Signal Simulation Technology Of Pseudolite Transmitter

Pseudolites studied in the paper work at the virtual satellite pattern. Their main function is to simulate the satellite signal from the really satellite on the satellite orbit through changing code phase, Doppler shift, carrier and signal-to-noise ratio. The navigation data launched by the pseudolite contains genuine satellite orbit parameters. Based on the GPS signal, the paper emphasizes on researching the digital production technology of the satellite signal and simulation technology on it. The major contents of work are submitted as follows:1. Based on the particular characteristics of the pseudolite, the pseudolite's structure and contents of navigation data are analyzed and designed in detail.2. Combined with the research of the structure of GP2021 and the way used for computing accurate travel time of the satellite signal in the receiver, a method that estimates the C/A code status parameters is given.3. The procedure frame of producing the navigation data is studied and designed, and then some key programs are achieved. The storage mode in the microprocessor of the data which needs to preserve in advance, such as initial ephemeris etc, is also studied.4. The realization process of producing signal in numeric mode is studied, and one simulation model is designed by using the tool of MATLAB/Simulink. Afterwards, based on the simulation model, the structure of C simulation program is designed, and the signal generator is realized. Thereinto, using DDS technology realizes digital sampling.5. The realization method of software correlator is studied by analyzing the structure and work principle of the GP2021, and simulation steps of software correlator are presented. At last, the C program of software correlator is finished.6. Based on the signal-processing flow of the receiver and combined with the mature arithmetic of acquisition and tracking, the processing flow of acquisition and tracking to digital intermediate frequency signal is designed and realized. The concrete realization method of the synchronous code search algorithm is studied.A main contribution in the paper is that a quite complete study platform of signal simulation system is established with C. The further research and development work can be done in the study platform.