A document discusses a method by which GMSK (Gaussian minimum shift keying) modulation and a pseudonoise (PN) ranging signal may be combined. By isolating the in-phase and quadrature components after carrier lock, and extracting their low-pass and band-pass filtered components, there is enough information available to both demodulate data and track the PN signal. The proposed combined GMSK communications and PN ranging is one potential approach to address emerging requirements for simultaneous high data rate communications from and tracking of vehicles in deep space or at the Moon.

GMSK and PN ranging have not been previously combined, and the corresponding receiver structure for such combined ranging has not been proposed in the past. A key advantage is that the combined signal is bandwidth-efficient and it is a constant envelope modulation, allowing high-power amplifiers to operate at saturation for highest efficiency.

This work was done by Richard Orr of SATEL LLC and Dariush Divsalar of Caltech for NASA’s Jet Propulsion Laboratory.


This Brief includes a Technical Support Package (TSP).
Combined GMSK Communications and PN Ranging

(reference NPO-45108) is currently available for download from the TSP library.

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This article first appeared in the November, 2008 issue of NASA Tech Briefs Magazine.

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