PRISM: Here+ RTK Base & Tripod Combo
The Here+ Base & Tripod Combo allows users to have a plug and play RTK experience for positional RTK with PRISM and the EchoSky Mobile radio system.
This product is available for purchase HERE.
Assembly:
Install the double sided locking tape onto the back of the EchoSky Mobile Radio system.
Attach the Here+ Base onto the back of the EchoSky Mobile radio and attach the cable to the Here+ base via the 5 Pin JST white connector.
Plug in the USB plug into the back of the EchoSky Mobile radio.
Attach the antenna & mount to the tripod using the 1/4-20" threaded screw.
Connect the antenna to the back of the Etlas Mobile Radio system.
Congrats, the Here+ base RTK system is ready to go!
Achieving an RTK Lock
Now, simply open up WattsQGC. The WattsQGC app will automatically detect the RTK system. This is shown on the top right of the screen, with the RTK symbol now shown.
When the RTK symbol is red in color, this means that the RTK system is currently looking to achieve a RTK Float or RTK Fixed position. By default settings in WattsQGC, the RTK must wait for at least 3 minutes and achieve an accuracy of 2m (6.56').
Once the RTK system has achieved an accuracy of at least 2m and it has "cooked" for at least 3 minutes, the RTK symbol will now turn black in color to indicate that has achieved at least an RTK float position lock.
Note: Click the GPS Status button to see the type of GPS Lock.
Types of GPS Status Lock:
3DGPS: The system has achieved a 3D GPS status, but has not yet achieved RTK lock (least accurate)
RTK Float: The system has achieved a floating point RTK solution (accurate)
RTK Fixed: The system has achieved a fixed RTK solution (most accurate)
Advanced RTK Settings
If your use case requires different settings than stock or if you wish to use a specified base position, simply navigate to the General Settings menu in WattsQGC and scroll down to the RTK GPS portion. Here you will be able to modify these settings.
Perform Survey-In
Survey-in accuracy (U-blox only): The minimum position accuracy for the RTK Survey-In process to complete.
Minimum observation duration: The minimum time that will be taken for the RTK Survey-in process.
Use Specified Base Position
Base Position Latitude: Latitude of fixed RTK base station.
Base Position Longitude: Longitude of fixed RTK base station.
Base Position Alt (WGS94): Altitude of fixed RTK base station.
Base Position Accuracy: Accuracy of base station position information.
Save Current Base Position (button): Press to copy settings from the last Survey-In operation to the Use Specified Base Position fields above.
The Survey-In process is a startup procedure required by RTK GPS systems to get an accurate estimate of the base station position. The process takes measurements over time, leading to increasing position accuracy. Both of the setting conditions must met for the Survey-in process to complete. For more information see GPS- How it works (ArduPilot docs).
In order to save and reuse a base position (because Survey-In is time consuming!) perform Survey-In once, select Use Specified Base Position and press Save Current Base Position to copy in the values for the last survey. The values will then persist across QGC reboots until they are changed.
RTK FAQ:
Q: Do I need to do anything to the aircraft for the RTK system to work?
A: No, PRISM is RTK ready from the factory. All that is needed is a base station, such as this one.
Q: What is the accuracy of the Here+ RTK System?
A: The Here+ RTK system is capable of achieving up to 1cm accuracy under ideal conditions. Based on our testing, this may take anywhere from 10 minutes to 2 hours for the RTK system to achieve an RTK Fixed position, where this 1cm accuracy is noticeable.
Q: How is this RTK system best used?
A: We recommend using this RTK system simply for more accurate flight path following and to keep the aircraft more "locked in" during flight. This RTK system should be considered as a "positional" RTK system, only to keep the aircraft more locked into a fixed position in space. This system has not been used for survey grade mapping or surveying.
Q: Does the pilot have to stand next to the base station tripod during the flight?
A: Yes, because the antenna is connected to the Here+ base station, which is connected to the radio, the pilot must stand next to the base station during the entire flight. The cord is approximately 10' long, which does provide some freedom of movement during flight.
Utilizing a Second GCS as a RTK Base Station
There are certain applications where users may wish to use a second communication link (Such as an RFD 900X) and a second Ground Control Station (such as a PC Laptop running Mission Planner or WattsQGC) to initiate the RTK lock. This will then allow the pilot to use the EchoSky Mobile out in the field, whereas the second GCS is mounted in a fixed location such as under a tent or in a vehicle, with the Antenna having a clear view to the sky.
For this application, simply open up the second GCS's software (such as Mission Planner), and connect to the RFD900X or whatever link is connected. Then go into Setup -> Optional Hardware -> RTK Inject. Then, choose the COM Port of the RTK device, and click Connect. This will then initiate the connection with the RTK module and the vehicle is now beginning to get RTK lock.
On the main screen of Mission Planner, the RTK status can be shown as seen below in the photo.
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