The main objective of the SoftGNSS project is the development of a software defined Global Positioning System (GPS) receiver whose performance is enhanced by a dual-frequency approach. The combined processing of the L1 and L2c GPS frequency allows for mitigating measurement errors, as for example errors caused by distortions introduced in the Ionosphere. An improved receiver accuracy makes the application of GPS beneficial for an even wider range of applications as compared with todays performance obtained through a single frequency approach. The software defined nature of the system facilitates the adaptation of the receiver to prospective GPS specifications and future Global Navigation Satellite Systems (GNSS), i.e. Galileo, altogether.
The receiver comprises a RF front end, a digital signal processing unit and a position, velocity and time (PVT) module. The RF front end receives the GPS satellite signals, modulates the received signal to an intermediate frequency and digitizes it. The digital signal processing unit screens the signal for visible satellites, compensates each satellite signal for delay and frequency shifts and extracts the raw data. In the next stage, the PVT module computes the satellite and receiver position from the raw data while utilizing different error correction algorithms.