Design of a Stable Discrete Time Costas Loop

Jonathan M. Hill and William R. Michalson

Abstract:	A commonly used approach to achieve carrier phase-lock in a GPS receiver is to employ a discrete-time Costas Loop. Typically the discrete time loop is derived from a continuous time model. However, continuous time models are not adequate in correctly characterizing the stability and tr ansient response of the discrete time Costas Loop. This paper provides an in-depth investigation into the stability and transient response of the discrete time Costas Loop. A simplified uniform-rate sampled model is proposed and used as a basis for stability and transient response analysis. The phase ramp response, which corresponds to a constant Doppler Shift, is simulated. Finally measured results from an actual design based on this model are presented.
Published in:	Proceedings of the 2001 National Technical Meeting of The Institute of Navigation January 22 - 24, 2001 Westin Long Beach Hotel Long Beach, CA
Pages:	228 - 234
Cite this article:	Hill, Jonathan M., Michalson, William R., "Design of a Stable Discrete Time Costas Loop," Proceedings of the 2001 National Technical Meeting of The Institute of Navigation, Long Beach, CA, January 2001, pp. 228-234.
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