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US 5,710,763 AGranted
Filtered fast Fourier transmultiplexer and method
AssigneeMotorola, Inc.
InventorRobert Mark Harrison
Life of this patent
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Abstract
A filter fast Fourier transmultiplexer divides a multi-channel communication signal into single channel communication signals through a cascade of filters and mixers. The output sample rate is maintained at the input sample rate and memory requirements and computations are substantially reduced.
Claims16
A method of transmultiplexing a multi-channel information signal at a first sample rate into a plurality of selected communication channels at the first sample rate, the method comprising the steps of:
- (a) commutating the information signal to a first plurality of filters and commutating a delayed sample of the information signal to a second plurality of filters, each filter of the first plurality of filters corresponding with a filter of the second plurality of filters;
- (b) summing an output of each filter of the first plurality of filters with an output from the corresponding filter of the second plurality of filters to form a first plurality of summed outputs;
- (c) summing a scaled output of each of the second plurality of filters with an output of the corresponding filter of the first plurality of filters to form a second plurality of summed outputs;
- (d) scaling each output of the second plurality of summed outputs by a time varying value;
- (e) commutating the first plurality of summed outputs to form a first output signal at the first sample rate;
- and
- (f) commutating the scaled second plurality of summed outputs to form a second output signal at the first sample rate.
4 more elements
An apparatus for transmultiplexing a multi-channel information signal at a first sample rate into a plurality of selected communication channels at the first sample rate comprising:
- (a) means for commutating the information signal to a first plurality of filters and commutating a delayed sample of the information signal to a second plurality of filters, each filter of the first plurality of filters corresponding with a filter of the second plurality of filters;
- (b) means for summing an output of each filter of the first plurality of filters with and output from the corresponding filter of the second plurality of filters to form a first plurality of summed outputs;
- (c) means for summing a scaled output of each of the second plurality of filters with an output of the corresponding filter of the first plurality of filters to form a second plurality of summed outputs;
- (d) means for scaling each output of the second plurality of summed outputs by a time varying value;
- (e) means for commutating the first plurality of summed outputs to form a first output signal at the first sample rate;
- and
- (f) means for commutating the scaled second plurality of summed outputs to form a second output signal at the first sample rate.
4 more elements
A filtered fast Fourier transmultiplexer comprising:
- a commutator having an input and a first output and a second output, wherein the first output selectively couples a sample of a multi-channel information signal to inputs of a first plurality of filters, and the second output selectively couples a delayed sample of the multi-channel information signal to inputs of a second plurality of filters;
- the first and second plurality of filters each having an output;
- a first plurality of combiners each coupled to an output of one the first plurality of filters and to an output of a corresponding filter of the second plurality of filters, each of the first plurality of combiners having an output;
- a second plurality of combiners each coupled to an output of one of the second plurality of filters and to an output of the corresponding filter of the first plurality of filters, each of the second plurality of combiners having an output;
- a plurality of scalers each having an input coupled to an output of one of the second plurality of combiners and an output;
- a second commutator for commutating the outputs of the first plurality of filters to a first output signal at the sample rate;
- and
- a third commutator for commutating the outputs the plurality of scalers to a second output signal at the sample rate.
5 more elements
Dependencies are inferred from the claim text.