SU817614A1 - Digital meter of time-related position of square video pulse medium - Google Patents

Description

The invention relates to a pulse technique and can be used in digital measuring devices.

A device for fixing the middle of the time interval is known, containing a constant delay element and a falling edge shaper, connected to an input source, in which the outputs of the constant delay element and the falling edge shaper are connected to the inputs of identical delay elements with outlets, and to the input the leading edge delay element and to each of the taps in order of increasing their numbers are connected the inputs of two-input coincidence elements, with the other input of which are connected respectively to the output and retraction in order decay rates rear edge of the input signal of the delay element, and the outputs of all elements sopadeni connected to inputs of OR element whose input is the output device I.

The disadvantage of such a device is the complexity and lack of measurement accuracy.

The closest in technical essence to the present invention is a digital meter of the middle of rectangular video pulses, containing two logical elements And, two triggers, a generator of counting pulses and a counter, the output of which is connected to the input of the first trigger / output connected to the first input of the first

o the logic element and the control input — with the first input of the second logic element AND, to the other input of which a second trigger is connected, the input of which is also connected to the 5th second input of the second logic element AND to the output of the counter connected to the input.

The resolution of a known digital meter is determined by the time

B

Tr

where where T. (2 -I) is a constant time f f of the delay of the output pulse, depending on the number of bits n of the cumulative counter and the frequency f of the quantization pulses,

coming from the generator of counting pulses;

TC about the duration of the measured video pulse.

In those cases when the period of the video pulses is less than the time Tp, the measurement of the center of the video pulses is impossible 2.

The purpose of the invention is to increase the resolution of the meter.

 This goal is achieved by the fact that in a digital meter a temporary position of the center of rectangular video pulses, containing two logical elements And, two triggers, a generator and a counter, the output of which is connected to the first input of the first trigger, the output connected to the first input of the first logical element And, and the second input - with the first input of the second logic element And, to the other input of which the output of the second trigger is connected, the input of which is connected to the generator output, the output of the second element And connected to the input of the counter output of the first AND gate, introduced pulse shaper coupled with the counter output, and the generator is connected to the second input of the first logic element I.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 shows an embodiment of a meter for the case when a counting pulse generator is common to several devices; in fig. 3 time diagrams.

The digital meter consists of a generator of 1 counting pulses, logic elements 2 and 3 AND, triggers 4 and 5, a counter b and a driver 7 pulses.

The principle of measuring the center of a rectangular video pulse, explained by timing diagrams, is as follows.

A rectangular video impulse (Fig. 3a) is applied to the element T2 I. The pulses from the trigger 5, which halves the frequency of the oscillator 1 of the counting pulses, arrive here. Element 2 And performs a temporary quantization of a rectangular video pulse that goes from here to counter 6. At the end of the video pulse, its front, front, overturns trigger 4, allowing the arrival of counting pulses with double frequency through element 3 AND to cumulative counter 6 (FIG. 3b) . At the same time, the supply of pulses from element 2 is stopped.

After a time from the center of the video pulse, when the counter 6 overflows (is zeroed), a pulse forms at its output, the trailing edge

which triggers trigger 4, closing the access to the input of accumulative counter 6 with a counting pulse. At the same time, a standard impulse is formed at the output of the pulse shaper 7 (FIG. 3) corresponding to the center of the video pulse. The moment T /, corresponding to the center of the video pulse under investigation (Fig. 3a), is determined from the expression T T T, where T is the moment of output of the standard pulse from the driver 7 relative to the center of the video pulse under investigation, subtracting the delay time T, required for information processing.

In some cases, when the generator of counting pulses is common to several devices, a digital meter can be made different with a meter meter (Fig. 1) in that instead of trigger 5, which halves the frequency of generator 1 of counting pulses, a frequency multiplier 8 is introduced two (figure 2). The measurement principle remains the same.

As can be seen from the time diagrams, the constant delay time in the proposed (2 - l) i, then the device T,

known T (2 - 1) g,

Jt

decreases by a factor of 2, in which the resolution is increased. digital meter.

Claims (2)

1. USSR author's certificate No. 505969, cl. G 01 R 29/02, 1976. 2. Authors certificate of the USSR 423095, cl. G 01 R 29/00, 1975.