Glossary
RTK vs PPK (GNSS correction methods)
Two ways to get centimetre-grade GNSS positioning on a drone: RTK corrects the position live during the flight over a radio or cell link, while PPK logs raw satellite data and corrects it afterward in software.
Definition
Both RTK (Real-Time Kinematic) and PPK (Post-Processed Kinematic) sharpen a drone's raw GNSS fix from metres to centimetres by comparing it against a fixed reference — a local base station or a network correction service. The difference is when the maths happens. RTK streams the correction to the aircraft in real time, so the drone knows its centimetre position while it is flying; if the link drops, the correction pauses until it reconnects. PPK records the raw satellite observations on the aircraft and the base throughout the flight, then aligns the two datasets on a computer afterward, so a momentary radio or cell dropout does not cost you accuracy — it is reconstructed in processing.
In an Alberta Context
Alberta fields are large and often out of reach of reliable cell coverage, and a radio link to a base station can be interrupted by terrain, shelterbelts, or distance. That makes the choice practical rather than academic. Choose RTK when the drone needs its centimetre position live — following planned spread lines, holding a tight track, and logging an as-applied record during a spreading pass — and a correction is reliably available, either over cell (an NTRIP network correction) or a local radio link to a nearby base. Choose PPK when the priority is a clean, gap-free survey and you would rather guarantee accuracy in processing than depend on an unbroken live link over a far quarter — typical of mapping and elevation work. Many operators run their own base station on a known point so they are not reliant on a distant network correction, and both methods can be paired with a few ground control points on a known coordinate as an accuracy check.
Why It Matters
Centimetre positioning is what makes the rest of the work trustworthy. A prescription map, an as-applied record, a drainage elevation model, and even a tidy spread pattern all rest on the drone knowing precisely where it is. Choosing RTK vs PPK is really about how you want to protect that accuracy — live over a link, or rebuilt afterward from logged data — given how far from cell coverage the field sits and whether the job needs the position in real time. A caveat worth setting: neither method is magic. Poor satellite geometry, a heavy canopy, or bad antenna placement can degrade either one, a brief RTK dropout falls back to a coarser fix until the link returns, and PPK only reconstructs accuracy if the raw logs were actually recorded on both the drone and the base.
Frequently Asked Questions
+What is the difference between RTK and PPK?
Both deliver centimetre-grade positioning by comparing the drone's GNSS against a fixed reference. RTK applies the correction in real time during the flight over a live link, so the drone knows its precise position as it flies. PPK logs the raw satellite data on the aircraft and the base and aligns them in software after the flight, so a dropped link does not cost accuracy because it is reconstructed in processing.
+Which is better for drone mapping, RTK or PPK?
PPK is often preferred for mapping because it does not depend on an unbroken live link across a large field — accuracy is guaranteed in post-processing. RTK is the better fit when the drone needs its centimetre position live, such as holding planned lines during a spreading pass. Neither is universally better; it depends on the job and the coverage.
+Do I need cell service for RTK?
You need a live correction source, which is either a network correction over cell or internet, or a radio link to a local base station. On Alberta fields out of reliable cell range, operators commonly run their own base station rather than depend on network coverage. PPK avoids the live-link requirement entirely by correcting after the flight.
+Does RTK or PPK affect prescription and as-applied accuracy?
Yes — both are the foundation under it. Centimetre positioning is what lets a drone follow a prescription map by management zone and log a trustworthy as-applied record of where product actually landed. Without RTK or PPK correction, a raw GNSS fix is only accurate to a few metres, which is too coarse for zone-level work.
+Is RTK or PPK more accurate?
For accuracy alone they are effectively a tie — both resolve position to a few centimetres when the GNSS data are good, and the difference is reliability under real conditions rather than a headline number. RTK gives you that position live but pauses when the link drops; PPK guarantees it in processing as long as the raw logs were recorded. The better choice is the one that protects accuracy for how and where you are flying, not the one with a bigger spec.
+Do I still need ground control points with RTK or PPK?
Often not for the positioning itself, since the base correction already ties the survey to a known coordinate. Many operators still lay a few ground control points on a known point as an independent accuracy check, especially on elevation and drainage work where a vertical error would carry into the design. It is a verification step, not a substitute for RTK or PPK.