The safest way to obtain the JNAV GPS Analyzer is through the JRC (Japan Radio Co.) Support Site . They provide the latest firmware, drivers, and utility software for the J-NAV 500 and JLR series.
Marine systems output continuous NMEA 0183 or NMEA 2000 data streams. The analyzer parses complex strings like $GPGGA (fix data) and $GPGSV (satellites in view), breaking them down into visible metrics like speed, course over ground, and altitude. Multipath and Error Correction jnav gps analyzer download link