Tang Xiaomei

Strobe double phase estimator: a multipath mitigating technique for BOC signal in GNSS based on double phase estimator

Double phase estimator (DPE) is an unambiguous binary offset carrier (BOC) tracking algorithm for band-limited receivers in Global Navigation Satellite Systems. Based on the strobe pulse method, the DPE was modified by introducing a strobe waveform in the prompt signal correlation process of the subcarrier phase lock loop in this paper.. This strobe DPE (SDPE) employs no additional correlators. Two different reference strobe waveforms and their receiving structures are provided. The performance of the SDPE is characterized according to the subcarrier multipath error envelope (SMEE) and the tracking jitter. Simulation results show that, relative to conventional DPE, the first waveform employed in this study provides a reduction in the SMEE area of 81.1% and 75.1% for BOC(1,1) and BOC(14,2) signal, respectively. The second waveform employed in this study provides a reduction in the SMEE area of 82.5% and 76.8% for BOC(1,1) and BOC(14,2) signal, respectively. They also both outperform the double estimator about 64.4% and 53.2% for BOC(1,1) and BOC(14,2) signal in the SMEE area. However, the SDPE experiences a loss of 6 and 7:25 dB, respectively, for two reference waveforms in terms of the post-coherent signal-to-noise ratio, which impacts its tracking precision. Copyright

Direct acquisition method of long PN-code based on the GPU

In order to solve the acquisition problem of long PN-code spread spectrum signals, the partly correlation code phase-space acquisition model and implementation method of the FFT are analyzed. In order to segment data processing tasks and make full use of GPU to speed up FFT, a partly overlapped segmentation acquisition method of long PN-code is researched. Implementations of a direct global searching method and a partly overlapped segmentation searching method based on the GPU are then proposed, which parallel search for code phase using the FFT method, and accelerate FFT using the GPU. Simulation results indicate that, compared to a CPU implementation method, the search speed of the direct acquisition method of long PN-code based on the GPU is improved significantly.

OLCD: Optimal Linear Combinational Detector in GNSS Signal Acquisition

Signal acquisition is a process of two-dimensional search in time/frequency domain and signal detection in multiple search bins. The hypothesis testing of current signal acquisition algorithms are made according to correlation of a single bin; however, according to the effect of code phase and Doppler frequency error, signal presence could be detected on multiple bins. Based on the principle, the optimal linear combinational detector (OLCD) without increasing the hardware complexity is proposed. At last, simulation result with common acquisition parameters shows that the acquisition performance of OLCD is about 1 dB better than that of traditional detector.