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Parallel Processing of Broad-Band PPM SignalsA parallel-processing algorithm and a hardware architecture to implement the algorithm have been devised for timeslot synchronization in the reception of pulse-position-modulated (PPM) optical or radio signals. As in the cases of some prior algorithms and architectures for parallel, discrete-time, digital processing of signals other than PPM, an incoming broadband signal is divided into multiple parallel narrower-band signals by means of sub-sampling and filtering. The number of parallel streams is chosen so that the frequency content of the narrower-band signals is low enough to enable processing by relatively-low speed complementary metal oxide semiconductor (CMOS) electronic circuitry. The algorithm and architecture are intended to satisfy requirements for time-varying time-slot synchronization and post-detection filtering, with correction of timing errors independent of estimation of timing errors. They are also intended to afford flexibility for dynamic reconfiguration and upgrading. The architecture is implemented in a reconfigurable CMOS processor in the form of a field-programmable gate array. The algorithm and its hardware implementation incorporate three separate time-varying filter banks for three distinct functions: correction of sub-sample timing errors, post-detection filtering, and post-detection estimation of timing errors. The design of the filter bank for correction of timing errors, the method of estimating timing errors, and the design of a feedback-loop filter are governed by a host of parameters, the most critical one, with regard to processing very broadband signals with CMOS hardware, being the number of parallel streams (equivalently, the rate-reduction parameter).
Document ID
Document Type
Other - NASA Tech Brief
Gray, Andrew (California Inst. of Tech. Pasadena, CA, United States)
Kang, Edward (California Inst. of Tech. Pasadena, CA, United States)
Lay, Norman (California Inst. of Tech. Pasadena, CA, United States)
Vilnrotter, Victor (California Inst. of Tech. Pasadena, CA, United States)
Srinivasan, Meera (California Inst. of Tech. Pasadena, CA, United States)
Lee, Clement (California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 25, 2013
Publication Date
March 1, 2010
Publication Information
Publication: NASA Tech Briefs, March 2010
Subject Category
Man/System Technology and Life Support
Report/Patent Number
Distribution Limits
Public Use Permitted.

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IDRelationTitle20100009649Analytic PrimaryNASA Tech Briefs, March 2010