SU1598108A1 - Frequency detector - Google Patents

Abstract

The invention relates to telecommunications. The purpose of the invention is to improve the detection accuracy by restoring the constant and low frequency components of the modulating signal. Frequency detector (BH) contains an amplifier-limiter 1, formers 2 and 3 zero crossing pulses, synchronous one-shot (CO) 4 and 5, a generator 6 reference pulses, a divider 7 pulse frequency, an inverter 8, an adder 9, a low-pass filter (LPF ) 10. Sequences of pulse length stable pulses formed in CO 4 and 5, after inverter 8, are folded in adder 9 to form a two-pole pulse signal, and LPF 10 is filtered, the output of which is the output of the BH signal. 1 il.

Description

The invention relates to telecommunications and radio engineering and can be used in receiving communications equipment and radio measuring equipment. .

The aim of the invention is to improve the detection accuracy by restoring the constant and low frequency components of the modulating signal. , .ten

FIG. 1 shows the flow chart of the proposed frequency detector; in fig. 2 - time diagrams, according to his work.

The frequency detector contains the amplifier i-limiter 1, the first and second formers 2 and 3 of the transition pulses through O, the first and second synchronous one-shot 4 and 5, the generator 6 reference pulses, divider JQ

7 pulse frequencies, an inverter 8, an adder 9 and a low-pass filter 10, the first and second shapers 2 and 3. The transition pulses through O are made on Three elements NOT 11, 25 two elements AND 12 and element OR 13, and synchronous one-shot 4 and 5 are made on the trigger 14 and the counter 15.

Frequency detector works as follows. ..

A sinusoidal frequency-modulated signal (Fig. 2a) is fed to the input of a frequency detector, transformed by a limiting amplifier 1 into a pulsed (Fig. 2b), from which the first driver. 2 pulses of transition through O form short pulses (Fig. 2c), which are tied to the time of transition of the input sinusoidal signal through O,

thirty

35

eye synchronous one-shot 5 (fig. 2 g) - by dividing the frequency of the reference pulses of the generator 6 by the divider 7 of the pulse frequency (fig. 2 d) with the division factor N and forming the output pulses of the divider by the former of 3 period pulses through O short pulses used to start the second synchronous one-shot 5 (fig. 2e) the Formers 2 and 3 of the transition pulse through O are made according to a two-channel scheme. The first channel contains serially connected first and second elements NOT 11 and element I 12, the output of which is connected to the first input of the element OR 13. The second channel contains serially connected third element NOT 11 and the second element And 12, the output of which is connected to the second input of the element OR 13 , and in each channel the second input element And 12 is connected to the input of the second and third elements NOT 11, respectively. The first and second synchronous one-shot are made according to the scheme containing trigger 14 and counter 15, the output of which is connected to the installation input to the trigger 14, the counting input of which is connected to the output of the corresponding element OR 13 of the first and second channels, and the output of the trigger 14 of each channel is connected to the input of the corresponding counter 15 pulses, the counting input of which is connected to the output of the generator 6 reference pulses.

The output pulses of the first synchronous single vibrator 4 are fed to ne

SINUSOIDALNI and ni psiyu.pplkotorye which arrive at the first time the blue input of the adder 9, "and the second input

chronic one-shot 4, to the counting input of which impulses are received from the generator 6 reference pulses, the frequency of which is N times the carrier frequency of the input signal. The first synchronous one-shot 4 generates pulses that differ in duration from each other by no more than the period of the pulse of the generator 6 of reference pulses (Fig. 2 g), the duration of the pulses generated is determined by the period of the reference pulses and the capacity of the counter 15 pulses of the first synchronous one-shot 4 , performed on the trigger 14 and the counter 15 pulses. .

Similarly, pulses of the reference carrier frequency are formed in which the impulses are output from the output of the second synchronous one-oscillator 5 through the inverter 8 (Fig. 2 h). At the output of adder 9 a total is formed

45. The signal (Fig. 2 and), which is fed to the input of the low-pass filter U, the output signal of which is the output signal of the frequency detector (Fig. 2 k) ..

0 Input signal detection by a device whose instrumental constant is eliminated by the use of digital transition drivers

55 through O, and synchronous one-vibrator allows to obtain an output demodulated signal with all spectral components, i.e. with constant

Q

five

0

five

eye synchronous one-shot 5 (fig. 2 g) - by dividing the frequency of the reference pulses of the generator 6 by the divider 7 of the pulse frequency (fig. 2 d) with the division factor N and forming the output pulses of the divider by the former of 3 period pulses through O short pulses used to start the second synchronous one-shot 5 (fig. 2e), the formers 2 and 3 of the transition pulse through O are made according to a two-channel scheme. The first channel contains serially connected first and second elements NOT 11 and element I 12, the output of which is connected to the first input of the element OR 13. The second channel contains serially connected third element NOT 11 and the second element And 12, the output of which is connected to the second input of the element OR 13 , and in each channel the second input element And 12 is connected to the input of the second and third elements NOT 11, respectively. The first and second synchronous one-shot are made according to the scheme containing trigger 14 and counter 15, the output of which is connected to the installation input to the trigger 14, the counting input of which is connected to the output of the corresponding element OR 13 of the first and second channels, and the output of the trigger 14 of each channel is connected to the input of the corresponding counter 15 pulses, the counting input of which is connected to the output of the generator 6 reference pulses.

The output pulses of the first synchronous one-shot 4 are fed to the first input of the adder 9, "and the second input

the output of the adder 9, "and the second input

which receives the pulses from the output of the second synchronous one-shot 5 through the inverter 8 (Fig. 2 h). At the output of the adder 9 a total is formed.

a signal (Fig. 2i), which is fed to the input of the Yu low-pass filter, the output of which is the output signal of the frequency detector (Fig. 2k) ..

Input signal detection by a device whose instrumental constant is eliminated by using digital transition pulse drivers

through O, and synchronous one-shot, allows to obtain an output demodulated signal with all spectral components, i.e. with constant

and low frequency components of the modulated signal spectrum.

Thus, the use of the digital method of forming a calibrated in duration HMOyj bCOB in the proposed frequency detector, applied to the inputs of the adder, improves the accuracy of detection of the frequency-modulated signal by reconstructing the constant and low-frequency components of the spectrum of the modulating signal.

Claims (1)

Invention Formula A frequency detector comprising a limiting amplifier whose input is the input of a frequency detector, an inverter, a series-connected adder and a low-pass filter whose output is an output hour five 0 This detector is distinguished by the fact that, in order to increase the detection accuracy due to the restoration of the constant and low-frequency spectral components of the spectrum of the modulating signal, the first shaper of the transition pulses through O and the first synchronous are introduced in it. one-shot, serially connected reference pulse generator, pulse frequency divider, second transducer of transition pulses through O and second synchronous single-vibrator, the output of which through an inverter is connected to the second input of the adder, the first input of which is connected to the output of the first synchronous single-vibration, and the counting inputs of the first and The second synchronous single-vibrators are connected to the output of the reference pulse generator. g-1 p p p p p p AM m g I I and I I, d e T g-1 T- | p p p p I II I I II I IIIaUUUUUIJUIJUUUU p p p p p p p p p n n n AM