Simulation of Satellite Navigation Signals and Channels

Simulation of Global Navigation Satellite (GNSS) signals in time-domain is a computationally very demanding task. High simulation sampling frequencies are needed to represent the signals' bandwidths.

Modern multi-core computers make it possible to perform such simulations in reasonable time. We developed a software simulator for the whole GNSS signal chain: GNSS signal generation - application of a channel model - software receiver.

The software is written in C++ and uses a multi-threaded approach.

SNACS was released under an open-source license.

Please visit http://snacs.sourceforge.net

This is a video where you can see SNACS running on Windows. The effects of a ride through a city on the GPS signal is simulated:

The software's structure is shown in Fig. 1

Figure 1: Structure of the GNSS software simulator.

The software is organized in independent blocks for

GNSS signal generation
filtering
application of GNSS channel models
noise generation
up-mixing to an intermediate frequency
analog-to-digital conversion
software receiver

acquisition module
PLL and DLL tracking loops

Every block works in an own thread. Time-consuming operations such as filtering and convolution additionally expand to multiple sub-threads.