SU726487A1 - Digital period meter - Google Patents

Description

(54) DIGITAL PERIOD MEASURING;

The invention relates to the field of radio measurements and can be used to measure the period of a noise-distorted signal, whose frequency varies within insignificant limits. Digital period meters are known, comprising a reference pulse generator, a shaping device, a time relay, a trigger, two multivibrators waiting, an OR element, AND-NOT elements, a selector, a reset device and a counter 1. A disadvantage of the known device is the difficulty of tuning the device for measuring different periods signal. The closest in technical essence to the present invention is a device comprising a first trigger, a selector, a counter, a shaper, a first scaling unit, a generator of reference pulses and a second scaling unit 2. A disadvantage of the known device is low reliability. The purpose of the invention is to increase the reliability of the device. The goal is achieved in that a device containing a series-connected first trigger, a selector and a counter, a series-connected shaper and a first counting unit, the second input of which is connected to the second input of the first trigger, as well as a generator of reference pulses, the output of which is connected to the second input of the selector and the second recalculation unit, the first input of which is connected to the output of the former, the second input is connected to the output of the selector, and the output of the second recalculation unit is connected to the second input of the counter, The elements OR are connected in series with the second trigger and the element AND, the second input of which is connected to the output of the imager, the third input of the element AND is connected to the second output of the first trigger, and the output of the element AND is connected to the first input of the nejworo trigger, while the first input of the element OR is connected to the output of the first scaling unit n with the input of the second trigger, the second input of the OR element is connected to the second input of the counter, and the output is connected to the second input of the first trigger. The drawing shows a structural electronic circuit diagram of the device.

The device includes a driver 1, scaling blocks 2 and 3, element 4 AND, element 5 OR, triggers 6 and 7, the generator 8 of the reference pulses, the selector 9 and the counter 10.

The device works as follows.

In the initial position, the flip-flops 6 and 7 are in the "O" state and the selector 9 does not transmit the pulses of the generator 8 to the input of the counter 10. The period measurement starts from the moment the pulse is applied to the "start" terminal, which then enters the single input of the trigger 6, setting it to state "1, in which high potential is present at the output of trigger 6. Since high potentials are supplied to the inputs of the element 4c of the outputs of the flip-flops 6 and 7, the first short pulse after the meter starts, formed by the shaper 1 from the input signal, flows through the element 4 to the reset input of the scaler 2, wraps it and sets it to the trigger input 7 to state "1. From this point in time, the selector 9 opens and the pulses of the generator 8 arrive at the counter 10. In addition, from the zero output of the trigger 7, a low potential is applied to the input of the element 4A, prohibiting the output pulses of the former 1 through the element 4. Short pulses generated from the output signal , come from the output of shaper 1 to the counting input of recalculated block 2 (coefficient of recalculation N)) and to the reset input of the counting block 3, embraced it; o. After the arrival of N pulses at the counting input of block 2, a pulse appears at its output, which arrives at the zero inputs of the flip-flops 6 and 7 and flips JX into the state. "ABOUT. This completes the measurement cycle. The reading of the counter 10 at the end of the measurement cycle is directly proportional to the measured signal period.

The counting unit 3 is used to detect the deposition of the pulses of the former 1, due to the failure of the amplitude of the input signal under the action of noise below the triggering level of the former 1. The conversion factor in block 3 is set so that the output pulse appears in the case when its input for a time equal to 1.5 of the average period of the input signal, the impulses of the generator 8 pulse.

In the case of absence of input signal dropout, each generated pulse from the output of the imaging unit 1, folded in the conversion unit 3, does not allow the pulse to appear at the output of this unit.

In the event of an input signal falling at the output of the scaling unit 3, a pulse appears, which zeroes the counter 10, and also goes through the element 5 OR to the zero input of the trigger 7 and sets

his state "Oh. In this case, from the zero output of the trigger 7, as well as from the single output of the trigger 6, high potentials are applied to the inputs of the element 4 I. Therefore, the first pulse after the failure (loss of the pulse at the output of the imaging unit 1)

formed by the shaper 1 from the input signal, goes through element 4 to the reset input of the conversion unit 2, wrapped it, and on the single input of the trigger 7, set it again to the state "1. The selector 9 opens again and the generator 8 pulses arrive at the counter 10, i.e. the period measurement cycle is repeated. The measurement ends when N pulses from the output of the imaging unit 1 in the absence of deposition arrive at the input of the conversion unit 2.

Claims (2)

1. USSR author's certificate number 417736, cl. G 01 R 23/10, 01.08.72. 2. USSR author's certificate number 569% 3, cl. G 01 R 23/10, 05.04.76.