PPK (Post-Processed Kinematic): The Alternative to RTK When You Don't Have a Signal

Introduction

RTK requires a continuous data link for corrections. But what if you're flying a drone beyond radio range? Working in a valley with no cell service? Mapping a forest where signals come and go? Enter PPK.

What Is PPK?

Post-Processed Kinematic is a technique where you log raw GNSS data in the field and process it later with base station data to achieve centimeter accuracy, without needing real-time corrections.

How PPK Works

In the field

1. Set up base station (or identify nearby CORS)
2. Rover logs raw observations (carrier phase, code, time)
3. Continue logging throughout work
4. No corrections needed in real-time

In the office

1. Download rover data
2. Obtain base station data (your base or CORS)
3. Process together using PPK software
4. Apply same algorithms as RTK (but after the fact)
5. Export centimeter-accurate positions

PPK vs. RTK

PPK for Drones: The Killer App

PPK has revolutionized drone mapping. The real-time problem: drones fly beyond radio range, losing corrections and RTK fix. PPK solves this elegantly, the drone logs raw data during flight, the base station logs continuously, and you process everything after landing to get centimeter-accurate orthomosaics without ground control points.

Workflow

1. Set up base at takeoff point (or use CORS)
2. Fly mission, logging raw GNSS
3. Download drone and base data
4. Process in PPK software
5. Generate georeferenced outputs

PPK for Forest Surveys

Forests are challenging for RTK, canopy blocks signals intermittently, causing constant loss of fix. With PPK, you log continuously (the receiver tracks when possible), bridge signal gaps, and process with nearby CORS data for far better results than real-time work would achieve.

PPK Processing Steps

1. Data preparation, Convert raw data to RINEX format, verify time synchronization, check data quality
2. Base-rover synchronization, Align timelines, identify common satellites
3. Processing, Double-differencing, ambiguity resolution, quality control
4. Export, Coordinates, quality metrics, visualization

Software Options

Vital Points

• PPK achieves RTK accuracy without real-time corrections
• Perfect for drones, forests, and remote areas where data links are unreliable
• Log raw data now, process later, no data link required in the field
• Can bridge signal gaps that would break RTK
• Essential tool for challenging environments