RTK, network RTK, PPK and GNSS/INS

Methods

RTK resolves carrier-phase ambiguities using timely reference data. Network RTK uses a reference-station network to model spatial errors; VRS, FKP and MAC are different delivery approaches requiring compatibility checks. PPK processes recorded rover and reference data after the mission: useful for offline results, but no substitute for navigation needed in real time.

Format and transport

RTCM specifies standardised GNSS messages; NTRIP transports GNSS data over IP. Neither is itself a positioning algorithm. Mountpoint, RTCM version, message types, authentication, GGA return messages and update rates must match at both ends.

Fixed, Float and GNSS/INS

Fixed indicates an integer ambiguity solution; Float uses ambiguities not fixed to integers. Fixed is not an integrity certificate. GNSS/INS combines satellite and inertial observations. INS can propagate through a GNSS gap, but uncertainty grows; permissible duration comes from tests of the actual IMU and motion.

Relevant next steps