SU1290541A1 - Threshold detector - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to increase the reliability of detection of the carrier of a modulated signal normalized in amplitude. The device contains an amplitude detector 3, a comparator 4, an adder 7, a source 8 of the reference voltage of the comparator 4. A carrier-type reducing carrier (HV) 1 and a carrier filter 2, as well as a signal-to-noise ratio meter 5 and a functional converter 6 are newly introduced. Converter 6 realizes the dependence of the output voltage on the input type (x), where K (x) is a function determined by the dependence of the carrier amplitude at the output of HV 1 on the signal-to-noise ratio at its input, and Goo is the max. modulation depth caused by parasitic components at the output of HV 1. 1 sludge. (L with GcheE QD SL 4

Description

The invention relates to radio engineering and can be used in receiving devices of modulated signals.

The purpose of the invention is to increase the reliability of detection of a carrier of a modulated signal normalized in amplitude.

The drawing shows a structural electrical circuit threshold detector.

The threshold detector comprises a carrier carrier restorer 1, a carrier filter 2, an amplitude detector 3, a comparator 4, a signal-to-noise meter 5, a functional transducer 6, an adder 7.

In addition, the drawing shows the source 8 of the reference voltage of the comparator 4,

The threshold detector works as follows.

The input modulated signal having the form, for example, of a phase-shift keyed oscillation

Up (t) yl (t) / 2P 8in (); (1) n

A (t)

tl ..

one

(2)

where A (t) is the modulating signal;

R information transfer rate;

Р - signal power; f H frequency and carrier phase, mixed with noise n (t), having a power P ..., is fed to the inputs of recovery 1 and meter 5. Restored which can be fulfilled

novelty

king 1,

not, for example, in the form of multiplier

oscillates

U (t) K (q) sin (2fHft-i-4) + U (t),

where K (q) is the carrier amplitude at the output of the reducing agent 1, depending on the signal-to-noise ratio in the communication channel

U (t) -K (q) | sinl2 (f tiR) .. parasitic components with frequencies f ± iR, i - 1,2 ,,,,;

m is the parasitic modulation coefficient.

The oscillation U (t) is fed to the input of the filter 2 and further to the amplitude detector 3, the voltage from which

four

(q) (l-t-mJ-HV,

where Vj is low frequency noise;

m - the maximum allowable

modulation depth factor caused by spurious output components

reducing agent 1;

supplied to one of the inputs of the comparator 4.

The output voltage of the meter 5, proportional to the signal-to-noise ratio q, is applied to the functional converter 6, which forms the voltage

 m "K (q),

corresponding to the law of change in the level of parasitic components at the output of the reducing agent 1.

Next, the voltage V is fed to one input of the adder 7, to the second input of which the reference voltage V of the source 8 is applied,

The output voltage of the adder 7 K (q) + Vp is fed to the second input of the comparator 4,

As a result, as the level of the signal increases, the threshold value increases, compensating for the increase in level at the first input of the comparator 4 due to the parasitic components. The value of the reference voltage V is chosen so as to exceed the initial noise level Vj with a minimum signal-to-noise ratio.

Claims (1)

Invention Formula A threshold detector containing an amplitude detector connected in series and a comparator, the output of which is the output of the threshold detector, adder, output which is connected to the input of the reference voltage of the comparator, and the first input is the input of the reference voltage of the threshold detector, characterized in that in order to increase the reliability of the detection of a carrier of a modulated signal normalized in amplitude, a carrier-reducing resistor connected in series is inserted into it, the input of which is the input of the threshold detector, and the carrier filter, the output of which is connected to the input of the amplitude detector, connected in series with a meter signal-to-noise ratio, the input of which is connected to the input of the threshold detector, and a functional converter, the output of which is connected to the second input of the adder, and the functional converter realizes the dependence of the output voltage on the input type (x), where K (x) is the function determined by the dependence of the carrier amplitude at the output of the reducing agent on the signal-to-noise ratio at its input, and t is the maximum possible modulation depth factor caused by the parasitic components at the output of the carrier reducing agent.