RU2500025C2 - Correlation random signal time shift meter - Google Patents

Abstract

FIELD: measurement technology.

SUBSTANCE: time shift meter includes an input analogue multiplexer, an analogue-to-digital converter, two registers, a multiplier, random access memory, an adder, an extremum seeking unit and a control unit. The meter is characterised by using only one analogue-to-digital converter for combined processing of two analogue signals, absence of delay line compensation and presence of only one adder for multibit operands.

EFFECT: design simplification and high reliability of the correlation meter.

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Description

The invention relates to specialized information extraction devices and is used to measure time shifts between random analog signals.

Known correlation meter (prototype), containing an analog-to-digital converter, a register, a multiplier, a group of accumulating adders, two demultiplexers, an extremum search unit and a control unit, the output of the register is connected to the first input of the multiplier, the output of the multiplexer is connected to the information input of the analog-to-digital converter, the output of which is connected to the information input of the first demultiplexer, the first output of which is connected to the information input of the register, the second input of the multiplier is connected to by the output of the first demultiplexer, the output of the multiplier is connected to the information input of the second demultiplexer, the outputs of which are connected to the information inputs of the accumulating adders, the outputs of which are connected to the information inputs of the extremum search unit, the output of which is the output of the meter, the information inputs of the meter are the first and second information inputs of the multiplexer, respectively whose address input is combined with the address input of the first demultiplexer and is connected to the first address the output of the control unit, the second address output of which is connected to the address input of the second demultiplexer, the first, second and third clock outputs of the control unit are connected to the clock inputs of the analog-to-digital converter, register, and accumulating adders, respectively, the zeroing inputs of accumulating adders are combined with the zeroing input of the search unit extremum and connected to the zeroing output of the control unit, the control output of which is connected to the triggering input of the extremum search block, the trigger inputs and zeroing the correlation meter are the corresponding inputs of the control unit [Pat. RU 2229157. Publ. 05/20/2004, Bull. No. 14].

The prototype meter implements the method of pair uncorrelated samples and allows you to determine the time shift between random analog signals by the position of the peak of their cross-correlation function. However, the meter turns out to be difficult to implement: the number of independent accumulator adders is equal to the number of ordinates of the inter-correlation function, which inhibits its use in situations where it is necessary to have a relatively large range of measured time shifts or high time resolution.

The technical result achieved by using the present invention is the structural simplification of the correlation meter.

The technical result is achieved by the fact that in a known correlation meter of time shifts of random signals containing a multiplexer, an analog-to-digital converter, a first register, a multiplier, an extremum search unit and a control unit, the output of the multiplexer is connected to the information input of an analog-to-digital converter, the first input of the multiplier is connected with the output of the first register, the information inputs of the meter are respectively the first and second information inputs of the multiplexer, the address input to It is connected to the first address output of the control unit, the first clock output of which is connected to the clock input of the analog-to-digital converter, the second clock output of the control unit is connected to the clock input of the first register, the control output of the control unit is connected to the trigger input of the extremum search block, the output of which is the output measuring device, according to the invention, introduced random access memory, a second register and adder, the output of the analog-to-digital Converter is connected to the information input the house of the first register and the second input of the multiplier, the output of which is connected to the first input of the adder, the output of which is connected to the information input of the second register, the output of which is connected to the information input of random access memory, the output of which is connected to the second input of the adder, the address and control input of random access memory connected to the corresponding outputs of the control unit, the third clock output of which is connected to the clock input of the second register, the information input of the Single extremum connected to the output of random access memory, and an address input coupled to the second output of the address control unit.

In addition, the technical result is achieved by the fact that the extremum search unit implements an algorithm for determining the index of an element with a maximum value from an array representing the values of the calculated ordinates of the inter-correlation function.

The invention is illustrated by functional diagrams and timing diagrams.

