SU960652A1 - Frequency meter - Google Patents

Description

The invention relates to measuring and computing technology and can be used in digital information-measuring systems comprising a mini-computer for processing signals of frequency sensors.

A digital frequency meter is known, containing a reference frequency generator, pulse shapers of the measured and reference frequencies, an element of coincidence, and two counters, in which the counters are filled during the time between two coincidences of measurement pulses e eI and this frequency slope C1.

A disadvantage of the known device is the long waiting time of the first match when measuring low frequencies.

The closest in technical essence to the invention is a digital frequency meter, containing a reference frequency pulse shaper, the output of which is connected to the first input of the coincidence element and with the even input of the first counter, a measured frequency pulse shaper, the output of which is connected to the second input of the coincidence element and the first entry of the first key.

the output of which is connected to the counting input of the second counter 2.

A disadvantage of the known device is the large measurement time at low frequencies, since the measurement time is the sum of the time period between two matches and the waiting time of the first match.

ten

The purpose of the invention is to increase the speed of the device.

This goal is achieved by the fact that in a frequency meter containing a reference frequency driver, the output

15 which is connected to the first entrance. the element of coincidence and with the counting input of the first counter, the pulse shaper of the measured frequency, the output of which is connected to the second input

20 and the first input of the first key, the output of which is connected to the counting input of the second counter, are connected in series the first trigger and the reference frequency generator, in series the second trigger and the second key and in series the one-shot and the inverter, the output of which is connected to entrances

30 sets the first and second zeros

counters, while the one-shot output is connected to the single input of the second trigger, the zero input of which is connected to the zero input of the first trigger and to the output of the coincidence element, the second input of which is connected to the single input of the first trigger, the output of which is connected to the second input of the first key, and the output the pulse generator of the reference frequency is connected to Bhojt; oM of the pulse frequency generator of the reference frequency,

The drawing shows the block diagram of the proposed frequency meter.

The frequency meter contains a reference oscillator 1, a shaper 2 pulses of the reference frequency, a shaper 3 pulses of the measured frequency, counters 4 and 5, a coincidence element b, keys 7 and 8, triggers 9 and 10, a single vibrator 11 and an inverter 12.

In the initial state, the reference generator and the key 7 are blocked by a logic zero signal from the output of the trigger 9, and the counters are not filled. A logic zero occurs at the input of the one-shot driver, which is the control input. The formers 2 and 3 are designed to form from the measured f and the reference fe of the frequencies of positive pulses of duration J and with a repetition period TX and Td. The outputs of the formers are connected to the inputs of the coincidence element, the output of which in the input state is a logical unit, which is fed to the inputs for setting the zeros of the flip-flops 9 and 10. Before the measurement starts, the measured frequency is supplied to the device input. The outputs of the counters and 5 are connected to the mini-computer data buses, and the counters are accessed as memory cells.

The operation of the device is as follows.

From the Iini-EBM processor, a request signal arrives at the input of the one-shot 11, and by a logical difference of 0-1 at the input of the one-shot 11, it generates a short negative pulse, which through the inverter 12 performs a reset to the zero states of counters 4 and 5 and simultaneously sets to one state trigger 10. Further, the presence of a signal on the input of the one-shot 11 is indifferent. A single signal from the output of the trigger 10 enters the key 8 and opens it. The first pulse of the measured frequency through the switch 8 changes the state of the trigger 9 from zero to one. In this case, the lock is removed from the generator 1 and the key 7. From this moment, the formation of the first period of the reference frequency begins and the simultaneous filling of the counters 4 and 5. The filling of the counters continues until the pulses coincide at the inputs of the matching element.

measured and reference frequencies. After the element at the output of the element appears, a short negative pulse appears, which is fed to the input of the installation of the zeros of the flip-flops 9 and 10, changing their state from single to zero. This completes the measurement process. The processing of the result is then carried out in a mini-computer according to the following relation

N,

: i)

 f

f ,.

X

N

where Ny is the code tilted during the measurement in counter 5; 3 oDg accumulated in the counter 4 for the same period of time.

The measurement time is determined by the value

 Th-Te

(2)

mzm 2g

Tzem

the measurement time, calculated from the beginning of the arrival of the polling pulse to the input of the one-shot to the output of the measurement result to the processor of the mini-computer. Relative measurement error is time equal to

c / fx,

(h;

Introduction to the device of the generator 1, the one-shot 11, the inverter 12 and the flip-flops 9 and 10 that control

unlocking the oscillator 1 by the first pulse of the measured frequency, reduces the waiting time for the first match in comparison with the known one from the time period between

by two matches, amounting to hundreds of periods of the measured frequency, up to the time of one period of the measured frequency.

Claims (2)

1. Authors certificate of the USSR 409149, cl. G 01 R 23/02, 1973. 2. USSR author's certificate number 56619 5, cl. S 01 ft 23/02, 1977. vmd Login Control