SU1358107A2 - Apparatus for receiving frequency-manipulated signals - Google Patents

Abstract

The invention relates to radio engineering and communication, and is an improvement of the invention in the .A.862383. The purpose of the invention is to increase noise immunity in case of instability of a carrier of symbol frequencies (MF). The device contains bandpass filters (PF) 1.2 amplitude detectors 3, 4, subtraction unit 5, limiters 6.9, adder 7, -integrator 8, decisive block 10, frequency converter 11, controlled oscillator 12, additional adder 13 , phase detector 14, 15 low pass filter, phase shifter 16 (on Ti / l). One character is transmitted by the carrier frequency oJ ,, and the other is transmitted by the carrier frequency co ,. PF 1.2 tuned to the converted frequency of the corresponding symbol. The magnitude of the difference between the central frequencies of the PF 1.2, highlighted by the adder 13, d.b. constant and equal frequency deviation. The entered blocks 11-16 form an automatic frequency control system with two parallel branches, one of which includes the FS 1, and the other PF 2. When the SCF 1 is present at the device input, the auto-tuning ring supports the frequency at the inputs of the PVC 1 2, when the symbol is changed, the resonant frequency of the PF 1 is equal to the resonant frequency of the PF 2. This ensures the coincidence of the frequency deviation with the frequency difference of the PF setting 1.2, and obtaining max / s ratio at the amplitude detector inputs 3,4, not dependent on the magnitude of the instability of the carrier medium. 1 il. с ® sl 00 sl 00 hch

Description

The invention relates to radio engineering, can be used to create communication systems, and is an improvement of the invention on the main author. St. No. 862383,

The purpose of the invention is to increase the noise immunity in case of instability of the carrier symbol frequencies.

The drawing shows a structural electrical circuit of the proposed device.

The device contains bandpass filters 1 and 2, amplitude detectors m and 3 and 4, subtraction unit 5, first limiter 6, adder 7, integrator 8, second limiter 9, decisive unit 1.0, frequency converter 11, controlled oscillator 12, additional adder 13, phase detector 14, low pass filter 15 and phase shifter 16.

The device works as follows.

The signal input of the frequency converter 11 receives a frequency-manned signal

ra;, tl WjtJ

on the interval 1 ;;

one

“- ,,

U- (t) A.COS, UjtJ on the interval

where AJ, is the amplitude of the frequency-manipulator

LO signal, carrying one symbol frequency i

U), j is the carrier frequency of another symbol j Oj is the transmission time interval

single character i hj transmission time interval

another character.

In this case, it is assumed that the frequency deviation is constant.

D with 7 - ui

The second input of the frequency converter 11 receives a signal from the output of the controlled oscillator 12

where a

to

eleven

) A., rcos Wvrt, - the amplitude of the signal generator j

i) h; p is the generator frequency, depending on the control voltage.

The signal at the output of the frequency converter is

IT (r} -k A) tl na-g,, Uc.t) -K ,, .J

where K is the conversion factor.

From the output of the frequency converter 11, the signal goes to two bandpass filters 1 and 2, each of which is tuned to the converted frequency

the corresponding symbol o), nd, and; -Shug and also goes to the phase shifter 16, which introduces a delay on V2. As bandpass filters

1 and 2, single oscillator circuit or single-cavity quartz filter should be used. The magnitude of the difference of the central frequencies of the bandpass filters 1 and 2 should be

equal to the frequency deviation D. The value of the delay introduced by the phase shifter 16 for each of the symbolic converted frequencies is the same when selecting the values of the converted frequencies

much larger than the frequency deviation D. From the outputs of the bandpass filters 1 and 2, the amplitude-manipulated signals arrive at the amplitude detectors 3 and 4 and the additional adder 13,

at the output of which a frequency-manipulated signal is formed

thirty

U (t) K ,, - KiA, cos

(u), - u) ,, p) t + (/ (tJp- -U, +)

(W2-U) yr) t + V (u), r)

where U) is the resonant frequency of the bandpass filter 2;

Kj - transmission coefficient of the band-35 filters 1 and 2;

(l) is the resonant frequency of the bandpass filter 1; / Wp-w, +

+ U) j is the phase shift of the output signal of the bandpass filter 1 as a function of the detuning of the converted frequency of one symbol from the resonant frequency of the bandpass filter 1;

45 g (

+ U) J is the phase shift of the output signal of the bandpass filter 2 as a function of detuning the converted frequency of another gQ symbol from the resonant frequency of the Bandpass Filter 2. The signals from the output of the additional adder 13 and the phase shifter 16 are sent to the corresponding inputs of the phase gg detector 14, the output of which is formed constant voltage proportional to phase shifts between signals. The voltage from the output of the phase detector 14 enters.

low pass filter 15, which determines the inertia value of the feedback circuit. The output signal from the low-pass filter 15 is fed to the control input of the controlled oscillator 12.

The described system is an auto-tuning system with two parallel branches, the first branch includes a band-pass filter 1, the second branch is a band-pass filter 2. At the time interval when the symbol frequency tu is present at the device input, the auto-tuning ring works in one mode and supports the frequency at the inputs of the bandpass filters 1 and 2 is equal to the resonant frequency of the bandpass filter 1. The amplitude of the signal at the output of the bandpass filter 1 is maximum. When the symbol is changed, the frequency w, jumps by n, and the frequency control ring changes to another mode of operation, which is ensured by the coincidence of the frequency deviation with the difference between the settings of the band-pass filters 1 and 2. The signal frequency at the input of the band-pass filters 1 and i 2 becomes equal to the resonant frequency of the band-pass filter 2, which ensures the maximum amplitude of the signal at the output of the band-pass filter 2. When frequencies of Wi and tUjC are slowly changed and the frequency deviation constant D is preserved, the system consists of .Lazareva Editor V.Bugrenkova Tehred M.Hodanich Corrector M.Maksimishinets

Order 6009/57 Circulation 636 Subscription VNISHS USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

five

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the frequency tuning alternately adjusts the values of the converted symbol frequencies exactly to the resonance of the Iosov filter 1 and 2. This provides the maximum signal-to-noise ratio at the inputs of the amplitude detectors 3 and 4, independent of the magnitude of the carrier frequency frequencies, which leads to efficient sweeping noise immunity with significant frequency detuning.

Claims (1)

Invention Formula A device for receiving frequency-manipulated signals by the author. Ev, No. 862383, characterized in that, in order to improve noise immunity in case of instability of carrier symbol frequencies, a phase shifter is introduced, as well as a series-connected additional adder, a phase detector, a low-pass filter, a controlled oscillator, and a frequency converter, with bandpass filter outputs connected to the corresponding inputs of the adder, the output of the frequency converter is connected to the inputs of the bandpass filters and the phase shifter, the output of which is connected to the second input of the phase detector, the second input of the preset photoelectret frequency is input apparatus for receiving FSK signals.