Introduction
RTK gives fast convergence and centimeter accuracy but requires nearby base stations. PPP works globally but takes 30 minutes to converge. What if you could have both? Enter PPP-RTK.
The Problem It Solves
Standard RTK
- Fast (seconds to fix)
- Centimeter accuracy
- Limited range (10–30 km)
- Needs base station
Standard PPP
- Global coverage
- No base needed
- Slow convergence (30+ minutes)
- Lower accuracy (5–20 cm)
PPP-RTK
- Fast convergence (seconds to minutes)
- Wide area coverage (hundreds of km)
- Centimeter accuracy
- No local base needed
How PPP-RTK Works
- Regional network of reference stations (like CORS)
- Central processor computes precise orbits, clocks, atmospheric corrections, and biases for ambiguity resolution
- Corrections broadcast via satellite or internet
- Rover applies corrections, resolves ambiguities quickly
- Centimeter accuracy achieved in seconds
Method Comparison
| Method | Accuracy | Convergence | Coverage | Infrastructure |
|---|
| RTK | 1–3 cm | 30–60 sec | Local (10 km) | Single base |
| Network RTK | 2–4 cm | 30–60 sec | Regional | CORS network |
| PPP | 5–20 cm | 20–40 min | Global | Global network |
| PPP-RTK | 2–5 cm | 1–5 min | Regional | CORS network |
Available PPP-RTK Services
| Service | Region | Accuracy | Delivery |
|---|
| Trimble RTX Fast | Global (with regional) | 2–4 cm | Satellite/internet |
| Galileo HAS | Europe expanding | 10–20 cm (target) | Satellite |
| QZSS CLAS | Japan | 3–5 cm | Satellite (L6) |
Real-World Applications
- Autonomous vehicles: Need fast convergence and reliability in urban areas
- Precision agriculture: Wide-area coverage without setting up bases
- Construction: Regional projects can use single subscription
- Drones: Beyond visual line of sight operations
Vital Points
- PPP-RTK combines fast convergence with wide-area coverage
- Uses regional networks to model all error sources
- Centimeter accuracy in minutes over hundreds of km
- Better than RTK for wide-area operations
- Better than PPP for time-critical applications
- The future of high-precision GNSS