SU807314A1 - Discriminator of time shift of two coherent random signals - Google Patents

Description

one

The invention relates to computing and electronic automation, relates to a time shift discriminator, which is designed to detect temporal mismatch in correlation systems and can be used as a sensitive element (measuring device) in electronic automatic control systems.

Unlike correlometers, known digital recorders have a characteristic (magnitude dependence; output voltage versus magnitude: temporal mismatch of input signals), which is an odd function and a corresponding discriminator curve. When coherent voltages are applied to the inputs of the known discriminators, a zero voltage at the output (corresponding to zero discriminator characteristic) is obtained when the input signals do not match in time.

A correlation device is known, which is a sign discriminator of the time shift containing two amplifier-limiters, the outputs of which are connected to the inputs of two coincidence circuits and two anti-matching circuits, two triggers, the inputs of the first of which are connected respectively to two coincidence circuits, and the second with anti-coincidence circuits, four two-position keys, the inputs of the first two are connected respectively to the coincidence circuits, and; two others are connected to the anti-coincidence circuits, the control inputs of the first two keys n dklyucheny to the outputs of the second flip-flop, and the control inputs of the second key - to the outputs of the first trigger and generates a trigger output of the integrating circuit, the outputs of all of the first keys are connected to one input of flip-flop forming and second outputs of all - to another. The device has

0 characteristic, which is an odd function 1 ,.

However, in such a scheme, the zero discriminator characteristic corresponds to the discrepancy in time of the input signals. The known device calculates the correlation function of two input random signals according to the probability of their signs coinciding.

If for simplicity of analysis it is assumed that the input signals

are harmonic coherent oscillations with a period T, then the input voltage at the output of the discriminator (corresponding to zero of the discriminator characteristic) with a relative time shift of the input signals is equal to T / 4. In addition, the discriminator circuit is complex. In order to obtain a large steepness of the pulse fronts of the amplifier, the limiters must have a large gain factor. The gripping and holding bands of the discriminator characteristics are narrow. It is known that the type of discriminator characteristic depends on the parameters of the input signals. With harmonic coherent inputs with a period T, the known device has (theoretically) a characteristic with a capture and retention width equal to T / 2.

It is also known to use a correlation device built as a sound mismatch correlator, containing averagers, sign converters, two AND elements, the outputs of which are connected to the corresponding pigment inputs of the elements OR f2I.

. However, the known device is characterized by complexity of the design.

 The purpose of the invention is to simplify the discriminator and expand the linearity zone of the odd discriminatory characteristic,

The goal is achieved by the fact that in the time shift discriminator containing a measuring device, two averager, two character extraction units, whose inputs are the first and second discriminator inputs, the first outputs of the character are connected to the first and second elements, and the second the inputs of which are connected respectively to the second outputs of the second and first character extraction units, the output of the first and second elements are connected to the corresponding inputs of the OR element, enter The trigger, the third and fourth elements are And, the first inputs of which are connected to the output of the element IL15, and the second ones are connected respectively to the first and second outputs of the trigger, the inputs of which are connected respectively to the first output of the character block and the second output of the second character selection block, the output of the third element And is connected to the first output of the measuring device and to the input of the first averager, the output of the fourth element And is connected to the second input of the measuring device and to the input of the fourth averager,

FIG. 1 is a block diagram of a time shift discriminator; in fig. 2 - stress diagrams at various points of the circuit.

The time shifter discriminator contains mark selection blocks 1 and 2 (for example, Schmitt triggers), element AND 3 and 4, element OR 5, trigger 6, elements AND 7 and 8, measuring device 9, averagers 10 and AND, and is significant.

When two random coherent stresses are compared in time by the coincidence of their signs, four combinations of signs i (+ +) are possible — a coincidence of positive signs; (- -) coincidence of negative signs; ; (+ -} - anti-coincidence of positive signs; (- +) - anti-coincidence of negative signs.

If we mark with an arrow the sequence of occurrence of combinations of signs, for example (-), to can be read: following the coincidence should be anti-coincidence of positive signs Let the alternation of combinations of signs

(-f, -), (), ((- +) are called the direct i sequence and are denoted by-i are (-), and the interlaces (+ + -

- +), (-), (+),

(- + -) - is in reverse order and is denoted by (-).

