurement unit 1, which includes an amplifier-limiter 2, an analog switch 3, a driver 4 of the control train, a generator 5 of the frequency measurement window, an integrator 6, comparators 7 and 8, circuits 9 and 1 O, counter 11 with adjustable conversion factor and reversible counter 12.

The device works as follows.

The input signal (Fig. 2a) enters the frequency measurement unit I at the input of the amplifier-limiter 2. The rectangular pulses from its output (Fig. 26) are fed to the input of the analog switch 3 "At the moment of arrival of the useful signal, the correlation meter is produced the first entry pulse (Fig. 2c), which starts the driver 4 of the control train. The control bus of the Shaper 4 also receives the frequency code of the useful signal. On the basis of this information, it generates rectangular oscillations with a frequency 2 times higher than that of the useful signal (Fig. 2d). This signal is fed to the input of the Shaper 5 of the frequency measurement window, which produces a rectangular impulse equal to one period and located symmetrically with respect to, for example, the fifth phase of the incoming signal (Fig. 2, plot c and a). opens an analog switch 3, which will let a certain part of the input signal (Fig. 2, i) pass to the integrator 6. If the useful signal period exactly coincides with the frequency measurement window (Fig. 2, h), the voltage at the output of the integrator 6 as a result of charging yes - the bit will not change (FIG 2, plot and), the areas of positive and negative oscillations are equal to each other. If the signal period and the pulse duration do not coincide (Fig. 2, h), the equilibrium charge and discharge in the integrator is disturbed and the voltage at its output gets some increment directly proportional to the degree of mismatch. In Fig. 2, plot θ, a measurement window is presented for the case where the frequency of the control zug has become lower than twice the frequency of the signal. In this case (Fig. 2, plot L), the discharge over charge will prevail in the integrator, the voltage at its output will begin to increase in the negative direction. When it reaches a certain level, the comparator 7 will work and a coincidence circuit 9 will open. As a result, pulses from the output of counter 11 with a certain frequency will begin to flow to the subtracting input of the reversible counter 12. Its contents will begin to decrease, and

together with it, the oscillation period at the output of the driver 4 of the control zug, as well as the duration of the pulse that opens the analog key 3. This process will occur until the input signal period and the frequency measurement window duration become equal. If there is an imbalance between them in the other direction, the voltage at the output of the integrator 6 will begin to increase in a positive direction, the comparator 8 will work, the coincidence circuit 10 will open and the number of pulses recorded in the reversible counter 12 will begin to increase. In order to match the speed of the test with the frequency of the signal, the pulses to the input of the reversible counter 12 are fed through the counter 1 1 with an adjustable conversion factor, the frequency of the pulses at the output of which is determined by the code of the useful signal period. With a low signal frequency, the conversion factor in counter 1 is small and the pulses to the input of counter 12 arrive more often. As the signal frequency increases, their arrival speed decreases. Thus, it is possible in the system to avoid the overshoot mode while maintaining a high rate of testing at low frequencies. The oscillations from the output of the driver of the control zug arrive at the software device of the autotune system for the first entry, which produces pulses that exactly correspond to the first and third phases of the incoming signal (Fig. 2, plot e, g), regardless of its frequency. This achieves the stability of the autotune system over the entire frequency range of the input signal.

Claims (2)

1. Device for automatic adjustment of a correlation meter for acoustic logging signals according to the author. YE, no. -1222031, characterized in that, in order to increase the reliability of the automatic tuning system when changing the frequency of the received signal, a frequency measurement unit with three inputs and an output is additionally introduced into it, the first input connected to the first input of the amplitude discriminator, the second and the third inputs, respectively, with the fourth and third inputs of the device, and the output of the frequency measurement unit is connected to the input of the software device. 2. The device according to claim 1, characterized in that the frequency measurement unit comprises an amplifier-limiter, an analog switch and an integrator in series, as well as two comparators, two coincidence circuits, a reversible counter, a frequency measurement window generator with an adjustable frequency counter the first and second coincidence circuits, in which the second inputs are connected to the output of the counter with an adjustable conversion factor, and the outputs are connected respectively to the subtracting and summing inputs of the reversible counter, the output of which, in turn, is connected to the control inputs of the counter with an adjustable conversion factor and driver a control train whose output is connected to the input of the frequency measurement window generator and is the output of the measurement unit in an hour This and the driver of the control zug, $ one, with the output (the normalizer, with the input of the limiting amplifier for measuring the frequency, is connected to the first input of the unit, the inverting input of the first and the non-inverting input of the second comparator are connected to the sources of the threshold voltage , 20 second inputs of the comparators are connected to the integrator output, and the outputs of the comparators are connected to the inputs, respectively the analog input of the analog key, the clock input of the counter with an adjustable conversion factor is the second, and the trigger input of the Control Driver Shaper is the third input of the frequency measurement unit. The output is the same (the normalizer of the frequency measurement window is connected to the the analog input of the analog key, the clock input of the counter with an adjustable conversion factor is the second, and the trigger input of the Control Driver Shaper is the third input of the frequency measurement unit. Fig1