SU1417207A1 - Demodulator of frequency-manipulated signals - Google Patents

Abstract

The invention relates to radio engineering and can be used in radio receiving devices. The purpose of the invention is to improve noise immunity. The demodulator contains a phase detector (PD) I, a low-pass filter 2, a control element 3, an ignition / equal equalizer, a first e-generator (UG) 4, a ba.mannann modulator 5, and a 6-second oscillator. The data input to the PD 1 input signal of the frequency w, the phase time AFC system, the state of bolsters I-4, implements 11 ost N) y 4 NT at the frequency We. PodstroG1ka sistem1 1 (|) Azoh AFC occurs entirely, 1 the consequence of bifurcation frequency UG 4 at the output of the ba, 1annnogo about. Mxh imtortor 5 under the influence of the i-generator 6 of the shift n. The choice of the offset frequency can be adjusted but.- Yusu capture phase-phase control. B, 1 year of symmetry of the input frequencies relative to the frequency of the UG 4 and the use of a single net phase AFC in the device achieves a complete symmetry of the signal front edges at the output of its element 3, which increases the noise immunity of the demod, 1 torus. 2 Il. S (L 5

Description

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

The purpose of the invention is to improve noise immunity.

FIG. 1 shows a structural electrical circuit for a demodulator of frequency-controlled signals; in fig. 2 is a drawing explaining his work.

The frequency-manipulated demodulator contains a phase detector 1, a low-pass filter 2, a control element 3, a controlled oscillator 4, a balanced modulator 5, and a bias generator 6.

The frequency-manipulated demodulator operates as follows.

When there is no signal at the input of the demodulator of the frequency-mapped signals, the controlled oscillator 4 generates its initial frequency w.

When a signal occurs at the input of one of the frequencies, for example, v / t (Fig. 2), a phase automatic frequency control system (PLL) consisting of phase detector 1, filter 2, low frequencies, control element 3 and controlled oscillator 4, captures it and adjusts the controlled oscillator 4 towards this frequency by the value

l-Wt, - W-yfl-WcH Wc, - WBMI,

1 De Wyr, VCM and WBM,

- the frequencies at the outputs of the controlled oscillator 4, the oscillator 6, and the balanced modulator 5 (the first of two frequencies), respectively.

When a signal with a frequency Wc2 appears at the input, an adjustment of the controlled .1 silent heater 4 to Wc takes place by the value

Iwct wyrl-WCM WCJ. -M / 6Hj.

T

The adjustment of the PLL system within the specified limits occurs due to a split frequency of the controlled oscillator 4 at the output of the balanced modulator 5 under the influence of the oscillator 6 s. This bifurcation takes place continuously, regardless of whether there is a signal at the input of the demodulator or not. The control voltage from the output of the low-pass filter 2 is the output of the demodulator of the frequency-modulated signals.

By selecting the offset frequency, you can adjust the required pickup band of the PLL and match it with the parameters of the input signal. element, which ensures high synchronization accuracy and noise immunity of demodulation.

Claims (1)

Invention Formula A frequency-manipulated demodulator containing a ring-connected phase detector, a low-pass filter, a control element, a controlled oscillator and a frequency converter, and an offset generator, the output of which is connected to the second input of the frequency converter, with a second input The phase detector and the output of the low-pass filter are respectively the input and output of the frequency modulated signal demodulator, characterized in that, in order to increase the noise immunity, the frequency converter is nen a balanced modulator.  CJ