SU789855A1 - Apparatus for time coupling to extremum values of harmonic signal - Google Patents

Description

one

The invention relates to a radio measuring technique and can be used in wide-range measurements of the temporal characteristics of harmonic signals and, in particular, phase meters, IGVZ, frequency meters and periodometers.

Known measures of the temporal characteristics of the harmonic signals, containing amplifiers, limiters, threshold elements, generators and counters lJ.

A disadvantage of the known devices is low measurement accuracy.

Of the known devices, the closest to the proposed technical essence is a device comprising a generator, an amplifier, a limiter, a register, a comparison element, codes, a counter, a start element and a controlled trigger 2.

The disadvantage of the device is low measurement accuracy.

The purpose of the invention is to improve the accuracy to the extreme values of the sinusoidal signal.

This goal is achieved by the fact that, in a time-bound device, to extreme values of a harmonic signal, comprising an amplifier, a limiter, a generator, a control trigger, serially connected start element, a register, and a code comparison element, as well as

5, the outputs of which are connected to the second inputs of the comparison code element, a pulse distributor, a trigger, an OR element, a first and a second match elements are entered,

10 counting trigger, serially connected additional register and additional code comparison element, serially connected switch, key, driver, and

5 a delay unit, the output of which is connected to the first input of the pulse counter, the second input — of which is connected to the third input of the code comparison element, to the second input

20 of the additional code comparison element and with the first output of the pulse distributor, the second output of the latter is connected to the second key input, to the first inputs of the first and second match elements, to the first switch input, to the first output of the counting trigger and to the first output of the additional code comparison element, the second the output of which is connected to the first input of the trigger and the first input of the OR element, the second input of the latter is connected to the second input of the trigger and to the output of the code comparison element, while the Bi-opofl output of the counting trigger gera is connected to the fourth input of the code comparison element, with the second input of the switch, and with the second input of the second matching element, the third input of which is connected to the second input of the first matching element, to the input of the counting trigger, and the output of the controlled trigger with the output of the driver, the second input of the controlled trigger is connected to the output of the OR element, the outputs of the amplifier limiter are connected to the third and fourth inputs of the switch, the output of the first element of the match is connected to the second in the register, the third input of which is connected to the first inputs of the additional register, the second input of the latter is connected to the output of the start element, the output of the second coincidence element is connected to the third input of the additional register, and the output of the generator is connected to the input of the pulse distributor.

FIG. 1 shows a block diagram of a device for time reference to extreme values of a harmonic signal; 2, time diagrams of his work.

The device of temporary assignment to the extreme values of the harmonic signal contains a generator 1, a distributor 2 pulses, a counter 3, registers 4 and 5, and elements b and 7 of the code comparison, trigger 8, element 9 OR, limit amplifier 10, switch 11 key 12, driver 13 / delay element 14, control trigger 15, counting trigger 16, elements 17 and 18 coincident, and start element 19.

The device works as follows.

Consider the operation of the device when acting on the input of the amplifier limiting a pure sinusoidal signal without noise. At the same time, the outputs of the amplifier-limiter 10 have square-wave pulses (Fig. 2a, the fronts of which are tied to the zero-transitions of the signal under study. Switch 11, controlled by the counting trigger 16, provides alternate connection of signals from the direct or inverse outputs of the amplifier limiter 10 key 12. The second input of this key receives a sequence of high frequency pulses from the output of the pulse distributor 2 (Fig. 2c), used to reset counter 3 to the zero state and record information from the counter ka 3 to registers 4 and 5. Impulse at the exit of key 12

(Fig. 2 d) takes place under the action of a positive half-wave signal at the output of the switch 11. It is standardized in terms of duration and amplitude by the driver 13 and arrives. to the input of setting zero of the control trigger 15 and, through delay element 14, to reset the counter 3. The delay time of the reset pulse (Fig. 2g) should be sufficient to switch the control trigger 15 to the zero state (Fig. 2e), prohibiting the recording of information from the counter into memory registers. At the same time, the counting trigger 16 is switched (Fig. 2h), connecting the switch 12 to the opposite output of the amplifier-limiter 10, on which a negative half-wave signal is currently acting, prohibiting the formation of reset pulses. At the same time, the counter registers pulses from the second output of the distributor 2 pulses shifted in relation to the recording impulses for the period of the frequency of generator 1. Before starting work, the memory register 19 is preset by setting the memory registers to a number not exceeding half the period of the higher frequency input signal. If the current counter code coincides with the initial code of the memory registers at the output of one of the elements 6 and 7 of the code comparison (in

- depending on the state of the counting trigger 16), a transfer pulse (Fig. 2i, k) appears, which, through element 9 OR, sets the control trigger 15 to state 1, allowing the write pulses to pass through one of the elements 17 and 18 corresponding memory register. The recording of information from the counter into the register is carried out with a reduced weight. With

5, by changing the polarity of the signal at the output of the switch 11, the recording of information into the memory register is stopped, the counter is reset, and the forward and inverse outputs are switched.

