The stage is implemented by the NMEA 0183 parser, which
analyzes data from the GPS receiver (NMEA sentences GPGGA,
GPGSA, GPGSV and GPRMC) and extracts the necessary for the
proposed algorithm GPS data: number of visible satellites; satellite position – azimuth and elevation; SNR for each satellite;
Horizontal Delution of Precision (HDOP) – estimation of horizontal accuracy of GPS receiver; WSG 84 user position (longitude and
latitude) and velocity.