Method and system for doppler estimation
Aspects of a method and system for Doppler estimation may include generating, in a GNSS receiver operating in a duty-cycle mode, a plurality of lag-m products that may be based on a plurality of correlation coefficients corresponding to one or more received signals, wherein the plurality of correlation coefficients may be generated during an active period of the duty-cycle mode of operation. A Doppler frequency may be estimated based on the plurality of lag-m products. The GNSS receiver may be compliant with one or more standards comprising GALILEO, GLONASS, IRNSS, and BEIDOU. The active period of the duty-cycle mode may be chosen arbitrarily from a range of 1% to 99%.
1. A method for processing satellite signals, the method comprising:
generating in a GNSS receiver operating in a duty-cycle mode, a plurality of lag-m products based on a plurality of correlation coefficients corresponding to one or more received signals, wherein said plurality of correlation coefficients are generated from blocks of data during an active period of said duty-cycle mode of operation; and
estimating a Doppler frequency iteratively based on said plurality of lag-m products.
2. The method according to claim 1 , wherein said GNSS receiver is compliant with one or more standards comprising GALILEO, GLONASS, IRNSS, and BEIDOU.
3. The method according to claim 1 , wherein said active period of said duty-cycle mode is chosen arbitrarily from a range of 1% to 99%.
4. The method according to claim 1 , comprising generating said plurality of lag-m products corresponding to said one or more received signals utilizing a relationship:
R i =C i C i−1 *,
where R i denotes a lag-1 product at a time index i, C i denotes a correlation coefficient at a time index i, and .* denotes complex conjugation.
5. The method according to claim 1 , comprising generating said plurality of correlation coefficients by correlating a sampled received baseband signal corresponding to at least one of said one or more received signals with a local copy of a coarse acquisition (CA) code.
6. The method according to claim 1 , comprising estimating said Doppler frequency by averaging said plurality of lag-m products, and taking an argument of said average.
7. The method according to claim 6 , comprising scaling said averaged plurality of lag-m products for said estimation of said Doppler frequency.
8. The method according to claim 1 , comprising iteratively estimating said Doppler frequency by frequency-compensating said plurality of correlation coefficients via a first Doppler frequency estimate before forming said plurality of lag-m products.
9. The method according to claim 1 , comprising taking an argument of a complex quantity for said estimating of said Doppler frequency.
10. The method according to claim 9 , comprising approximating said argument of said complex quantity by an imaginary signal component of said complex quantity.
11. The method according to claim 9 , comprising approximating said argument of said complex quantity by an arbitrary numerical method.
12. A system for processing satellite signals, the system comprising:
one or more circuits in a GNSS receiver that operates in a duty-cycle mode, wherein said one or more circuits are operable to:
generate a plurality of lag-m products based on a plurality of correlation coefficients corresponding to one or more received signal, wherein said plurality of correlation coefficients are generated from blocks of data during an active period of said duty-cycle mode of operation; and
estimate a Doppler frequency iteratively based on said plurality of lag-m products.
13. The system according to claim 12 , wherein said GNSS receiver is compliant with one or more standards comprising GALILEO, GLONASS, IRNSS, and BEIDOU.
14. The system according to claim 12 , wherein said active period of said duty-cycle mode is chosen arbitrarily from a range of 1% to 99%.
15. The system according to claim 12 , wherein said one or more circuits generate said plurality of lag-m products corresponding to said one or more received signals utilizing a relationship:
R i =C i C i−1 *,
where R i denotes a lag-1 product at a time index i , C i denotes a correlation coefficient at a time index i, and .* denotes complex conjugation.
16. The system according to claim 12 , wherein said one or more circuits generate said plurality of correlation coefficients by correlating a sampled received baseband signal corresponding to at least one of said one or more received signals with a local copy of a coarse acquisition (CA) code.
17. The system according to claim 12 , wherein said one or more circuits estimate said Doppler frequency by averaging said plurality of lag-m products, and taking an argument of said average.
18. The system according to claim 17 , wherein said one or more circuits scale said averaged plurality of lag-m products for said estimation of said Doppler frequency.
19. The system according to claim 12 , wherein said one or more circuits iteratively estimate said Doppler frequency by frequency-compensating said plurality of correlation coefficients via a first Doppler frequency estimate before forming said plurality of lag-m products.
20. The system according to claim 12 , wherein said one or more circuits take an argument of a complex quantity for said estimating of said Doppler frequency.
21. The system according to claim 20 , wherein said one or more circuits approximate said argument of said complex quantity by an imaginary signal component of said complex quantity.
22. The system according to claim 20 , wherein said one or more circuits approximate said argument of said complex quantity by an arbitrary numerical method.