Q amplifier-limiter. As a result, a number equal to half the duration of one of the half-waves of the output signal of the limiter amplifier appears in the memory register. Similarly, during the next half period of the signal, the second memory register will write a number equal to half the duration of the second half-wave of the output signal of the amplifier-limiter. In the next period, the signal at the output of elements 6 and 7 of the code comparison will generate transfer pulses corresponding to the time midpoints half-wavelength of the output signal of the usi5 limiter or otherwise - tied to the extreme values of the input signal (without taking into account the inertia of the amplifier-limiter). These pulses control the trigger 8, which forms a signal of the square wave type, which is out of phase with respect to the input signal by 90 ° (Fig. 2n). At the same time, in each signal period, the information recorded in the memory registers is updated, so

that the temporal position of the coupling pulses is determined by the measured values of the duration of the corresponding half-waves in the previous period of the signal. The device automatically enters the settling mode, starting with the second signal period after the start time.

The required volume of the counter is determined by the lower frequency of the working range / A F, where fp is the generator frequency. To reduce the volume of the reader, it is possible to lower the frequency f in the low frequency region. Its minimum possible value is limited by the permissible error of the discrete transformation.

FIG. 2 m, n are temporary diagrams 1y, illustrating the operation of the device in the presence of broadband noise. When a mixture of sinal and noise passes through the limiting amplifier, false zero transitions appear (Fig. 2m), the number of which increases with a decrease in the signal-to-noise ratio and the signal frequency-to-noise ratio. The greatest likelihood and, accordingly, the longest residence time of the signal and noise mixture is above (below) the zero level (occur in the region of extreme values of the signal. With large signal-to-noise ratios at this time, it significantly exceeds the duration of C emissions. In the steady state in registers 4 and 5, codes corresponding to half the duration of intervals C are recorded in each signal period. When they coincide with current counter codes 3, the pulses connected to the middle of the signals are taken from the outputs of elements b and 7 of the code comparison. eagles (-. The temporal position of these pulses, as well as the fronts of the meander at the output of the trigger 8 (fig.2n in the mathematical expectation coincides with the extreme values of the input sinusoidal signal. It does not change when the signal-to-noise ratio changes and the zero line gains organichitel.

When lowering the signal-to-noise ratio the difference; in the durations of the intervals Cf, the emissions (pauses) C decrease and, under certain conditions, become difficult to distinguish.

In this case, both signal skipping and false triggering are possible.

roystva However, the likelihood of false positives, i.e. the formation of two or more pulses of reference to one of the extreme values of the signal for the period, in this device is much smaller, since after the first operation the signal polarity switches. In this case, the counter 3 is filled only during a short burst following the moment of switching, which does not cause

0 secondary actuation of the element 7 comparison codes.

Practically, in the proposed device, the formation of the coupling pulses is carried out by digital

5 signal processing based on the analysis of the duration of the emissions and pauses of the mixture of signal and noise.

The introduction of new elements and connections makes it possible to increase the noise immunity of the temporary binding device to the extreme values of the harmonic signal by about 2 times due to a significant decrease in the probability of false alarms.

. The presence of pulses of coupling to both extreme values of the signal, the temporary position of which practically does not depend on the zero line departures and the signal-to-noise ratio, improves the measurement accuracy (random

0 medium to vadraticheskaya ska error decreases in t / 2 times), as well as the speed (especially at low and low frequencies), expands the possibilities of using this device in measurement technology (for example, as a wideband quadrature device).

Claims (2)

1. USSR author's certificate No. 311214, cl. G 01 R 25/00, 1969. 2. USSR author's certificate number 573772, cl. G 01 R 25/00, 1976. Zl iJJJj I I I I I I I I I I I I 11 I.  Jif i-ei- g -r // JlCLTZlZiri IL