A joint carrier and data estimation scheme for real-time high dynamics GNSS receivers

Real-time GNSS receivers usually track the navigation satellite signals by means of code and carrier loops. In previous works we derived optimum loop filters and introduced the UFA discriminator to improve the PLL response to acceleration steps expected in launching vehicles. In this paper we present a data detection strategy based on the Per Survivor Processing (PSP) technique to use a four quadrants angle phase discriminator. The proposed scheme makes use of two parallel tracking loops and commutes between them based on the data decisions. Simulations show that 30g steps can be efficiently tracked with signal levels as low as C/N₀ = 28 dB-Hz. The performance is similar to the obtained with more complex schemes and represents a 4 dB reduction in tracking threshold with respect to the single loop estimator.