SU1252952A2 - Device for performing quality control of communication channel with frequency-shift keying - Google Patents

Abstract

The invention relates to radio and is an improvement of the invention on the author. No. 653753. The accuracy of the control in the conditions of multipath propagation of signals is increased. The mixture of the frequency-controlled signal and interference goes to the modulator 1, to which the signal of the reference oscillator 8 is also fed. 13 At the output of the modulator 1 a signal with a constant frequency is generated interference components and aggregate frequency components. The latter components are suppressed by the lowpass filter 4. A useful signal arrives at sampler 2. Band-pass filters 5 and 6 separate components from the sampled signal and interference with press and release frequencies of the original signal. These components are stored in adder 7 and fed to the calculator 3 of the signal-to-interference ratio. Using the input of the high-pass filter 9, the scaling amplifier 10, the amplitude detector 1I, the subtracting element 12 and the integrator 13, the signal-to-noise ratio fluctuations due to the presence of multipath are selected. I il. (L rv

Description

one

The invention relates to radio, can be used to control the quality of communication channels in multipath signal propagation and is an improvement of the invention according to the author. No. 653753.

The purpose of the invention is to increase the accuracy of control in the conditions of multipath propagation of signals.

The drawing shows the structural electrical circuit of the device for controlling the quality of the communication channel with frequency shift keying.

The device comprises a modulator 1, a sampler 2, a calculator 3 signal-to-noise ratio. Lowpass filter 4, first 5 and second 6 bandpass filters, adder 7, reference generator 8, high pass filter 9, scaling amplifier 10, amplitude detector 11, subtraction element 12 and integrator 13. C

The device works as follows.

one

An additive mixture of the frequency-manipulated signal and noise is fed to the input of the modulator 1, the second input of which receives a signal from the reference oscillator 8. The frequency of the reference oscillator 8 is set equal to the center frequency between the press and release frequencies of the received signal. At the output of modulator 1, a signal is formed with a constant frequency (a modulated signal) equal to half the frequency of the signal shift, components of interference with frequencies equal to the difference between the frequencies of interference and the reference oscillator 8, as well as components of total frequencies. The components of the sum frequencies are suppressed by the low-pass filter A, and the useful signal is fed to the sampler 2. The sampling rate is performed at the frequency of the reference oscillator 8. With the help of band-pass filters 5 and 6, the components with press and release frequencies Signals whose amplitudes are proportional to the level of the frequency-manipulated signal in the channel. These are the composition VNIIPI Order 4632/58 Circulation 624 Subscription Prod-polygr. pr-tie, Uzhgorod, st. Project, 4

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The accumulators are added to the adder 7 and the sum goes to one of the inputs of the calculator 3 signal-to-noise ratio. To the second input of calculator 3

5 comes the total spectrum of the signal and interference from the output of the f-4 of the lower frequencies. The use of two bandpass filters 5 and 6 and adder 7 is necessary to eliminate the effect

10 Accuracy of the device operation instabilities of the frequencies of the reference oscillator 8 and the received signal. With multipath, the voltage at the output of the calculator 3 becomes

15 fluctuating, and the power of fluctuations is proportional to the degree of multipath. The variable component of this fluctuating voltage is extracted by the filter 9 of the top 20 frequencies, amplified in the scaling amplifier 10 and after being detected in the amplitude detector I1 is supplied in the form of a constant voltage

25, to one of the inputs of subtraction element 12, to the other input of which the fluctuating voltage is supplied from the output of meter 3. The integrator serves for smoothing 30 no fluctuations. The gain of the scaling amplifier 10 is selected in accordance with the desired output voltage as a function of the degree of multipath.

Claims (1)

Invention Formula A device for monitoring the quality of the communication channel with frequency manipulation by author. No. 653753, characterized in that, in order to ensure the accuracy of control under conditions of multipath propagation of signals, a series-connected high-pass filter, a mass-amplifying amplifier, an amplitude detector, a subtraction element and an integrator, whose output is the output of the device, and the other input of the element The subtraction is connected to the output of the signal-to-noise ratio reader and to the input of the high-pass filter.