DIGITAL RECEIVER FOR VARIABLE DATA RATE COMMUNICATIONS

摘要

A digital receiver (20) includes a tuner (24) and a demodulator (30) that obtains a baseband signal (36) carried in a received analog signal (22). A first sampler (46) operates at a preselected fixed asynchronous sampling rate on the baseband component to produce a first sampler output (48). A controllable digital filter (50) resamples the first sampler output to produce a filter output with a selectable resampling rate. The resampled output is time-position locked to baseband signal epochs. The resampling is processed to ascertain the bit stream of the baseband signal. The controllable filter sampling rate is automatically varied to correspond to the data rate of the baseband signal, so that the sampling rate of the first sampler need not change. Initial signal acquisition is achieved by operating the receiver as a frequency spectrum analyzer. A single signal-carrying band (66) is identified and demodulated, and a menu (72) carried on a transport layer (68) is read. This menu provides the center frequencies and bandwiths for all of the signals within an available frequency range, so that the receiver can be reconfigured for any desired signal. Changes in transmission characteristics of the signal can later be accommodated seamlessly by reading a change notice (74) transmitted in the transport layer and reconfiguring the receiver for the new transmission characteristics.