METHOD FOR QUADRATURE RECEPTION OF FREQUENCY- KEYED SIGNALS WITH MINIMAL SHIFT Russian patent published in 2002 - IPC

FIELD: radio engineering. SUBSTANCE: input signal is divided into quadrature components by mixing it with reference signals spaced π/2 apart and low-frequency quadrature components are separated; low-frequency quadrature components are multiplied; result of their multiplication and output demodulated signal are used to shape half-clock-rate voltage; results of multiplication of quadrature components and half-clock-rate voltage are used to generate frequency-error voltage between signal carrier and reference signals; error voltage is used to shape reference- signals spaced π/2 apart and coinciding in frequency with carrier of frequency-keyed signals; quadrature components are differentiated; difference between quadrature components is calculated; quadrature components are summed up; difference between differentiated signals is multiplied by sum of quadrature components; half-clock-rate voltage is subtracted from result of multiplication of differentiated quadrature components by sum of quadrature components, this being followed by filtering off voltage obtained to yield demodulated output signal. EFFECT: enhanced noise immunity in receiving frequency-keyed signal with continuous phase and minimal shift. 10 dwg