A digital intermediate frequency chip in a subscriber unit for a wireless digital communication system

摘要

The DIF chip digitally synthesizes a digital intermediate frequency signal by direct digital synthesis (DDS) and modulates the digital intermediate frequency signal with the filtered input symbols to provide a modulated intermediate frequency input signal. Tuning registers 65 store phase increment data from the processor, the DDS phase accumulator 66 accumulates the data from registers 65 and provides digitized phase values which are used to generate (67) a digital IF signal, mixed in modulator 68 and filtered in noise shaper 69. IMAGE