SU1617653A1 - Receiver of frequency-manipulated signal - Google Patents

Abstract

This invention relates to a radio technique. The purpose of the invention is to improve noise immunity. The receiver contains a band-pass filter 1, a limiting amplifier 2, a frequency discriminator 3, a clock synchronization block 4, a threshold block 5, a delay block 6, an And 7 block, a counter 8, an adder 9, a register 10, a DAC 11, a low-pass filter 12 , controlled by Mr. 13, a frequency converter 14, a driver of 15 pulses and a center frequency setting block 16. In this device, the change in the frequency of the input signal of the receiver will be monitored by a corresponding change in the frequency of the signal at the output of the controlled r-13, and the frequency at the input of the band-pass filter 1 will be unchanged. The goal is achieved by automatically regulating the frequency at the output of the bandpass filter 1. 1 Il.

Description

The invention relates to radio communications and can be used in apparatus for receiving discrete information transmitted by frequency-manipulated signals.

The purpose of the invention is to increase noise immunity.

The drawing shows a structural electrical diagram of the proposed receiver.

The receiver contains a band-pass filter 1, an amplifier-limiter 2, a frequency discriminator 3, a clock synchronization unit 4, a threshold unit 5, a delay unit 6, an AND element 7, a counter 8, an adder 9, a register 10, a digital-to-analog converter 11,! a low-pass filter 12, a controlled oscillator 13, a frequency converter 14, a pulse shaper 15 and a mid-frequency setting unit 16.

The receiver operates as follows.

Converter 14 converts the frequency of the input frequency-manipulated signal into an intermediate one, which is equal to; the frequency difference between the input signal of the device and the output signal of the controlled generator 13. The intermediate frequency signal passes through the bandpass filter 1 and the amplifier-limiter 2 and is fed to the frequency discriminator 3. Frequency discriminator 3 converts the input frequency-manipulated radio signal into a binary video signal. Using clock synchronization block 4, the clock frequency is extracted from the video signal, and using block 5, the input video signal is converted into a sequence of information symbols by comparing this signal with the threshold at the time of the arrival of the next clock pulse (at the time of decision). Using the counter 8, the clock pulses are counted, which, through the delay unit 6 and through the And 7 element, enter the counting input of the counter 8 if information symbols corresponding to 1 are present at the output of the threshold unit 5.

Thus, the number at the output of the counter 8 corresponds to the number of information symbols received at the time of exposure with a value of “1”. The counting time is determined by the pulse repetition period of the Exposure, which are generated by the shaper 15 by dividing the clock frequency by the appropriate number of times, determined by ¹ determined by the counter bit length '8. Using the adder 9, the number formed by the highest order of the output of the counter 8 is subtracted from the number set in the corresponding code in the middle frequency setting unit 16. The output number of the adder 9 is recorded in the register 10 and using the digital-to-analog Converter 11 is converted to a constant voltage. This voltage through the low-pass filter 12 is supplied to the control input of a controlled generator 13.

The proposed device performs automatic frequency control at the output of the band-pass filter 1. The number of positive information symbols at the output of the threshold block 5 depends on the average frequency of the signal present at the output of the band-pass filter 1, since the deviation of the central frequency of the input signal is equivalent to the corresponding threshold shift in the threshold block 5. A change in the number of positive pulses at the output of the threshold block causes a corresponding change in the number at the output of the adder 9 and n output voltage into controlled oscillator 13. The change in input signal frequency of the receiver is monitored by a corresponding change in output frequency signal controlled oscillator 13 and the frequency at the input of bandpass filter 1 is fixed.

Claims (1)

Claim A receiver of a frequency-manipulated signal, comprising a series-connected bandpass filter, an amplifier limiter; frequency discriminator® clock synchronization unit and threshold block, the second input of which is connected to the output of the frequency discriminator, the output of the threshold block is the output of the receiver, characterized in that, in order to increase noise immunity, a pulse shaper, a medium frequency setting unit and a delay unit connected in series, AND element, counter, adder, register, digital-to-analog converter, low-pass filter, controlled generator and frequency converter, the output of which is connected to the input an axial filter, the second input of the And element is connected to the output of the threshold block, the output of the clock synchronization block is connected to the input of the delay block and through a pulse former with the second inputs of the counter and register, the output of the mid-frequency setting unit is connected to the second input of the adder, the input of the frequency converter is the input of the receiver .