Patent ID: 7492835

Claim:
Synchrodyning apparatus comprising: phase-splitter circuitry connected for converting to complex form a first amplitude-modulated carrier wave modulated in accordance with a succession of digital symbols and received by said phase-splitter circuitry as the input signal thereof; first synchronous detection circuitry connected for performing a first synchronous detection procedure on said first amplitude-modulated carrier wave of complex form to generate a first baseband signal having respective real and imaginary components, said first amplitude-modulated carrier wave of complex form being mixed in the first synchronous detection procedure with first local oscillations of complex form and of a frequency similar to that of said carrier wave; second synchronous detection circuitry connected for performing a second synchronous detection procedure on said first amplitude-modulated carrier wave of complex form to generate a second baseband signal having respective real and imaginary components, said first amplitude-modulated carrier wave being mixed in the second synchronous detection procedure with second local oscillations of complex form and of a frequency similar to that of said carrier wave, the respective phasings of said first local oscillations and said second local oscillations being in a quadrature relationship with each other and both being maintained substantially offset from the phasing of said carrier wave; and combining circuitry for additively combining said first baseband signal and said second baseband signal to generate a third baseband signal and for differentially combining said first baseband signal and said second baseband signal to generate a fourth baseband signal, said respective phasings of said first local oscillations and said second local oscillations being such that one of said third and said fourth baseband signals is an essentially real baseband signal and the other is an essentially imaginary baseband signal, said essentially real baseband signal reproducing said succession of digital symbols during favorable conditions of reception of said first amplitude-modulated carrier wave.