The Omni RTK (Real Time Kinematic) system employs a high-precision satellite navigation technique useful for accurately measuring global position with an error margin on the order of centimeters.  The following sections provide detailed instructions and guidelines for properly interpreting and collecting RTK data.

Software Prerequisites

  • OnTop™ version or later (released on April 5, 2017)
  • Double 4k firmware version 0.14.0 or later

Double 4k Update Instructions

For cameras running firmware versions prior to 0.14.0, update the device using the step-by-step procedure below.

    1. Download the firmware update file “snapcam-ota-0.14.0.zip”. (219MB)

    2.  Remove the SD card from the Double 4k camera.

    3. Copy the “snapcam-ota-0.14.0.zip” to the /firmware folder on the SD card.

    4. Insert the SD card into the camera.

    5. Power on the Omni system.

    6. The Double 4k camera will automatically reboot 2-3 times and its LED will blink rapidly while the update is being applied.

    7. Wait for the LED at the bottom of the camera to turn solid green.

    8. Power off the Omni system.

    9. Remove the SD card from the camera.

    10. View the “/info/info.txt” file on the memory card.

    11. Verify that the Filesystem Version is 0.14.0 to confirm that the update was successfully applied.

    12. Insert the SD card into the camera. The update is complete.

Viewing RTK Data in OnTop

The RTK position data is viewable in OnTop™ within the “Photo Details” window. These data fields include:

RTK Fix Type

RTK Rel. Altitude

The relative altitude from the base station RTK GPS antenna to the Omni RTK GPS antenna.

Vertical Accuracy

The estimated vertical accuracy of the RTK relative altitude, as reported by the RTK receiver.

Operation Guidelines

When used with the OnTop™ software, the Omni RTK system is designed to accurately measure, record, and display the vertical distance from the RTK base station antenna to the RTK antenna on the Omni drone for each image.  It is important to note the height of the RTK base station antenna relative to the base of the tower to compute the actual height of antennas and equipment in the images for every tower survey (see Figure 1).  

Figure 1: Example of correcting for base station offset

The horizon is a useful reference point for imposing height measurements recorded by the Omni RTK system on various components of the tower.   The height of any tower component level with the horizon is approximately equivalent to the sum of the RTK base station offset and the RTK relative altitude measurement (exemplified in Figure 2).  For optimum position data, pause and hover the Omni at a stationary point before capturing each image.

Figure 2: Example interpretation of RTK data in OnTop™

GPS Status on Video Overlay

Below, in Figure 3, the significance of each component of the RTK status overlay is detailed.

Figure 3: Details of RTK Status Overlay

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