SU1347045A1 - Device for measuring depth of modualtion - Google Patents

Abstract

The invention can be used in systems of automatic control and regulation with amplitude modulation and allows to increase the speed of the device. The device comprises an input stage 1, an amplifier 2, a linear detector 3, a low-pass filter 4, a peak detector 6 and the elements 8 and 9 of the comparison. To achieve this goal, it includes the generators of the reference signal 5, pulses 7 and reference frequency 12, control triggers 10 and 11, keys 13 and 14, counters 15 and 18, overflow trigger 16, transfer unit 17, counter 19 with digital indication and a button 20 Start and formed new functional connections. 1 il. U (t 021 (L w 4 O 4 OT

Description

15

The invention relates to measuring tekinke and can be used in systems of automatic control and regulation with amplitude modulation.

The purpose of the invention is to increase speed,

The drawing shows a block diagram of the proposed device. Yu

The device contains: an input stage 1, an amplifier 2, a linear detector 3, a low-pass filter 4, a reference signal generator 5, a peak detector 6, a pulse generator 7, comparison elements 8 and 9, control triggers 10 and 1, a reference frequency generator 12, keys 13 and 14, first counter 15, overflow trigger 16, transfer unit 17, second counter 18, counter 19 with diffraction indication, Start button 20, first 21 and second 22 input terminals of the device.

The device works as follows .25

The amplitude-modulated (AM) signal U (t5 is fed through the input stage 1 to amplifier 2, which serves as a scaling converter to provide the required input impedance of the device. From the output of amplifier 2, the AM signal is fed to the linear detector 3. After the detection, the pulse voltage contains a constant component proportional to the level of the carrier U, and a variable component reproducing the shape of the envelope U. The constant component after passing the low-pass filter is applied to the element 40.8 comparison, the variable component of the AM signal after passing through the peak detector b is fed to the comparison element 9. On the Start command, button 20 turns on the generator 7 pulses-45 sov. Clock pulse from the latter starts the generator 5 of the reference voltage and triggers 10 and 11, the signals of which open the keys 13 and 14 to pass the reference frequency 50 to the counters 15 and 18. By setting Impact O, the counters 15 and 18 and the overflow trigger 16 are reset, which is 20

bakes a dzukhkanal analog-digital-gg pa connected to one of the inputs of the second voltage transformer, a pro element of comparison, which differs in proportional levels of the carrier and the envelope of the AM signal into a proportional number of pulses N4 and N 5 records

Generated in. Counters 15 and 18 from the generator 12 of the reference frequency.

The analog-to-digital conversion process repeats n times until the counter 15 is filled, after which the overflow trigger 6 is triggered, which outputs a pulse to the key control triggers 10 and 11 13 and 14 to stop filling the counters 15 and 18 and the pulse to 17 the pulseN.

sa The number of pulses and recorded in the counter 18, is proportional to the envelope and. With the aid of the transfer unit, the pulses are recorded in counter 19 with a digital indication. Since the modulation depth is defined as the ratio of the maximum change in the amplitude of the envelope uU relative to 0 carrier in the absence of modulation

di"

KM

and"

that

Uh

N. o:

UM N; N -. TO.

where tig is the maximum value of the reference voltage corresponding to the maximum change in the envelope with respect to the carrier amplitude in the absence of modulation; N is the number of pulses corresponding to the reference voltage

-and,.

Then the content of 18 is equal to (Ujn) .N

counters 15 and

and.,

 to.

N7 TujlTJ N and; -

Claims (1)

those. proportional to the depth of modulation An apparatus for measuring the amplitude modulation coefficient, comprising a series-connected first input terminal of the device, an input stage, an amplifier and a linear detector, the output of which is connected to the inputs of a peak detector and a low-pass filter, the output of which is connected to one of the inputs of the first reference element, the output of peak detection e e with the fact that, in order to improve speed, a pulse generator, a reference generator signal generator, reference frequency generator, two keys, Start button, two control triggers, two counters, transfer unit, counter with digital indication and overflow trigger, the input of the pulse generator through the Start button connected to the second input terminal of the device, and the first generator output pulses are connected to the control input of the reference signal generator and the first inputs of the first and second control triggers., the second output of the pulse generator is connected to the installation inputs of the counters, the output of the reference signal generator Connected to the second inputs of the first and second comparison elements, the output of the first comparison element through a serially connected first control trigger and the first key is connected to the input of the first counter, the output of which is connected to the input of the overflow trigger, the output of the second comparison element through the serially connected second control trigger and the second key connected to the input of the second counter, the output of which is connected to the first input of the transfer unit, the second input of which is connected to the output of the overflow trigger and to the third To the inputs of the first and second control triggers, the output of the transfer unit is connected to the input of a digital indication counter, the output of the reference frequency generator is connected to the second inputs of the first and second keys.