PPK: The Same Method, Delayed
Post-processed kinematic surveying, PPK, changes exactly one of RTK's two defining answers. It keeps the nearby reference. It gives up real-time delivery entirely, in exchange for something genuinely valuable in return.
PPK uses the same base-and-rover relationship as RTK, but records raw observations from both instead of differencing against a live reference stream in the field, then computes the position afterward in dedicated software. The reference is still local. Only the timing changes.
A Detail Worth Correcting Early
PPK is often described as removing the need for a base station entirely. That description is wrong, and worth correcting immediately, since it causes real confusion. PPK almost always still uses a base, whether a dedicated local base or a nearby continuously operating reference station whose data is downloaded afterward. What PPK actually removes is the live radio or internet link between that base and the rover, not the base itself.
PPK is RTK's own mathematics, applied after the fact instead of live. The base is not eliminated. The requirement for a real-time connection to it is.
How the Workflow Actually Differs
Both the base and the rover independently log raw satellite observations continuously throughout a session, each carrying its own precise internal timestamp. No correction passes between them in the field at all. Afterward, dedicated software aligns the two logged datasets by time and computes the same kind of carrier-phase solution RTK computes live, resolving integer ambiguities and canceling shared error, just hours or days later instead of in the moment.
PPK does not use a fundamentally different kind of mathematics from RTK. It uses the same differential carrier-phase approach, applied to two independently logged datasets after the fact rather than to a live, continuously streamed reference.
What Giving Up Real Time Actually Buys
Removing the live link removes an entire category of field problem: dropped radio signals, unreliable cellular coverage, and NTRIP connection failures simply stop being able to ruin a session, because nothing needs to connect in real time at all. It also opens the door to using better satellite orbit and clock information than what was available live in the field, a benefit explored fully in the next chapter.
A crew works in a canyon with no cellular signal and no radio line of sight to a base station. Does that rule out obtaining a centimeter-level solution? Not necessarily. If both the rover and a base, even one downloaded from a nearby continuous station afterward, logged raw data throughout the session, PPK can still produce the same quality of result RTK would have, computed later instead of live.
PPK keeps RTK's nearby-reference requirement but removes the live connection entirely, logging raw data from both base and rover for processing afterward. It solves the same problem RTK solves, using the same underlying mathematics, just without needing anything to stay connected in the field.
Giving up real-time delivery is not merely a workaround for bad connectivity. It also opens access to meaningfully better information than the field ever has access to live, which is worth its own careful explanation.