SU682904A1 - Correlometer - Google Patents

Description

when the delay between the studied processes is a priori unknown and can be in the range from very small values to very large, many times exceeding the time of measurement and calculation of one ordinate of the mutual correlation functions (in other words, within many times exceeding the averaging time, based on the accuracy of the measurement, and sometimes limited by the nonstationarity of the studied processes). In this case, all the ordinates of the mutual correlation function must be calculated for one realization due to the difficulty, and more often, the impossibility of repeating the conditions of the acoustic experiment. The increase in hardware costs in the cases considered is attributable to the following nodes of the well-known correlometer circuit: the delay unit of one signal under investigation relative to another (in 2 these are shift registers), the multiplication circuit of the instantaneous values of the delayed and non-delayed signals and the averaging scheme of the multiplication results. Moreover, the quantitative composition of these nodes grows in direct proportion to the maximum required delay time, while the averaging time, as a rule, does not depend on the actual delay between the studied signals and is often required much less than the latter.

The purpose of the present invention is to simplify the correlometer in analyzing processes, the delay time between which is longer than the averaging interval.

This goal is achieved by adding the third and fourth groups of AND elements, the group of OR elements, the group of delay elements, the NOT element, the additional decoder, and the second counter to the correrelometer described. The input of this counter is connected to the output of the first counter, and the output via an additional decoder is connected to the input of the PE element and to the first inputs of elements AND of the third group, the second inputs of which are connected to the corresponding outputs of the analog-digital converter. The output of the PE element is connected to the first inputs of elements AND of the fourth group, the second input of each of which is connected to the output of the corresponding delay register. The output of each element AND the fourth group is connected to the first input of each element OR group, the second input of each of which is connected to the output of the corresponding element AND of the third group. The output of each element of the OR group is connected to the input of the corresponding delay register. The input of each delay element of the group is connected to the output of the corresponding shaper, and the output is connected to the reset input of the corresponding averaging block.

The drawing shows the functional diagram of the correlometer.

The device contains a t-bit analog-to-digital converter 1, the input of which is connected to the output of the first signal source x (t), 2 delay registers, t-bit blocks 3 multiplying, averaging blocks 4, a multiple-input element OR 5, a pulse number counter 6 with a division factor equal to the number of registers, decoders of 7 states of counter 6, drivers of 8 pulses, generator of 9 clocks, generating three sequences of clocks of the same frequency shifted relative to each other in time, and two - first and

the second group of elements are 10 and 11, each of which contains n individual elements I. Each of the n multiplication blocks 3 is connected by the first inputs to the output of the second signal source y (t), the second inputs to the outputs of the A-th bits of all registers 2 and the output to the input of the element And 10, the control input of which is connected to the output 12 of the clock generator 9, on which the first sequence of clock pulses is generated. The output of the 10th element And 10 is connected to the input of the / r-th unit 4 of averaging, the output of which is connected to the input of the second element And 11 of the second group, the control input of which through the jfe-th driver of 8 pulses is connected to the output of the decoder 7th the state of the ring counter 6. The input of the latter is connected to the output 13 of the generator 9 clock pulses,

a second clock sequence is generated. Output 14 of the third sequence of clock pulses of the generator is connected to the clock inputs of registers 2 and analog-digital

Converter 1. The outputs of the second-order AI elements are connected to the inputs of the l-input element OR 5, the output of which is the output of the correlometer. The correlometer described is different from

known that it contains an additional; slant counter 15, a decoder 16 of the zero state of this counter, a NOT element 17, n delay elements 18, a group of two-input elements OR 19 and two groups

additional elements And 20 and 21. Each of them contains on m separate elements I. The input of the additional counter 15 is connected to the output of the ring counter 6. The output of the decoder 16 is the zero state of the additional counter 15 connected to the control inputs of the elements And 20 of the third group directly, and To the control inputs of the AND 21 elements of the fourth group are through the NOT element 17. The inputs of the AND 20 elements are connected to the analog-digital converter 1 with the same outputs, and the outputs to the first inputs of the two-input elements OR 19, whose outputs are are connected to the inputs of the corresponding registers 2. The second inputs of the two-input elements OR 19 are connected to the outputs of the same-named elements AND 21, whose inputs are connected to the outputs of the corresponding registers 2. The input of the setting of About-th block of averaging 4 through the 10th delay element 18 and fe-th pulse generator 8 is connected to the decoder of the 7th state of the ring counter b.

