An Experimental L1/L2 GNSS Receiver for High Precision Applications

In this work we present the design and implementation of a GNSS receiver that can work with the civil signals of the L1 and L2 bands of GPS and GLONASS, and the E1 Open Service signal of Galileo. The developed prototype has two RF front-ends, one for the L1 band and another for the L2 band. The signals from each band are amplified and then down-converted to an intermediate frequency. The two local oscillator tones used for the mixing, and the clock signals for the next digitalization and processing stages are generated by a frequency synthesizer board, from a common reference. The digitalization and posterior processing of the signals can be carried out using generic devices, like an acquisition board and an FPGA, according to the Software Defined Radio (SDR) concept. In this way a programmable receiver is obtained. These kinds of receivers are versatile since they can be used for testing acquisition, tracking, and navigation algorithms for research and develop purposes. Commercial receivers do not have that capability, because their digital processing stages cannot be modified by the user. Moreover, a multi-band and multi-constellation receiver allows to greatly increase the performance in relation to mass market GNSS receivers which relay on only one navigation system and one carrier frequency. Measurements realized to the implemented prototype that validate the proposed design are presented.