IF GPS signal simulator development and verification
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AbstractA software-based intermediate frequency (IF) GPS signal simulator for the L I C/A code signal is developed and verified in this thesis. The signal simulator is implemented in MATLAB with some key functions coded in C to accelerate speed of operation. A mathematical signal model is developed that expresses the digitized IF GPS signal as a function of various errors during propagation, such as satellite clock error, ionosphere error, and troposphere error; and user defined parameters, such as date and GPS time, user trajectory, expected C/No, noise density, intermediate frequency, sampling rate, front-end bandwidth, and quantization bit. The simulator is verified by comparing the simulated signal with the hardware-collected IF GPS signal in the time, frequency, correlation and position domains. Partially for the simulator verification purpose, a software GPS receiver was developed and verified, which was used to process the simulated signal to get the pseudorange and carrier phase measurements. The signal acquisition and tracking techniques originally studied and verified in this thesis were used for the first generation software receiver developed by the PLAN group of the Department of Geomatics Engineering. The receiver consists of the following modules: signal acquisition, signal tracking, bit synchronization, sub-frame synchronization and the navigation solution. It is verified by using a set of real GPS signal measurements collected by a commercial hardware frontend and comparing the tracking results and navigation solution with the corresponding results of a hardware GPS receiver.
Bibliography: p. 155-161