Figure 1 shows a functional diagram of a correlation meter of time shifts; figure 2 shows the timing diagrams explaining the measurement of relative time shifts by the method of uncorrelated pair samples; figure 3 is a functional diagram of a control unit 9 (example of execution); 4 is a timing diagram illustrating the operation of the control unit 9.

ОЗУ 5 соединены с выходами А2 и $$\overline{WR}/RD$$

соответственно, управляющий выход СO1 блока 9 соединен с запускающим входом блока 8 поиска экстремума, выход которого является информационным выходом корреляционного измерителя временных сдвигов, входами управления СО и обнуления RST которого являются соответствующие входы блока 9 управления.Functional diagram of the correlation meter (figure 1) contains a multiplexer 1, analog-to-digital converter (ADC) 2, registers 3, 7, multiplier 4, random access memory (RAM) 5, adder 6, extremum search unit 8 and control unit 9. The output of the multiplexer 1 is connected to the information input of the ADC 2, the output of which is connected to the information input of the register 3, the output of which is connected to the first input of the multiplier 4, the second input of which is connected to the output of the ADC 2, the output of the multiplier 4 is connected to the first input of the adder 6, the second input of which connected to the DO output of RAM 5, the information input DI of which is connected to the output of the register 7, the information input of which is connected to the output of the adder 6, the information input of the extremum search unit 8 is connected to the output DO of RAM 5, the address input of the block The extreme search 8 is connected to the address output A2 of the control unit 9, the address output A1 of which is connected to the address input of the multiplexer 1, the clock inputs CLK1, CLK2 and CLK3 of the control unit 9 are connected to the clock inputs of the ADC 2, register 3 and register 7, respectively, the address input A and control input $$\overline{WR}/RD$$

RAM 5 connected to the outputs A2 and $$\overline{WR}/RD$$

accordingly, the control output СО1 of block 9 is connected to the triggering input of the extremum search block 8, the output of which is the information output of the correlation time-shift meter, the inputs of the CO control and zeroing of RST of which are the corresponding inputs of the control block 9.

The timing diagrams of FIG. 2 comprise samples of signal x (f) and samples of signal y (f) delayed relative to x (f).

блока 9 является выход элемента 29 задержки, вход которого соединен с выходом элемента 28, обнуляющие входы триггеров 18, 31, счетчиков 20, 21 объединены с первым входом элемента ИЛИ 24 и служат обнуляющим входом RST блока 9 управления, выход переполнения счетчика 20 соединен со вторым входом элемента ИЛИ 24 и с входом установки в единицу триггера 31 и представляет собой запускающий выход СO1 блока 9, вторым адресным выходом А2 которого является информационный выход счетчика 21, выход элемента ИЛИ 24 соединен с обнуляющим входом триггера 17, выход триггера 31 соединен с первым входом элемента 2 И 32, выход которого соединен со вторым входом элемента 2 ИЛИ 30, второй вход элемента 2 И 32 соединен с выходом генератора 22 тактовых импульсов.The control unit 9 of FIG. 3 contains triggers 17, 18, 31, a frequency divider 19, counters 20 and 21, a clock generator 22, an AND element 23, 32, an OR element 24, 30, an element 25, 26, 27, 28 and 29 delays. The installation input to the trigger unit 17 is the trigger input of the control unit 9, the output of the trigger 17 is connected to the D-input of the trigger 18, the output of which is connected to the first input of the And 23 element, the second input of which is combined with the clock input of the trigger 18 and connected to the output of the generator 22, the inputs of the divider 19 and the delay element 25 are combined with the summing input of the counter 20 and connected to the output of the AND element 23, the summing input of the counter 21 is connected to the output of the OR element 2 30, the first input of which is connected through the delay element 27 to the output of the delay element 25 whose output is the first clock output CLK1 of the control unit 9, the second clock output CLK2 of which is the output of the delay element 26, the input of which is connected to the output of the frequency divider 19, the output of which is the first address output A1 of the block 9, whose third clock output CLK3 is the output of the element 28 delay, the input of which is connected to the output of the delay element 27, the output $$\overline{WR}/RD$$

