• In-depth guide to help you solve custom network RTK issues;

• How to fix problems with a dongle or WiFi hotspot; 

• Ensure you have selected a reliable and respectable RTK provider, such as Premium Positioning;

• Find out how you can obtain a trial RTK licence from heliguy™, which can be used as a short-term resolution; 

• How to fly using a PPK workflow, if you can't utilise RTK.  

Welcome to our guide on troubleshooting custom network RTK (NTRIP) issues on your DJI surveying drone, such as connectivity or accuracy problems.

This blog will detail the steps you can take to try to resolve any issues that arise and ensure you can maximise the use of custom network RTK for your surveying operations.  

The guide will cover topics such as internet connectivity, RTK (real-time kinematic) providers, and how to utilise a PPK (post processed kinematic) workflow. You can find out more about the differences between RTK and PPK here.

Connecting To The Internet

To kick things off, make sure you have a strong phone signal and are connected to the internet.

If you are in an area with weak or no cellular coverage, NTRIP will not work on your drone. NTRIP is the standard protocol for streaming Global Navigation Satellite System (GNSS) correction data over the internet.

How Do I Connect To The Internet?

If you are using the DJI Mavic 3 Enterprise Series, M30 Series, or M300 RTK, you can connect to the internet by using either a hotspot or a LTE 4G dongle.

The DJI Phantom 4 RTK only allows connection via hotspot.

What If The LTE 4G Dongle Or Hotspot Do Not Work?

If you are using the dongle, make sure you have sufficient data on the SIM card inserted into the device.

If the dongle is not working, or you would rather use a hotspot, try connecting to a hotspot through your phone.

To do this, go into the WiFi settings on the drone's controller and connect to the hotspot from your phone. If the hotspot password is not available on the RC, refresh it on your phone.

If the hotspot is not working, try removing the SIM from your phone and place it into the dongle instead. The dongle can then be placed in the underside of the smart controller. For more information on how to do this, you can check out the Zenmuse L1 Free online course, developed and delivered by heliguy™.

Alternatively, if you have a D-RTK 2 Mobile Station, you can use this instead, as it communicates to the drone via a radio link.

If you have successfully connected to RTK, the RC screen should look like this and display a fixed RTK connection.

Still No Success? Determine Your RTK Provider

If you have tried these steps and are still experiencing issues, determine what provider you are with for your NTRIP account.

If you are with a provider such as Premium Positioning, Trimble VRS, Leica SmartNet or TopNet, your NTRIP account is most likely secure and you should be receiving an accurate RTK signal.

Certain RTK networks can cause issues when used with the device, especially if they are purchased at a significantly cheaper cost. Therefore, ensure you have access to a robust and recognised RTK correction source. For guidance on the best RTK networks, contact the heliguy™ survey team by calling 0191 296 1024 or emailing survey@heliguy.com

Obtain A Trial Licence From heliguy™

If you are experiencing issues with your RTK provider, there are a few steps to try to resolve the problem. If you are unsure what mount point to use or you have any doubt over the credentials you have placed into the RC, go to your NTRIP/RTK provider for further support and information.

However, if you believe that your RTK provider is the route of the issue, the heliguy™ survey team can create a trial license for you.

As we are partnered with Premium Positioning, we have access to the Premium Positioning Portal and can create a free 14-day trial licence.

The login will consist of a username, password, server address, port number, IP address, and mountpoint.

Contact our team to help you create this account.

If the trial license does not work due to a server portal error when creating the license, you can use the heliguy™ Premium Positioning login. The credentials for this login are:

• NTRIP Host 

• Port number

• IP address

• Username

• Password

• Mountpoint

Please ask the heliguy™ survey team for these details. 

Flying Without RTK: Using A PPK Workflow

Alternatively - and if all else fails - you can fly the drone without RTK and adopt a PPK workflow.

Firstly, ensure that RTK positioning is turned off on the drone, as it will not take-off when enabled. The mapping mission and flight parameters can be left the same as if they were flying with RTK.

The positional corrections can then be applied to the drone using a PPK workflow.

This workflow is as follows:

1: On the app on your remote controller, such as Ground Station RTK or DJI Pilot 2, turn off the RTK function so that the aircraft is flying in GPS mode. The aircraft will continue to store an observation file using the positioning functionality which is used in the post-processing of the data.

2: If possible, set up the base station over a known point. This will mean that its position won’t have to be derived using post-processing methods. If you cannot set up over a known point then there are a few extra steps to follow:

a) Download a RINEX file from a local reference station that will accurately know its own position.

b) RINEX data can be found on the Ordnance Survey’s website here.

c) The base station observation file and the RINEX file from a local reference station can then be used to determine the base station’s accurate position.Now that the base station position is known, the GPS drone observations can be corrected in relation to the base observation data collected on-site.

3: The corrected drone positions can then be used to correct the image geotags stored in the EXIF data of the photos.

Can I use PPK workflows for LiDAR and Photogrammetry?

Yes, PPK workflows can be used for LiDAR and photogrammetry missions.

PPK for photogrammetry: We encourage users to sign up to a 14-day trial of RedCatch Toolbox, or to use EzSurv, to allow them to apply centimetre-level corrections to the photos back in the office. This can be used for the DJI Mavic 3 Enterprise, Phantom 4 RTK, M300/ Zenmuse P1.

PPK for LiDAR: For full details, visit heliguy™s free L1 course and watch the last 15 minutes of Module 2. This will explain the LiDAR workflow in more detail. 

For more information on PPK workflows for photogrammetry or LiDAR, please contact the surveying team.

Summary 

We hope these steps help resolve any issues you are experiencing with your custom network RTK.

If you have any further questions or need additional assistance, don't hesitate to contact us.