Performance Evaluation of C/N0 Estimators Using a Real Time GNSS Software Receiver

The high level of flexibility achievable with software defined radio (SDR) technology generates interest in the industry of mass market receivers, but represents also a valuable tool for research-oriented analysis. This paper exploits this last aspect and demonstrates how it is possible to assess the performance of different digital estimators of C/N0 (i.e., the carrier power to noise power spectral density ratio) using a real time SDR Global Navigation Satellite System (GNSS) receiver. In a GNSS receiver the measure of C/N0 is not only a measure of the strength of the received signal, but is also used to determine the lock condition of the carrier and tracking loops and to control the channel scheduling. This paper investigates the possibility of implementing various low complexity C/N0 estimators, properly adapted from the digital communications world. After a theoretical analysis, the performance of such estimation techniques are assessed through both simulated and real GPS signals.