Patent ID: 6415002
Filing Date: 2002-07-02
Classification: H03C,H04L

Abstract:
A baseband signal modulator for providing a phase and amplitude modulated carrier signal, said signal modulator comprising:first and second phase modulators each arranged to receive a common reference signal and to derive therefrom a carrier signal frequency, and each arranged to receive a respective pair of phase-encoded data signals so as to provide respective first and second phase-encoded carrier signals derived from the respective pair of phase-encoded data signals and said carrier signal frequency, and circuit means coupled to said phase modulators and arranged to sum said first and second phase-encoded carrier signals to provide the phase and amplitude modulated carrier signal, wherein each said phase modulator comprises a respective phase locked loop incorporating an oscillator locked via the common reference signal to the carrier signal frequency, and a phase adder incorporated with the oscillator in the phase locked loop and having a first input for receiving the carrier frequency signal and having second and third inputs for receiving the respective pair of phase-encoded data signals.