Introduction
Do you need answers now, or can you wait? This fundamental question determines whether you need real-time positioning or if post-processing will work. Each approach has its place.
Real-Time Positioning
What it is: Position calculated immediately, displayed to user.
Technologies: Standard GNSS (meters), DGNSS (decimeters), RTK (centimeters), PPP (decimeters after convergence)
Advantages
- Immediate results
- Navigation possible
- Can guide actions (auto-steer)
- Quality control in field
Disadvantages
- Requires data link for corrections
- More equipment in field
- Higher power consumption
- Less processing time for quality
Post-Processing
What it is: Raw data logged, processed later in office.
Technologies: PPK, static processing, post-processed PPP
Advantages
- No data link needed
- Can use best possible corrections
- More processing time = better quality
- Can re-process with improved products
- Lighter field equipment
Disadvantages
- No results in field
- Can't verify coverage until later
- Risk of missing data
- Need to return if problems found
When to Choose Real-Time
| Scenario | Why Real-Time |
|---|---|
| Auto-steer tractor | Need immediate guidance |
| Construction staking | Need to mark now |
| Navigation | Need to know where you are |
| Drone mapping | Need to ensure coverage |
| Dangerous areas | Need to stay safe |
When to Choose Post-Processing
| Scenario | Why Post-Processing |
|---|---|
| Remote areas | No data link available |
| Forest mapping | Signals poor, need extra processing |
| Highest accuracy | Can use best orbits/clocks |
| Scientific research | Need maximum quality |
| Budget projects | Cheaper equipment |
PPK: The Best of Both?
Post-Processed Kinematic combines elements of both:
- Log raw GNSS data in field (like RTK rover)
- No corrections needed in real-time
- Process later with base station data
- Achieves RTK-like accuracy
Perfect for: Drone mapping, forest surveys, urban areas with intermittent signal.
Quality Comparison
| Method | Typical Accuracy | When Known |
|---|---|---|
| Real-time RTK | 2–5 cm | Immediately |
| Post-processed RTK | 1–3 cm | After processing |
| Real-time PPP | 10–20 cm | After convergence |
| Post-processed PPP | 2–5 cm | Next day (with final orbits) |
| Static (hours) | <1 cm | After processing |
Vital Points
- Real-time for immediate results, post-processing for maximum quality
- PPK bridges the gap, logs now, processes later
- No data link = post-processing required
- Highest accuracy comes from post-processing with final orbits
- Choose based on: Do you need answers now? Do you have a data link? What accuracy do you need?