Patent ID: 7016659
Filing Date: 2006-03-21
Classification: H03C,H04H

Abstract:
1. An amplitude modulation system comprising: a carrier generator providing as output an unmodulated carrier signal at a designated carrier frequency; electronic carrier switching and phase-shifting circuitry, receiving as input the unmodulated carrier signal at reference phase, made and arranged to provide two pairs of switched carrier signals: the first pair comprising a first switched carrier signal at reference phase and a second switched carrier signal having phase shifted +90 degrees nominal relative to the reference phase, and a second pair comprising a third switched carrier signal having phase shifted −90 degrees nominal relative to the reference phase and a fourth switched carrier signal at reference phase, and to sequentially select each of the two pairs alternately at a designated switching rate in a manner to (a) hold the first pair on while holding the second pair off and (b) hold the first pair off while holding the second pair on; an audio input source providing an audio source signal containing desired modulation information; a first sideband generating system comprising: a second sideband generating system comprising: a phase refinement circuit receiving as input the unmodulated carrier signal, made and arranged to enable phase adjustment over a predetermined range for proper phase relationship with the sidebands, and to thus provide as output a phase-refined unmodulated carrier signal; and a third summing circuit, receiving as a first input the first summed sideband signal, receiving as a second input the second sideband signal and receiving as a third input the phase-refined unmodulated carrier signal, made and arranged to sum and combine the three input signals as output of the amplitude modulation system including the carrier signal and two sidebands.