PPP: Solving Without a Nearby Reference at All
Every method covered so far still leans on a nearby reference of some kind, whether a physical base station or a network's modeled virtual one. Precise point positioning, PPP, gives up that reference entirely, and solves the position a genuinely different way as a result.
PPP abandons the nearby reference altogether. Instead of canceling shared atmospheric and orbital error through comparison, it models each source of error directly, using precise satellite information and sophisticated physical models, from a single receiver working entirely on its own.
A Different Philosophy, Not Just a Missing Base
RTK and PPK both rely on the same core trick: two nearby receivers experience nearly the same atmospheric and orbital error, so comparing them cancels most of it out. PPP has no second receiver to compare against, so it cannot use that trick at all. Instead, it estimates every significant error source directly: the precise satellite orbit and clock products from earlier in this companion remove most satellite-side error outright, while sophisticated models account for ionospheric and tropospheric delay, solid Earth tides, ocean loading, and antenna phase center variations, each addressed individually rather than canceled through comparison.
PPP is not RTK with the base station deleted. It replaces an entire error-cancellation strategy, comparison against a nearby reference, with a completely different one: modeling each error source directly and individually.
Why This Requires Precise Products
None of this is possible using only broadcast satellite information. PPP depends on the same precise, retrospective orbit and clock products discussed earlier in this companion, whether applied after the fact in post-processing or streamed with a modest delay for near-real-time use. Without that precise satellite information, there would be nothing accurate enough left to model the remaining error against.
PPP is not simply RTK without a base station, run with lower expectations. It is built on an entirely different foundation, precise satellite products combined with direct physical modeling, and it requires information neither RTK nor an ordinary autonomous solution ever uses.
What a Single Receiver Can Now Do Alone
Anywhere in the world, with a clear view of the sky and access to precise satellite products, a single PPP-capable receiver can compute a high-precision position with no local infrastructure of any kind, no base station to establish, no network subscription tied to a particular region, and no correction stream from a nearby source. That independence from local infrastructure is PPP's entire reason for existing.
A vessel needs a precise position far offshore, well beyond any base station or regional network's reach. Does that rule out centimeter-level positioning? Not with PPP. Since it needs no nearby reference at all, only a clear sky view and precise satellite products, location relative to any local infrastructure stops being a limiting factor.
PPP solves a position using precise satellite products and direct physical modeling of each error source, rather than canceling error through comparison against a nearby reference. It requires no local base station or network at all, working anywhere in the world under the same principle.
Working without a nearby reference comes at a real cost, and it shows up the moment a PPP receiver is turned on. The next chapter explains exactly what that cost is, and why.