SU558416A1 - Digital frequency demodulator - Google Patents

Description

No pulses are connected to the control input of the coarse recording unit, the first and second inputs of the differentiating circuit being the first information and control inputs of the manipulation torque extraction node, the second information input of which is the register counter, and the output of the elimination block crushing.

The drawing shows a functional diagram of the described frequency demodulator containing a reference frequency generator 1, a pulse shaper 2, connected in series to a registering counter 3 and a precise register 4, to the control input of which the clock synchronization unit 5 is connected, the second output of which is connected to the control input registering counter 3, the anchorage block 6 connected in series, the signal period counter 7, the decipher 8, the trigger 9 and the AND element 10 and the selection node of the manipulation moments 11, the output to It is costly connected to the input of the clock synchronization unit 5, the second output of which is connected to the control input of the period counter of signal 7 and the second input of the trigger 9, and the third output of the clock synchronization unit 5 is connected to the control input of the coupling unit 6, the second output of which is connected to the second the input element And 10 connected to the information input of the registering counter 3, while the output of the reference frequency generator 1 is connected to the third input of the AND element and the information inputs of the selection node of the manipulation moments 11, Pulse driver 2 is connected to the input input, the output of which is connected to the information input of the anchor block 6. Manipulation point separation unit 11 consists of differentiating circuit 12, frequency divider 13 and pulse shaping unit 14, the first output of which is connected to the control input registering counter 15, the output of which through the coarse register 16 is connected to the crushing block 17, the second pulse shaping output 14 being connected to the control input of the block second register 16, the first and second inputs of the differentiating circuit are respectively first data input and the control node isolation moments keying 1, a second information input of which is input 15 of the recording counter, and the output - the output of unit 17 eliminating fragmentation.

Digital frequency demodulator works as follows.

The frequency-manipulated signal from the output of the linear part of the receiver is fed to a pulse shaper 2, which converts a sinusoidal voltage to square impulses arriving at the second

the input of the differential circuit 12 and the information input of the anchor block 6.

The first input of the differentiating circuit 12 from the reference frequency generator 1 is accessed and pulses of the reference frequency, n times higher than the carrier frequency of the signal / o. When the rising edge of a signal pulse appears, the differentiating circuit 12 forms a short pulse tied to the pulses

reference frequency coming from the reference frequency generator 1.

From the output of the differentiating circuit 12, the pulses arrive at the frequency divider 13, which performs the selection of the K signal periods. To the output of frequency divider 13, a pulse shaping unit 14 is connected, which forms a " polling " " reset at the end of a time interval equal to K signal periods. During K periods of the signal

the information input of the registering counter 15 receives the reference frequency pulses from the reference frequency generator 1.

When a coarse recording 16 pulse arrives at the control input of the block, a survey of the number d recorded in the recording counter 15 by the end of the K signal periods is performed. This number d depends on the frequency of the signal. If the signal frequency is equal, then, where l: l / (. If the signal frequency is equal to / o-A /, then.

The coarse recording unit 16 generates at its output a signal "1, if the signal frequency / A-D /. After analyzing the number d, the register counter 15 is set to" About pulse "a reset arriving at its control input from the pulse shaping unit 14.

So the output of the block is rough

registering 16, a manipulation signal from the frequency of the radio signal arrives at the input of the crushing block 17. However, this signal has fragmentation caused by interference, since the difference in the numbers d-n is small due to the fact that the number K periods of the signal during which there was an accumulation of pulses of the reference frequency in the registering counter 15.

At the output of the crushing block 17, pulses appear that are synchronized with the moments of the signal frequency change from / O-A / k / O + A / and vice versa.

These pulses, synchronized with the points of change of the sign of manipulation, are fed to the input of the clock synchronization unit 5, which generates at a frequency equal to the rate of change of the manipulation pulses

The strobe, the polling and the pulses are reset, synchronized with the pulses of changing the sign of the signal manipulation.

The strobe pulses go to the control input of the anchor block 6. During the existence of the pulse, the strobe from the output of the anchor block 6 passes pulses to the counter of signal periods 7.

At the second output of the anchoring block b, a pulse is formed, the beginning and end of which are synchronized with the signal pulses at the information input of the anchoring block bis with a pulse "strobe" coming from the clock synchronization unit 5 to the control input of the anchorage block 6.

When the signal period counter 7 arrives N pulses of the signal, the output of the decoder 8 is the signal of the end of the count, which arrives at the input of the trigger 9 and sets it to the state "O", where from its output element And 10 receives a signal prohibiting passing through it the reference frequency pulses from the reference frequency generator 1 and the registering counter 3. The setup of trigger 9 to the state "1 occurs by pulses" is reset, coming from the output of the clock synchronization unit 5.

Thus, the recording counter 3 receives impulses of the frequency support from the reference frequency generator 1 for L “whole signal periods. The period counter of the signal 7 and the registering counter 3 are reset to the initial state by a "reset" pulse, coming from the output of the clock synchronization unit 5.

If the frequency of the signal arriving at the anchor block 6 is equal to fo + A /, then the number

Nnf

D, - / o-D /

If the frequency of the signal is equal to fo-A /, then the number of

Nnf

D, / o-A /

The number D recorded in the registering counter 3, according to the impulse “polling. from the output of the clock synchronization unit 5 is analyzed by the exact registration unit 4, from the output of which the signal "O, if

7V "/ o

/ o + A / m, 1x

and the signal "1 if

Nnfo

fo A / max

where A / max is the maximum possible change in the frequency of frequency manipulation.

Claims (2)

1. A digital frequency demodulator containing a reference frequency generator, a pulse shaper and a serially connected recording counter and an accurate recording unit, to the control input of which a clock synchronization unit is connected, the second output of which is connected to the control input of the recording counter, characterized in that in order to improve noise immunity, sequentially connected anchor block, a signal period counter, a descrambler, a trigger and an AND element and a point selection node are introduced into it tion, the output of which is connected to the clock input unit, a second output connected to the input signal unravl yuschim periods counter and the second trigger input, and the third output of the clock synchronization unit is connected to the control input of the anchor block, the second output of which is connected to the second input of the And element connected to the information input of the registering counter, and the output of the reference frequency generator is connected to the third input of the And element the information inputs of the point selection point manipulation, to the driving force the input of which is connected to the pulse shaper, the output of which is connected to the information input of the anchor block. 2. Demodulator but also. 1, characterized in that the point selection unit The manipulation consists of a serially connected differentiating circuit, a frequency divider and an imiuls forming unit, the first output of which is connected to the control input of the registering counter, the output of which through the coarse recording unit is connected to the crushing block, and the second output of the impulse shaping unit of the connection with the actuator Jup im v.hodomy block coarse registration, while The first and second inputs of the differentiating circuit are, respectively, the first information and control meters of the point of separation of the moments of manipulation, the second information input of which is the input of the registering counter, and the output is the output of the crushing block. Sources of information taken into account when examining 1. US patent number 3660771, class. 329-104, publ. 1972. 2. US patent L 3628165, cl. 329-104, publ. 1971 (prototype). / 2 r: / CZICL} -