PPK (Post-Processing Kinematic) provides much higher accuracy in GPS location when stored against images taken in a UAV. Standard GPS signals are accurate to 10’s of metres – PPK increases that accuracy to cm-levels. On board the Q-200 UAV, PPK eliminates the need for physical Ground Control Points (GCP) that are often used to gain high accuracy in surveys. This saves hours of mission planning and setup time, physically measuring location points and walking the survey site for placement.
GCPs – The underestimated part of a UAV survey
Surveys involving GCP generally run like this:
Initial site is viewed to establish useful locations for Ground Control targets.
Each location is visited with a GCP and a Differential GPS receiver to accurately place the target.
Targets may need revisiting before survey takes place.
Locations are stored for post processing reference.
In most cases – up to half of the mission time is taken up with GCP placement. GCP targets may shift or collapse with changing weather conditions – requiring the original placement to be repeated (often wasting up to an hour of survey setup time); coastal surveys can suffer from tidal changes and cliffs make it difficult to place GCPs across the survey area; general survey ground conditions can make it difficult to secure GCPs – quarries are a good example of difficult, variable ground surfaces.
The advantage of PPK – Overcoming GCPs
The PPK solution offered by QuestUAV uses a higher performance, highly-accurate receiver placed within the aircraft – following more than 10 GPS satellites at any given time and storing location information against the triggered images taken. Combined with differential signal information collected by the fixed position Ground Station (which stores signal drift and signal error values), the image locations are recalculated to a much higher accuracy – down to centimetre level in x, y and z direction.
Compared to RTK (Real Time Kinematic), PPK also eliminates the need for a real-time data link with a fixed reference station during the flight, whilst guaranteeing RTK cm-level position accuracy of the images once post-processing has taken place, after the UAV lands. This simplifies the UAV set-up, reduces the requirements and power drain on-board and eliminates any loss of accuracy in data due to potentially unreliable radio links – which often plague RTK UAV operations.
The Q-200 Surveyor Pro is available with PPK at purchase or as an upgrade to an existing aircraft with the provision of just the PPK QPod.
QuestUAV Q-200 Surveyor Pro
The Q-200 Surveyor Pro has been designed to allow you to capture, process and analyse your high quality mission data in the quickest way possible, drastically saving you time and money. This professional, high resolution fixed-wing UAV enables a wide range of applications across many industries – including mining, construction, engineering and land management.
QuestUAV is a UK designer and manufacturer of professional sub-7Kg and sub-2Kg, fixed-wing Unmanned Aircraft, that are designed to carry multi-sensor payloads. QuestUAV Ltd is a leader in mission workflows, GIS services and provides 360 support for all products and services. The 360-degree approach defines a complete service, designed to work together with users from the first day to ongoing operations management. This approach provides the only comprehensive, integrated service, enabling seamless customer experience in a high-risk results driven environment.