A non-coherent architecture for GNSS digital tracking loops

In this paper, a new, noncoherent architecture for global navigation satellite system tracking loops is proposed and analyzed. A noncoherent phase discriminator, able to extend the integration time beyond the bit duration, is derived from the maximum likelihood principle and integrated into a Costas loop. The discriminator is noncoherent in the sense that the bit information is removed by using a nonlinear operation. By jointly using such a discriminator and noncoherent integrations at the delay lock loop level, a fully noncoherent architecture, able to operate at low carrier-power-to-noise density ratio (C/N-0), is obtained. The algorithms proposed have been tested by means of live GPS data and compared with existing methodologies, resulting in an effective solution for extending the total integration time.