In-phase and quadrature detector for QAM receiver - demodulates using unregulated orthogonal carriers and controls carrier and quadrature phase offsets at baseband

摘要

The circuit recovers the communication signal transmitted, according to quadrature amplitude modulation techniques, in a receiver. The QAM signal received is demodulated with unregulated orthogonal carriers. In this way four carrier functions (v1...v4) are produces, with parameters psi, rho and sigma. These parameters are regulated in a control circuit (D1, D2, D3, LF1, LF2, LF3) so that one of the transmitted communications signals is allotted, in a single-valued fashion, to each of the demodulated signal components (As, Bs) coming from the control circuit. ADVANTAGE - Improvement in reliability, by reducing errors, using inexpensive equipment.