If there is a time shift between the coherent signals and the first voltage is ahead of the second, then a direct sequence of alternations of characters is observed. If the first voltage lags behind the second, then the reverse sequence of alternations of signs is observed. In the absence of a time shift, there is an alternation of characters ((- +), which we call the zero sequence and denote (0).

The inputs of unbalanced triggers 1 and 2 receive coherent random signals, between which the relative time shift is required to be measured. Using sign converters, the input signals are clipped. Clipping The voltages at the outputs of converters 1 and 2 contain information only about changes in the signs of the input signals.

Discriminant; op time shift computes, by probability of coincidence of signs, the function

K (C). sign (&) - (I-PC)

 sign (D) P,

n

Where

(1 for d (-); sign (Д) | -1 for UI (-);

Claims (2)

11 at -1 at d (0) The definition of K (tr) can be practically implemented by logical sorting of the pulses signaling the signs of the input signals into two groups (into two channels) according to the signs of the forward and reverse sequence of alternation in each group ( each channel of pulses, in terms of time and their constant component. The discriminator works down; 5 in a skinny way. FIG. 2 shows the voltages between the outputs of the first ci and the second (At the flip-flops. If there are anti-coincidence positive signs, (+ -) of these voltages, the voltage at the output of the coincidence circuit 3 (Fig.2 in anti-coincidence negative negative signs {-. +)) the voltage at the output of the AND 4 element coincidence circuit (Fig. 2 g). The output of the element OR 5 is acted upon both by the combination of signs (+ -) and by (- +) (Fig. 2 9). OR 5 and the outputs of the voltage trigger 6 are supplied to the inputs of the elements AND 7 and 8. With the help of the trigger 6 and the elements AND 7 and 8, Optical sorting of pulses according to signs of direct and reverse sequence. Trigger b is controlled by the leading edges of positive pulses through a single input from the direct output of block 1, through the second input from the inverse output of block 2. Fig. 26 shows the voltage between the outputs of trigger 6 In the reverse sequence of alternating characters of input signals, an impulse voltage is applied at the output of an AND 7 element coincidence circuit (FIG. 2, with a direct sequence, at the output of an AND element coincidence circuit (Fig. 2). Thus, in the above formula, the value of the factor sign (L) is determined. If the pulse voltage appears at the output of the coincidence circuit 7, then this means that sign (d) -1, if at the output of the coincidence circuit of the element And 8, then sign (ui) 1. It was shown above that (t :) Rc. The accuracy of Pc can be calculated from the duration of the time intervals corresponding to the coincidence and mismatch of the input signals (Fig. 2 eq.) 1 L. t – l Lr t where T is the time interval over which averaging is performed; M is the number of intervals (pulses) of the time of the inconsistency of the characters of the input signal during time T; t, is the duration of the i-ro interval (pulse) of the mismatch of the characters of the input signals. In other words, Rc is constant; the component of the pulse voltage at the outputs of the elements 7 and 8. The selection of the constant component is carried out either by measuring device 9 or integrating integrators) 10 and 11. In FIG. 2CL shows a voltage plot between the outputs of the integrating circuits 10 and 11. The circuit contains a small number of elements. The most rational device can be performed on integrated circuits, or t} a transistors and semiconductor diodes. It is possible to create a discriminator in the form of an integrated chip in a single unit. The invention Discriminator of the time shift of two coherent random signals, containing a measuring device, two averager, two character extraction blocks, whose inputs are the first and second discriminator inputs, the first outputs of the character extraction blocks are respectively connected to the first inputs of the first and second elements And the second the inputs of which are connected respectively to the second outputs of the second and first character extraction units, the outputs of the first and second elements I are connected to the corresponding inputs element OR, characterized in that, in order to simplify the discriminator and expand the linearity zone of the odd discriminatory characteristic, the trigger, the third and fourth elements AND, the first inputs of which are connected to the output, are entered into the discriminator. element OR, and the second - connected respectively to the first and second outputs of the trigger, the inputs of which are connected respectively to the first output of the first character extraction unit and to the second output of the second sign separator, the output of the third element I is connected to the first output of the measuring device and the input of the averager, the output of the fourth element And is connected to the second output of the measuring device and to the input of the second averager. Sources of information taken into account in the examination 1. The author's certificate of the USSR 271909, cl. G06G 7/52, 1970. 2.Kurochkin S.S. Multichannel calculating systems and correlometers. M., Energie, 1972, p. 223-228. - gpc