Patent ID: 7039122

Claim:
A method of combining a plurality of digital signals to form a composite signal for transmission, wherein individual ones of the digitals signals comprise a stream of signal values, comprising: (a) modulating the phase and amplitude of a first component of a carrier signal by controlling both a state of a first phase modulator and a state of a first variable attenuator in accordance with values of the digital signals being combined in the composite signal, such that an attenuation level of the first variable attenuator is selected as function of a combination of the values of the digital signals; (b) modulating the phase and amplitude of a second component of the carrier signal by controlling both a state of a second phase modulator and a state of a second variable attenuator in accordance with values of the digital signals being combined in the composite signal, such that an attenuation level of the second variable attenuator is selected as function of a combination of the values of the digital signals; and (c) combining the first and second components of the carrier signal to form the composite signal.