DEMODULATOR OF SIXTEEN-POSITION QUADRATURE-AMPLITUDE KEYED SIGNALS Russian patent published in 2005 - IPC

FIELD: radio engineering; demodulating sixteen-position quadrature-amplitude keyed signals.

SUBSTANCE: proposed demodulator, type KAM-16, has three phase detectors, two solvers, two four-position modulators, three subtracters, adder, amplifier, two multipliers, two limiters, low-pass filter, voltage-controlled generator, and four EXCLUSIVE OR gates. Amplitude difference of demodulator quadrature subchannels is detected and eliminated by subjecting signal to following procedures. Demodulator input signal is decomposed by means of recovered carrier signal into cophasal and quadrature components which are passed through first and second controlled amplifiers, supplied to solver, and tetrad of demodulated characters (A, B, C, D) is obtained at demodulator output. Four-position phase keyed signal is obtained across output of first four-position modulator by means of recovered carrier signal and two digital characters (C, D) out of tetrad of demodulated characters (A, B, C, D).

EFFECT: enhanced noise immunity.

1 cl, 5 dwg