unit 9 is the output of the delay element 29, the input of which is connected to the output of the element 28, the zeroing inputs of the triggers 18, 31, counters 20, 21 are combined with the first input of the OR element 24 and serve as the zeroing input RST of the control unit 9, the overflow output of the counter 20 is connected to the second the input of the OR element 24 and with the installation input to the trigger unit 31 and represents the trigger output CO1 of block 9, the second address output of which A2 is the information output of the counter 21, the output of the OR element 24 is connected to the zeroing input of the trigger 17, the output of the trigger 31 oedinen to the first input element 2 and 32, whose output is connected to the second input element 2 OR 30, a second input element 2, and 32 connected to the output 22 of the generator clock pulses.

блока 9 (фиг.4, з); текущий адресный код А2 (фиг.4, и) на втором адресном выходе блока 9.The timing diagrams of figure 4 contain: clock pulses CLK (figure 4, a) at the output of the generator 22, a logic level (figure 4, b) at the D-input of the trigger 18, address pulses A1 (figure 4, c) on the first address output of block 9; clock pulses CLK1 (figure 4, g) at the first clock output of block 9; clock pulses CLK2 (figure 4, d) at the second clock output of block 9; clock pulses "+1" (figure 4, e) at the summing input of the counter 21; clock pulses CLK3 (figure 4, g) at the third clock output of block 9; write / read output control pulses $$\overline{WR}/RD$$

block 9 (figure 4, h); the current address code A2 (figure 4, and) at the second address output of block 9.

The inventive correlation delay time meter is used to process centered, stationary and ergodic random processes x (f) and y (f). The meter is based on the method of measuring the correlation function by uncorrelated pair samples. The time shift τ between the signals x (t) and y (f) is determined by the position of the peak of their cross-correlation function R (τ).

The correlation meter (figure 1) works as follows. Through the input analog multiplexer 1, the signals x (t) and y (f) are received at the input of the ADC 2, while the multiplexer 1 commutes the input signals so that the leading signal x (f) is fed to the input of the ADC 2 less often than the delayed y (t) K + 1 times, as shown in FIG. But since only one ADC is involved in the circuit, when passing to samples y (f), the first sample is lost, for example, at time t _{i, the} sample y (t _i ) is lost, shown in Fig. 2 by a dashed line. Such a loss is quite acceptable, based on the fact that the described correlation meter is designed to operate under conditions of a nonzero time shift τ between the signals x (t) and y (t). In this case, there can be no correlation between the samples of signals x (t) and y (t) that appear at the same time. Thus, one sample x (t) accounts for K samples y (t) (see figure 2). Register 3 is used to record and store the samples of the signal x (t), in it each sample x (t) is stored for K clocks, which allows for this time to carry out K operations of multiplying the sample x (t) by the current samples of the signal y (t) coming from the input of the ADC 2. That is, for the indicated K cycles, forming one cycle, K products of the form will be obtained

x (t _i ) y (t _i + Δt),

where k is the reference number of the signal y (t) in the cycle, k = 1, 2, ..., K;

Δt - sampling period (ADC 2 clocking period);

t ₁ = i (K + 1) Δt, i = 0, 1, 2, ..., I. Note that the product kΔt determines the value of the artificially introduced time shift necessary to calculate the ordinates of the cross-correlation function R (τ), and the value K sets maximum shift, expressed in the number of periods Δt.

Further, at time t _{i + 1,} instead of the sample x (t _i ), the sample x (t _{i + 1} ) is entered into register 2 and the operation of generating the products of the above kind is repeated for the samples of the signal y (t _{i + 1} + kΔt), and so, cycle by cycle, during the observation interval, the product of samples necessary for the subsequent calculation of the correlation function is formed.