The correlometer works as follows. The first of the studied signals x (t) is fed to the input of the analog-digital converter 1. At the time (in the considered example, time i) the clock pulse from the output 14 of the generator 9 is fed to its control input, the signal is converted into the corresponding number of t-bit binary code. This number, represented by pulses (1-presence, O - no pulse), is fed to m registers 2, each of which contains r-flip-flops. Registers, as in prototype 2, perform the role of a digital delay line. But unlike the prototype, the number of triggers in each register is not determined by the required delay time, but by the required averaging time. With the appearance of each new shifting pulse at the output 14, the unit advances into the neighboring trigger and at the output of the latter a pulse arises. Pulses that represent a number in binary code, which is determined by the states of flip-flops of the same number (for example, k in all registers, are sent to block 3 multiplying the same number (in this example, number Zy). The second signal under test (O- At the output of the multiplier of the multiplication unit, the signal A /, is proportional to the partial product L /, x (t-kTo) y (fi) -To is the period of the following pulses. This signal is synchronous with the clock pulses produced at the output 12 of generator 9, transmitted through fe-th element 10 on the fe-th averaging block 4k. The clock pulses generated at the output 12 of the generator 9 are delayed relative to the pulses generated at the output 14 for the time interval Af. Therefore, in the considered example, the signal AJ will go to the -th block Averaging 4fe at the moment of time (fi-fAO, when all transients associated with the multiplications of the instantaneous values of the signals under study are already completed. Averaging synchronously with the appearance of pulses at the output of the formers of 8 pulses (in the considered example, k-TOTO former) post are fed to the output of the correlometer, and synchronously with the occurrence of pulses at the output of delay elements 18 (in this example, k-Tbtw delay element), averaging blocks 4 are zeroed. The pulses at the output of the formers 8 appear synchronously with the change in the state of the counter 6. The clock pulses generated at the output 13 of the generator 9 are fed to the input of the counter 6 with a time delay of 2Af relative to the pulses at the output 14. Thus adding the nth multiplication result

L, (). U (Oh

to the contents of the ft-block averaging with the moment of issuance of the result of averaging at the output of the correlometer.

The commencement of the calculation of the cross-correlation function in the described correlometer coincides with the time moment to when the output of the generator 13 9 generates the first clock pulse, synchronously with which the counters 6 and 15 are updated.

During the generation of the following n clock pulses, the And 20 elements are open and the And 21 elements are closed, because during this time an output potential is produced at the output of the decryptor 16, and an inhibitory potential at the output of the element 17.

Thus, in the described correlometer, during the generation of the first α-contact pulses, the registers 2 are filled with instantaneous implementation values x (t), the number of which is equal to the required averaging time.

Starting from the moment of time, the states of the elements And 20 and 21 change to opposite and instantaneous values of the realization x (f accumulated by this moment in registers 2 will circulate in the latter with a period equal to "That, along the chain: registers 2 are elements AND 21-elements OR 19 - registers 2.

Let us consider the distinctive features of the work of the proposed correlometer using the example of that channel. From the time (tn + kTa (when the instantaneous value of the signal x (t), measured in converter 1, reaches fe-th regigy of registers 2) until the time (go + To + pTo) in -th block 4 averaging accumulates the sum of private works of the form x {t-kTo -t / (t) at the moment of time (. -nTo. when the counter b enters the state (k) and at the output of the decoder 7 of the k-state of the counter b, the pulse, the result of averaging or fe - the ordinate of the measured FUNCTION /.T7, (feTo) will be received at the output of the correlometer. At the moment of time (o - GOCH-fnTn + AI at the output of the fe-th delay element 18 a pulse, synchronously with which the fe-th averaging unit 4 is zeroed, and in the latter begins the accumulation cycle of a result proportional to (n4-k) - the row ordinate of the measured function, the value of which is Rr ,, {kTn + nT (, at the output of the correlometer at the time

f. + kT, + 2nT ,.

If the capacity of the counter 15 is equal to N, then at the output of the k-Toro element 11 at the moment of time

4 + kT, + пГ „, 4 + kT, + 2пГо, ... 4 + kT, + (N- 1}„ Т ,, f, + АГо +

the values of the measured cross-correlation function appear

 (kT ,, R, y (KG о + riT,.:. R, y kT, + + (TV - 2) ПГ „1, / ,, Go + (Л - t) / гГ„ 1,

which through the element OR 5 arrive at the output of the correlometer.

From a review of the operation of the described correlometer, it can be seen that when it is built to measure the cross-correlation function, the argument of which can take values from 0 to /// gO, and the required averaging time equal to 770, triggers are required in registers, multiplication schemes and averaging schemes L times less than in the prototype.

Claims (2)

1. Gribanov Yu. I., Veselova G. P., Andreev V. N. Automatic digital correlators. M., “Energie, 1971, p. 148-149. 2. Mirsky G. Ya. Instrumental determination of the characteristics of random processes, M., "Energia, 1972, p / 132-134,