DJI M300 RTK

For full specifications see the DJI website: MATRICE 300 RTK - Specifications - DJI

The M300 RTK supports a range of sensors from the DJI - Zenmuse stable with highly sophisticated, out-of-the-box integration and operational tools. It can also operate third party sensors either as standalone sensors operating independently of the aircraft system (apart from power, which can be provided), or with more complex support through the available SDK. Currently available sensors are listed below, but please contact us if you would like to discuss integrating any additional systems.

The M300 RTK is able to provide positional data with centimetre-level accuracy to fully supported sensors such as the L1 LiDAR, the P1 photogrammetry sensor and the XT2 thermal camera. There are various options for providing the real-time RTK GNSS corrections and translating high relative positioning accuracy to high absolute accuracy.

Using the D-RTK-2 Mobile Station

Our D-RTK-2 mobile station is specifically designed to support DJI's RTK-equipped aircraft such as the M300 RTK and Phantom 4 RTK by providing real-time corrections to the aircraft which yield cm-level relative positioning accuracy between the mobile station and the aircraft. This system is entirely stand-alone and does not require any external network or mobile connectivity, so it is suitable for use in all environments, even where strong stable 4G mobile connectivity cannot be assured.

While this relative positioning accuracy will be enough for many applications, it is important to note that the mobile station does not, by default, know it's own position in absolute terms to the same level of accuracy. To achieve cm-level absolute positioning accuracy additional steps are therefore required. There are various options as outlined below:

1. If the absolute position of the D-RTK-2 mobile station is already known to cm-level accuracy by pre-survey, this data can be input directly into the D-RTK-2 during set-up in the field. The corrections are then incorporated in the real-time data transmitted to the aircraft and logged in the acquired data.
2. If the absolute position of the D-RTK-2 mobile station is not known in advance, but surveyed on the same day as the flight acquisition, the accurate position of the station can be entered into the DJI Terra software during initial post-processing of the acquired data, which will then update the positional information throughout the dataset.
3. We are looking into workflows to process the recorded D-RTK-2 data against external base station networks (e.g. Ordnance Survey) in post-processing, to produce an accurate reference against which to correct the acquired flight data. This would remove the need to independently survey the  D-RTK-2 location. Note that this is a work in progress and not yet in place.

Using Network RTK

If a stable 4G mobile connection can be assured, it is possible for the M300 RTK to use a mobile connection to receive real-time corrections from commercial networks of RTK base stations, which negates the need for the D-RTK-2 mobile station and reduces the amount of field equipment required.

This workflow requires both a strong and stable 4G mobile network connection at the operating site and also access to a commercial RTK network with nearby base stations, which may not be available in some parts of the world. Access to such networks incurs cost, typically of around £25 / day for access to the RTK base station network, and of course any charges for mobile network access (e.g. via hotspot or dongle).

Note that while such base stations should know their own positions to high accuracy, we believe that there will be a dilution of positional accuracy with increasing distance between the selected network base station and the aircraft of around 1ppm. At time of writing we are yet to test and evaluate this workflow; due to the remote nature of the majority of our work, 4G connections cannot usually be assured and the D-RTK-2 workflow above is our default mode of operation.

Use of Ground Control and Check Points

The M300's RTK positioning system provides very accurate data tagging as outlined above. In many cases this may be considered to negate the need for any ground control points. However, for those applications where absolute positioning and / or scale accuracy are critical, it remains good practice to also incorporate independently surveyed ground control points (to further constrain the generated models) and / or check points (to provide an accuracy assessment of the final product). Typically 8-10 ground control points and 4-6 check points should be distributed around the survey area. If it is not possible to access the survey area for ground control point distribution and survey, then check points around the take-off and landing site may still provide a useful degree of accuracy assessment. 

We operate a Leica GPS 500 survey system for the survey of ground control points, check points and the location of the D-RTK-2 mobile station. This is included as an optional add-on to the M300 RTK carrying system as outlined below. For eligible projects more modern and compact survey systems are also available through the NERC Geophysical Equipment Facility (GEF).

The complete M300 system is back-pack portable, typically requiring 3 loads, and an additional 1-2 loads if an independent GNSS ground survey is required.

We have developed a carrying system suitable for most deployments as outlined below. Each pack retains around 20-30 litres of free space for personal equipment.

The M300 RTK with L1 LiDAR / Photogrammetry and P1 photogrammetry sensors is fully operational and ready for immediate deployment. Please see the 'Working With Us' section of this website for more information, and contact us to discuss your requirements.

We currently have 4 battery sets for the M300, each providing around 25 minutes of useful flight time. However we can support in-field recharging using our portable generator, so can essentially keep the aircraft operating all day long when we have 4x4 access.

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