N-Gene: A Complete Gps And Galileo Software Suite For Precise Navigation

N-Gene is a GNSS receiver developed following the software radio approach. N-Gene can be executed on a standard commercial Linux personal computer, only an external USB radio frequency front-end must be attached to the computer in order to shift the input signal to an intermediate frequency and convert it to the digital domain. Anyway, N-Gene is not simply an example of the possibility to implement a fully software real-time receiver, but it represents a sophisticated machine complete of all the functionalities available on commercial products, including demodulation of navigation message, Position Velocity Time (PVT) calculation and PVT outputs display. In order to obtain a reliable navigation, N-Gene is extremely versatile both for static and dynamic environments and its finite state machine that supports all the receiver functionalities is able to handle any kind of impairments the receiver could face during its functioning in a urban environment. Among other strategies implemented in the N-Gene receiver, a sophisticated algorithm based on the propagation of Bayes joint probability is used to continuously monitor the presence or absence of a satellite signal in order to check if the channel is temporarily in outage mode. In this way the receiver is able to use a satellite for pseudorange evaluation even if the receiver is not fed by the satellite signal due to the presence of obstacles.