|Abstract:||The next-generation Global Navigation Satellite Systems (GNSS) are planning to transmit new signals for better and diversified services. Still, the legacy signals will be reserved for backward compatibility. If coexisting on the same band, new signals and the reserved legacy ones may be multiplexed into a constant-envelop composite signal before transmission. Split-spectrum modulation are widely used in new signals for frequency compatibility, and it also improves signal performance in aspects of tracking accuracy and multipath interference. However, split-spectrum modulation introduces side-peaks into the correlation function. As a result, the signal tracking process gets ambiguous and instable. Meanwhile, the coexisting legacy signals, if non-split-spectrum modulated, won’t suffer such tracking ambiguity, but their tracking accuracy is limited. Traditional receiving algorithms processes signal components separately in the composite signal. Separately processing the non-split-spectrum component can hardly obtain desirable accuracy, while separately processing the split-spectrum component asks for extra design such as Bump-Jump to deal with the tracking ambiguity. To obtain unambiguous tracking, as well as desirable accuracy, we proposed a quasi-coherent receiving algorithm for next-generation GNSS signals. Because they’re multiplexed into one composite signal and go through identical channels from transmitter to receiver, there are strong coherence between the split-spectrum and non-split-spectrum components. The proposed algorithm takes advantage of the coherence and makes a quasicoherent combination of their correlation outputs. In this way, a synthesis correlation function without side-peaks is constructed and the composite signal power is fully used. So there will no longer exist tracking ambiguity and good accuracy performance can be achieved. A series of tests were carried out to validate and evaluate the quasi-coherent receiving algorithm, including a satellite-to-receiver test and a simulator-to-receiver test. The proposed algorithm, along with traditional separately processing algorithms are implemented to process the real QZS-1 L1 signal and simulated GPS-III L1 signal. Test results showed that quasi-coherent receiving algorithm not only eliminates the tracking ambiguity but also outperforms traditional algorithms in aspects of tracking accuracy, multipath interference and tracking stability.|
Proceedings of the 2016 International Technical Meeting of The Institute of Navigation
January 25 - 28, 2016
Hyatt Regency Monterey
|Pages:||591 - 599|
|Cite this article:||
Zhou, Hengwei, Yao, Zheng, Lu, Mingquan, "A Quasi-Coherent Receiving Algorithm and its Performance Verification for Composite Signals of Next Generation GNSS," Proceedings of the 2016 International Technical Meeting of The Institute of Navigation, Monterey, California, January 2016, pp. 591-599.
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