The calculation of the correlation function is assigned to the arithmetic unit formed by the multiplier 4, RAM 5, the adder 6 and the buffer register 7. The samples from the output of the multiplier 4 go to one of the inputs of the adder 6, to the other input of which the contents of the RAM 5 corresponding to the serial number of the product in cycle (k value). The amount thus obtained through the buffer register 7 goes to RAM 5 to change the previously located operand in the cell, the contents of which were used to obtain the real amount. It is easy to understand that if RAM 5 is forced to be reset at the beginning of the analysis, then the above summation and transfer procedure will be an implementation of the algorithm of summing up works with accumulation. In this case, the first product in the cycle is recorded in the RAM cell 5 with the address A (1), the second in the cell with the address A (2), the third in the cell with the address A (3), and so on until the last work, which is written in the cell with a zero address. Schematically, the correspondence of RAM addresses to the samples of signals involved in the formation of works is shown in FIG. 2. After the observation interval, which consists of a finite number of the above cycles, in RAM 5, K sums of the form

$$S_k={\displaystyle \sum _{i=0}^{i=I}x\left(t_i\right)y\left(t_i+k\Delta t\right)}$$

where (I + 1) is the number of samples of the signal x (t _i ) during the observation interval.

The position of the correlation peak necessary for estimating the time shift of the signals x (t) and y (t) is found by sequentially sorting the contents of the RAM cells 5 after the stage of generating the sums of the samples is completed, i.e., after the observation interval has elapsed. The detection of the maximum is assigned to the extremum search unit 8, the inputs of which are sequentially supplied with both the accumulated amounts S _k stored in RAM 5 and the addresses of the cells in which the indicated data is stored. Thus, the data arriving in RAM 5 is indexed, which makes it possible to determine its address (value K) after finding the operand with the maximum value, and, consequently, the estimate of the desired delay time τ * (k, Δt) = kΔt. At the same time, in connection with the meter’s functioning, the RAM addresses 5 repeat the values of k, except for zero. The zero address A (0) of RAM 5 corresponds to the maximum delay (see figure 2).

Unit 9 controls the operation of the correlation meter (see Fig. 3). The start of the correlation meter is carried out by applying a trigger pulse to the CO input 9, after which the block 9 begins to generate control signals according to the time diagrams presented in Fig. 4. For simplicity, the case of K = 4 is shown in the time diagrams. The principle of operation of block 9 is largely similar to the principle of operation of the control unit described in the prototype [Pat. RU 2229157. Publ. 05/20/2004, Bull. No. 14].

), необходимые для работы ОЗУ 5, являются смещенными во времени копиями тактовых импульсов CLK3, которые, в свою очередь, необходимы для тактирования регистра 7. Отсчет интервала наблюдения Т с дискретом Δt ведется счетчиком 20, коэффициент пересчета которого выбирается таким образом, чтобы с окончанием интервала наблюдения начал формироваться импульс переполнения, являющийся обнуляющим для триггера 17 и запускающим для триггера 31 и блока 8 поиска экстремума. Перевод триггера 31 в состояние высокого логического уровня на выходе приводит к разрешению прохождения тактовых импульсов на счетный вход адресного счетчика 21 по истечении времени Т, что необходимо для формирования адресного кода на этапе определения максимальной величины, находящейся в ОЗУ 5 и, разумеется, для работы блока 8 поиска экстремума.Let us briefly consider the principle of the formation of control signals. Before starting the start, the sequential logic of block 9 is reset, thus transferring it to the standby mode of the triggering pulse, in addition, it is assumed that the RAM cells 5 are also reset. With the appearance of the start-up pulse of CO arriving at the S-input of trigger 17, at the output of trigger 18, synchronously with the positive front of the next clock pulse (Fig. 4, a), a high logic level is established that allows the passage of clock pulses to the inputs of the frequency divider 19 and counters 20, 21. Since, according to the measurement algorithm, the signal x (t) is recorded in the buffer register 4 at the beginning of the cycle, the first pulse from the output of the divider 19 is used to generate the address signal directing the signal x (t) (Fig. 4, ) During the action of the top of the specified pulse, the address input of the multiplexer 1 is under the influence of a high logic level, which provides switching to the input of register 3 of the signal x (t _i ). Information in the specified register is entered on the leading edge of the first clock pulse CLK2 (figure 4, d). After the end of the action of the address pulse, the multiplexer 1 switches to the switching mode of the signal y (t), sampled in time with the pulses of the sequence CLK1 (Fig. 4, d). Since in our example k = 4, then each cycle will consist of four clock pulses. At the same time, the clock pulses from the output of the element 2I 23 through the delay elements are fed to the counting input of the counter 21 (figure 4, e), which acts as an address and controls the addressing of RAM 5. Write / read signals ( $$\overline{WR}/RD$$

