Development and testing of an L1 combined GPS-Galileo software receiver

The GPS L1 signal is being augmented by L1C and the European GNSS Galileo is under development. The GPS L1C and Galileo L1 signals use a common design and in particular a MBOC modulation. This dissertation investigates combined acquisition and tracking algorithms for GPS and Galileo signals in the L1 band.In term of signal acquisition, different algorithms are developed to take advantage of these new signals. Each algorithm is characterized using real data and from a statistical point of view with a focus on the false alarm and detection probabilities and the mean acquisition time. Techniques using 16 ms of incoming signal show 2--6 dB higher deflection coefficients compared to using only 8 ms of signal, but also require a higher computational load and thus the choice of the algorithm should depend on the receiver's operating conditions. An acquisition that combines the different signals (GPS L1 C/A and L1C or Galileo) is also developed and tested using the aforementioned software simulator. The combined acquisition succeeds to acquire the signal at low C/N0, whereas the acquisition using the L1C data channel only fails.For tracking, a method to combine different signals (GPS L1 C/A and L1C or Galileo) before the discriminator is developed. This method shows better performance than the traditional tracking using only one signal. Then, a method for simultaneous tracking of the GPS L1 C/A and L1C signals using a Kalman filter approach is developed and found to be preferred over traditional methods. A novel Kalman filter capable of combining and simultaneously tracking the L1 C/A and L1C signal is introduced. Testing with the software signal simulator showed that this approach improves performance of tracking in terms of accuracy and sensitivity compared to the C/A-only Kalman filter and the traditional tracking in various dynamic modes, with and without oscillator errors and at low and high signal power.Since these signals are not yet being broadcast, a software signal simulator able to simulate GPS L1 C/A, GPS L1C (pilot and data channels) and Galileo L1 (pilot and data channels) is first developed. The simulator is able to simulate white noise, different types of interference and various types of receiver oscillators. A new oscillator model was developed for the latter.