Patent ID: 6310910
Filing Date: 2001-10-30
Classification: H04B

Abstract:
A modem for receiving a high frequency asynchronous data burst that is preceded by a unique word, the modem including a receiver that comprises:a down converter that shifts the frequency of a received asynchronous data burst;an analog to digital converter that samples the frequency shifted data burst;a demultiplexer that sequentially applies the samples to one of a plurality of channels each of which processes a portion of the asynchronous data burst in a frequency sub-band, each of the channels including:a filter and fast Fourier transformer that converts data received from the demultiplexer into data that has frequency components within one of the sub-bands;a unique word sub-band filter and a data sub-band filter that are selectively enabled in the channel to filter the data in the sub-band, wherein the unique word sub-band filter is matched to the unique word that precedes the data burst;an inverse fast Fourier transformer and filter that convert the filtered sub-band data to full spectrum filtered dataa multiplexer that combines the data from the inverse fast Fourier transformer and filters of the plurality of channels to produce a filtered data burst; anda comparator that correlates the filtered data burst with the unique word, the comparator enabling the data sub-band filters in the channels when the filtered data burst correlates to the unique word.