), necessary for the operation of RAM 5, are time-shifted copies of CLK3 clock pulses, which, in turn, are necessary for register clock 7. The observation of the observation interval T with a discrete Δt is carried out by the counter 20, the conversion factor of which is selected so that with the end an overflow pulse began to form, which is zeroing for trigger 17 and triggering for trigger 31 and extremum search unit 8. The translation of the trigger 31 to a state of high logic level at the output leads to the resolution of the passage of clock pulses to the counting input of the address counter 21 after the time T, which is necessary for the formation of the address code at the stage of determining the maximum value located in RAM 5 and, of course, for the operation of the unit 8 extremum searches.

The time shifts introduced by the delay elements 25, 26, 27, 28, 29 provide stable unambiguous operation of the meter due to the time offset of the update information and the moments of its fixation.

The extremum search block 8 is a device that serves to select the maximum value from the array of indexed quantities S _k arriving at its input from the output of RAM 5. Index k enters block 8 at the same time as S _k from the address output A2 of block 9. The operation algorithm of block 8 there can be any, for example, the simplest algorithm for finding the maximum by successively comparing the values with each other, with the exception of the smaller of the compared ones. The implementation of block 8 on the basis of a universal microprocessor seems optimal, while the output of block 8, which is the output of the meter, depending on specific requirements, can be supplied with either the index k determining the position of the cross-correlation peak or the code τ * (k, Δt) directly.

Unlike the prototype, in which a group of accumulating adders is used, the number of which is equal to the number of calculated ordinates of the cross-correlation function, in the considered meter, all operations of summing products and accumulations are performed using one adder and RAM, which greatly simplifies both the structure of the device and its cost, and also allows you to rationally use memory resources. Moreover, the performance requirements for the only adder in the meter are the same as for the adders of the prototype.

Claims (2)

1. A correlation meter of time shifts of random signals containing a multiplexer, an analog-to-digital converter, a first register, a multiplier, an extremum search unit and a control unit, the multiplexer output is connected to the information input of an analog-to-digital converter, the first input of the multiplier is connected to the output of the first register, information the inputs of the meter are respectively the first and second information inputs of the multiplexer, the address input of which is connected to the first address output of the control unit phenomena, the first clock output of which is connected to the clock input of the analog-to-digital converter, the second clock output of the control unit is connected to the clock input of the first register, the control output of the control unit is connected to the trigger input of the extremum search block, the output of which is the output of the meter, characterized in that random access memory, a second register and an adder are introduced, the output of the analog-to-digital converter is connected to the information input of the first register and multiplies the second input Spruce, the output of which is connected to the first input of the adder, the output of which is connected to the information input of the second register, the output of which is connected to the information input of random access memory, the output of which is connected to the second input of the adder, the address and control input of random access memory are connected to the corresponding outputs of the control unit , the third clock output of which is connected to the clock input of the second register, the information input of the extremum search block is connected to the output of the operational apominayuschego device, and an address input coupled to the second output of the address control unit. 2. The correlation measuring instrument of time shifts according to claim 1, characterized in that the extremum search unit implements an algorithm for determining the index of an element with a maximum value from an array representing the values of the calculated ordinates of the inter-correlation function.

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