System and method for direct signal down-conversion and decimation
AssigneeThe Boeing Company
InventorGary A. Ray
Life of this patent
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Abstract
Systems and methods for direct signal down-conversion and decimation in a digital receiver. The digital receiver produces a decimated passband version of the signal without the problems associated with use of digital mixers. The digital receiver includes a passband-to-passband decimator/down-converter that implements an algorithm which takes the signal band (frequency and bandwidth or lower and upper frequencies) where a signal is present and produces a decimation rate and phase for use by a low-pass mixer-free down-conversion. The digital receiver technology may be efficiently implemented on a digital signal processor or field-programmable gate array.
Claims20
A method for decimating and down-converting passband signals comprising:
- (a) transducing electromagnetic radiation carrying a repetitive signal into an analog electrical passband signal;
- (b) converting the analog electrical passband signal into passband signal samples at a sampling rate;
- (c) estimating a center frequency and a bandwidth of the passband signal;
- (d) calculating a decimation ratio and a channel index based on estimated center frequency and estimated bandwidth;
- and
- (e) decimating and down-converting the passband signal samples to a sample rate which is less than the sampling rate based on the decimation ratio and channel index.
Passband-to-passband decimation/down-conversion circuitry comprising:
- circuitry for performing an algorithm that converts an estimated signal center frequency fC and an estimated signal bandwidth b to a decimation ratio L and a channel index k;
- and
- a polyphase decimator/down-converter which is connected to receive the decimation ratio L and channel index k and configured to decimate the passband samples having a sample rate fS by a factor of L and then down-convert an original passband frequency to a lower passband frequency.
A signal processing system comprising:
- a sensor configured to transduce electromagnetic radiation carrying a repetitive signal into an analog electrical signal;
- an analog-to-digital converter configured to convert the analog electrical signal into signal samples;
- a cueing system connected to receive the signal samples and configured to process the signal samples to generate digital data representing an estimated signal center frequency fC and an estimated bandwidth b;
- and
- a plurality of signal separation and tracking channel comprising:
- circuitry for performing an algorithm that converts estimated signal center frequency fC and estimated signal bandwidth b to a decimation ratio L and a channel index k;
- and
- a polyphase decimator/down-converter which is connected to receive decimation ratio L and channel index k and configured to decimate the passband samples having a sample rate fS by a factor of L and then down-convert an original passband frequency to a lower passband frequency.
Dependencies are inferred from the claim text.