Coherent Multiple Hypotheses Detection and Measurement for Radio Navigation

B. Shayevits, M. Tocker, D. Rosenfeld

Abstract:	Coherent multiple hypotheses processing is a coherent integration, detection and measurement method of radio signals comprised of two modulations. This article describes the Fast Coherent Multiple Hypotheses (FCMH) method for highly efficient processing of coherent multiple hypotheses. The modulation of the signal is comprised of one modulation containing an a-priori known data sequence, and a second BPSK/QPSK modulation that does not contain a-priori known data. The known data is, for example, a pseudo-random periodic sequence such as the sequences used for CDMA and GNSS radio navigation modulations. The signal may further contain a frequency shift. The algorithm measures the signal’s correlation delay with respect to the a-priori known sequence and its frequency shift. The method also decodes the signal’s unknown data modulation. An example of a signal suitable for FCMH processing is the GPS signal. The GPS signal is a CDMA signal containing data bits modulation, CDMA code modulation and a frequency shift caused by the Doppler effect. Signals from other GNSS systems such as GLONASS, Galileo and Compass are also suitable for FCMH processing. The FCMH method enables detection and measurement of weak signals in challenging environments. The sensitivity achieved using FCMH better than that of non-coherent integration methods, and approaches the sensitivity of coherent integration. The advantage of FCMH over traditional coherent integration methods is that it does not require a-priori knowledge of the unknown data modulation at the receiver. FCMH uses a highly efficient computational algorithm to enable real-time processing on various platforms while using minimal resources. This article includes a theoretical derivation of the FCMH algorithm performance. It also presents experimental results with a real-life GNSS receiver that demonstrate processing gain and performance that is close to full coherent processing.
Published in:	Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011) September 20 - 23, 2011 Oregon Convention Center, Portland, Oregon Portland, OR
Pages:	2070 - 2075
Cite this article:	Shayevits, B., Tocker, M., Rosenfeld, D., "Coherent Multiple Hypotheses Detection and Measurement for Radio Navigation," Proceedings of the 24th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2011), Portland, OR, September 2011, pp. 2070-2075.
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