Oscillator phase noise has a negative effect on the tracking performance of Global Navigation Satellite System (GNSS) receivers. To provide GNSS software receivers with real test environments, this paper proposes a method to simulate the GNSS Intermediate Frequency (IF) signal, taking the oscillator phase noise effect into consideration. The oscillator parameters are first measured via a pseudolite transmitter and receiver system. According to the measured oscillator parameters, an oscillator-induced frequency fluctuation is then generated, and added to the digital IF signal. Further simulation experiments are conducted that attempt to measure the oscillator phase noise effect on a second-order Phase Lock Loop (PLL) performance. Results indicate that the IF signal simulator considering the oscillator phase noise is able to provide software receivers with real signal dynamics, helping to evaluate the performance of signal processing algorithms on a software platform.

The acquisition of signals is a precondition for tracking and solution calculation in software-based Global Navigation Satellite System (GNSS) receivers. The Parallel Code phase Acquisition (PCA) algorithm can simultaneously obtain the correlation results at every sampling point. However, if the number of sampling points that needs processing is large, this method will lead to a heavy computational load. Thus, we improve the process of the PCA algorithm and propose a novel algorithm that divides the signals into K (K is a constant) parts to achieve correlation and obtains the correlation results with a fusion algorithm. This algorithm can simultaneously obtain the correlation results for sampling points at an interval of K points. If the K value is selected appropriately, the computational load can be decreased by about 50%. Also, the Receiver Operating Characteristic (ROC) curves show that under a certain probability of false alarm, the detection probability of the proposed algorithms is 5% lower than that of the PCA algorithm. Therefore, the proposed algorithm can speed up the acquisition process with a slight decrease in detection probability.

Binary Offset Carrier (BOC) modulation signals have been applied in Global Navigation Satellite Systems (GNSS) because they offer a higher positioning accuracy and higher multipath rejection. However, there is a drawback in that the autocorrelation functions have multiple side peaks, meaning that this technique also leads to the large main peak estimation error problem and a low correlation decision efficiency problem. In this paper, we propose a new Main Peak Extraction (MPE) method for high-order BOC signals to solve these problems. In the new method, the synthesis cross-correlation function is established, and the geometry graph is formatted to calculate the estimation main peak. We eliminate all side peaks and improve the main peak phase estimation precision under the condition that the sub-carrier phase is offset. The results of the simulation demonstrate that the new method can achieve better main peak decision efficiency, side peak cancellation ability and phase estimation performance than traditional methods.

Beidou is the Global Navigation Satellite System (GNSS) being developed in China, with the aim to provide a global navigation service that is similar to the Global Positioning System (GPS) and Galileo navigation systems. In this paper, it is demonstrated that through the flexibility and re-configurability of a PC-based software receiver in which the baseband operations are realized in terms of software, it is possible to acquire, track, and demodulate Beidou satellite signals even when only a limited amount of information is known. Further, with the Beidou interface control document now available, the proposed PC-based software receiver can be easily adapted to perform navigation functions. This research lays the foundation for the further development of navigation receivers and exploration of multi-GNSS applications.

These days, Global Navigation Satellite System (GNSS) technology plays a critical role in positioning and navigation applications. Use of GNSS is becoming more of a need to the public. Therefore, much effort is needed to make the civilian part of the system more accurate, reliable and available, especially for the safety-of-life purposes. With the recent revitalization of Russian Global Navigation Satellite System (GLONASS), with a constellation of 20 satellites in August 2009 and the promise of 24 satellites by 2010, it is worthwhile concentrating on the GLONASS system as a method of GPS augmentation to achieve more reliable and accurate navigation solutions.