GNSS Software Receiver Signal Simulation And Captured

In the development of modern GNSS receiver, application software-defined radio technology represents a stage in the evolution of the procedure. In contrast to the conventional receiver with a dedicated integrated circuit, software radio through a programmable microprocessor or digital signal processor to implement all of the digital signal processing.It separate the hardware analog signals environmental conditions from the digital signal processing in the software, this led to the obvious advantages, such as Multi-modeling, multi-system, multi-sensor, testing, quality control and software development ongoing. In the GNSS case, this signal processing method is particularly important. Software receiver is becoming an increasingly important design concepts. The actual software receiver, deal with the limited bandwidth of the signal, select the sub-band of the continuous band, software receiver achieved using existing technologies.The key technologies of GNSS software receiver included satellite signal acquisition and tracking technology. In order to track the satellite signal and decode the information, it should firstly capture program so that it can monitor the presence of a signal. Once detecting the signal, it must sent the necessary parameters to the tracking process. Then, it will get useful information such as navigation message by tracking program. Thus it can be seen that the signal capture is essential in the process of researching GNSS software receiver.This paper firstly introduces the profile and main characteristics of the three commonly satellite navigation system. Furthermore, it focus on the signal structure and modulation of each satellite navigation system. Start from the basic binary random sequence, the paper presents the generation mechanism of M codes and the GOLD code and leads to the GPS satellite C/A code allocation provisions. After the completion of this work, it describes the modulation principle of satellite signal ranging from simple BPSK to BOC. It introduced their own characteristics and applied range starting from the principle, even simulation was be done in Simulink environment.Secondly, on the basis of the signal processing, the main methods to satellite high-frequency signal is described, including sampling and quantization. Finally, based on the above-mentioned signal processing completed, this article begins to discuss three common capture method of the satellite navigation software receiver:serial capture, parallel frequency domain to capture and parallel code phase acquisition. This article has achieved the above-mentioned three methods by M language. Moreover, as the example of actual GPS if signal acquisition, it has verified optimal parallel code phase.