METHOD OF DEMODULATING PHASE MODULATED RADIO-FREQUENCY SIGNALS AND DEVICE TO THIS END Russian patent published in 2009 - IPC H03D3/26 

FIELD: physics.

SUBSTANCE: invention can be used for demodulating (DM) phase-shift keyed, as well as phase modulated (PM) signals. Phase modulated signals are demodulated without using a reference oscillation generator and a parallel oscillatory circuit, with conversion of a phase modulated signal to an amplitude-phase (AP) modulated signal using the high-frequency (HF) part of demodulation at given amplitude modulation depth of the amplitude-phase modulated signals on a high-frequency load through provision for the required values of moduli of transmission coefficients in two states of the nonlinear element (NLE). In the method and device, demodulation takes place between the source of phase modulated radio-frequency (RF) signals and a low-frequency (LF) load. Demodulation takes place using a four-terminal network (FTN), a bipolar nonlinear element, and a low-pass filter (LPF). The phase-modulated signal is converted to an amplitude-phase modulated signal. The spectrum of the amplitude-phase modulated signal is decomposed to high- and low-frequency components using the nonlinear element. Using the low-pass filter, the information low-frequency signal is separated, amplitude of which varies according to the law of variation of the phase of the phase modulated input signal. A high-frequency load is connected between the four-terminal network and the low-pass filter. The bipolar nonlinear element is connected between the signal source and the four-terminal network into a transverse circuit. The four-terminal network is made from at least three reactive impedors, parametre values of which are chosen such that, the left slope of the amplitude-frequency curve (AFC) is formed, by providing for the required value of the modulus m₂ of the transmission coefficient of the high-frequency part of demodulation in the second state of the nonlinear element, defined by one of the extreme values of the amplitude of the amplitude-phase modulated signal. To convert the phase modulated signal to an amplitude-phase modulated signal, the phase modulated signal is transmitted to the left-side slope of the amplitude-frequency curve. The low-frequency component of the amplitude-phase modulated signal is transmitted to an integrating circuit.

EFFECT: increased noise immunity of the receiver.

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