SU415821A1 - - Google Patents

Description

one

The invention relates to communication systems and can be applied to transmit digital data.

There are devices with a Pilot-signal located in the middle of the “press and release” frequencies; they consist of a series-connected pre-amplification path, a mixer with a local oscillator tuned to the frequency of a nilot signal, a narrow-band filter and a synchronous detector, the second input of which is connected to the pre-amplification path through a broadband filter.

A disadvantage of the known device is low noise immunity.

In order to improve the noise immunity according to the invention, ia device is inserted into a manipulation transducer, which is connected between the pre-amplification path output and the broadband filter input. Moreover, the manipulation transducer is made of IB as a mixer, the second input of which is connected through the phase shifter to the output of the local oscillator, the control input of which is connected to the output of the mixer through an automatic frequency control circuit.

FIG. 1 is a block diagram of this device; in fig. 2 -signals that can be observed at various points of the device's block circuit; in fig. 3, a and Z. FM spectra are shown, corresponding to, and

"Units and" zero m (i.e., "pressing and" unwrapping).

The device contains a generator 1 baud frequency, phase shifter 2 baud frequency,

shaper 3 pulses, information code source 4, first balanced modulator 5, carrier phase shifter 6, phase manipulator 7, second balanced modulator 8, carrier generator 9, adder 10, amplifier 11

power, transmitting antenna A1, receiving antenna A2, amplifier-converter 12 high frequency, phase demodulator 13, coherent detector (mixer) 14, phase shifter 15, phase detector (mixer)

16, an unmodifiable oscillator 17 (local oscillator), a control element 18, a low-frequency filter 19, a narrow-band filter 20, a phase detector 21, a phase detector 22 that extracts information, a driver 23 pulseson,

synchronous integrator 24.

The device works as follows. Non-transfer of the information code in this device is carried out in the tact set by generator 1.

Voltage

U, ((v, Bin (f +,

 z /

r 2 where baud frequency;

T - the duration of the baud;

Ф - initial phase;

produced by the generator 1, enters the phase shifter 2, the output of which creates a voltage

f / i (About vising /,

fJl (t) vl COS t.

The resulting voltages f / i (i), Ui (t) are fed to the low-frequency inputs of the balanced modulators 5 and 8, and, in addition, the voltage Ui (t) is fed to the driver 3 of the pulses UcH (i). The sync pulses Ucj formed by shaper 3, (t) are inputted to the synchronization input of source 4 of the information code, which produces a voltage L /, i {0 of different polarity depending on the transfer of "one" and "zero." The moments of the transition of the voltage L / ,, (J) through zero, corresponding to the transitions of the information from the “one to the zero” and vice versa, coincide with the moments of the appearance of the clock pulses Licu (i).

The carrier-mounted generator 9 generates a voltage

i / o (t): 0 cos (o, + p “),

which is fed through the phase shifter 6 to the balanced modulator 5, as well as to the balanced modulator 8 via the phase shifter 6 and the phase manipulator 7, to the control input of which the voltage of the information source 4 is supplied. In this case, the high-frequency input of the balanced modulator 5 creates a voltage

Uo (i} - osin (ro),

and at the high-frequency input of the balanced modulator 8 there is a voltage

 VO cos) when transmitting Uo (t) {, "units

I-vocos () when transmitting “zero.

Balanced modulators 5, 8 multiply the input signals

Ul ((f} and t / o (0, Ui (i), respectively. The resulting balanced-modulated oscillations

Uz (t) V2 cos - / sin (oi + To)

i

AND

V2Sm COS (lfio + To)

jb

vgSin - / COS (cBoif + avg „)

a, the carrier voltage i / o (i) is also fed to the adder 10, the output of which is amplified in the power amplifier 11 and radiated to the receiving location using the transmitting antenna k.

The generated radio signal f / cCO has the form of a frequency-manialed signal with the rest of the carrier:

f / c (O vj, sin (w, g; + o) +

Q

in transmission

vc sin I cDj -f -tg And + in "units

Co. . . one

when transmitting the seam- YJ + .J «zero.

The spectra of the f / cfO radio signal are presented

in fig. 3 a, b for the "ones and" zeros of the code.

At the reception site, the radio signal comes from

antenna A2 to the amplifier-converter 12 high frequency and then to the phase demodulator 13 frequency-manipulated signals, composed of a coherent detector 14, phase shifter 15, phase detector 16, adjustable oscillator 17, control element 18, low-frequency filter 19 narrowband f | iltra 20, phase shifter 21, phase detector 22, extracting information. The generator 17 is tuned to the residual carrier of the FM signal, and the coherent detector 14 and the phase detector 16 select the quadrature components of the FM signal. At the output of the phase detector 16, a baud frequency component arises, manipulated by phase information.

,,, V sin Q in transmission “units 1 - V sin t in transmission“ zero.

 At the output of the coherent detector 14, after narrowband filtering by filter 20 and a phase shift by phase shifter 21, a voltage

on (0 VonSlnQ

The resulting voltage f / on (0 not dependent on the information, is fed to the input of the support of the phase detector 22, as well as to the shaper 3 pulses {/ sGG phase voltage voltage V (t) allocated to the phase detector 16, is fed to the detector 22 that extracts information. To improve noise immunity, the signal from phase detector 22 is fed to

a synchronized integrator 24, which is reset by pulses f / sBSO from the generator 23. The output signal t / out from the integrator 24 is shown in FIG. 2

Subject invention

Claims (2)

1. A synchronous receiver of frequency-driven signals, having in its spectrum a pilot signal located in the middle Press and release frequencies containing a series-connected pre-amplification path, a mixer with a local oscillator tuned to the pilot frequency, a narrowband filter and a synchronous detector, the second input of which is connected to the path output pre-amplification through a broadband filter, characterized in that, in order to improve noise immunity, an additional 1 manipulation converter is included between the output of the pre-amplification path and the input of the broadband filter. 2. Receiver according to claim 1, characterized in that the manipulation transducer is designed as a mixer, the second input of which is connected to the output of the local oscillator through a phase shifter, the control input of which is connected to the output of the mixer through an automatic frequency control circuit. ai OJ ..- Q OJa o  sh Shd2 0 .Z