Dynamic Carrier Tap Selection (DyCaTS): A Novel Approach for GPS M-code Pull-in

Ryan S. Cassel, Lawrence Elentukh, Shawn D. Miller

Peer Reviewed

Abstract:	For binary offset carrier (BOC) signals whose auto-correlation functions have multiple peaks, unambiguous code discriminators using extra taps can remove the effects of the correlation ambiguity and provide unambiguous code tracking. However, during code pull-in, the prompt tap, which is typically used for carrier tracking, traverses the peaks and nulls of the correlation function. When it lands in a null, carrier tracking accuracy can suffer and pull-in can fail, diminishing the benefits of the unambiguous code discriminator. In response, we describe a novel approach for GPS M-code pull-in that overcomes this issue and increases the code pull-in range, called dynamic carrier tap selection (DyCaTS). Its operating principle is to dynamically select the tap with the highest correlation output power and use it for carrier frequency tracking, thereby overcoming the loss of correlation power at the prompt tap as it traverses the nulls of the correlation function. We show through Monte Carlo simulation that DyCaTS, when paired with an unambiguous eight-gate M-code discriminator, can significantly increase the code pull-in range for full-band M-code tracking at low carrier-to-noise. The intuition behind DyCaTS, as well as its flexibility and low implementation cost, suggest that it can also be applied to other GNSS signals with other code discriminators.
Published in:	Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023) September 11 - 15, 2023 Hyatt Regency Denver Denver, Colorado
Pages:	3513 - 3526
Cite this article:	Cassel, Ryan S., Elentukh, Lawrence, Miller, Shawn D., "Dynamic Carrier Tap Selection (DyCaTS): A Novel Approach for GPS M-code Pull-in," Proceedings of the 36th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2023), Denver, Colorado, September 2023, pp. 3513-3526. https://doi.org/10.33012/2023.19263
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In