A MODULATION SYSTEM FOR MODULATING DATA ONTO A CARRIER SIGNAL WITH OFFSETS TO COMPENSATE FOR DOPPLER EFFECT AND ALLOW A FREQUENCY SYNTHESIZING SYSTEM TO MAKE STEPS EQUAL TO CHANNEL BANDWIDTH

摘要

A method and system for modulating data onto a carrier signal in a plurality of channels, each of the channels having a channel bandwidth, can be created for use in any two-way satellite communication system or other wireless communication application where frequency hopping with or without Doppler compensation is desired. The system preferably includes a digital modulator that outputs a modulated baseband signal, an intermediate frequency modulator that receives the modulated baseband signal and outputs an intermediate frequency signal derived from the modulated baseband signal, a frequency synthesizing system that outputs a synthesized intermediate frequency signal to the intermediate frequency modulator, and a circuit (numerically controlled oscillator) connected to the digital modulator which provides a signal to the digital modulator. This signal has a frequency including an offset that allows the frequency synthesizing system and intermediate frequency modulator to make frequency steps equal to the channel bandwidth. The offset can also include a small offset that compensates for the Doppler effect.