GNSS RTK with mp2128g2

[ฺิBoonsarm Pooalai]

้hi guy

I can use external gps rtk with mp2128g2 board and then how to install it to use.

[Evan Schellenberg]

Hello Boonsarm,

The autopilot allows you to configure a UART for an external GPS receiver.

If you use a GPS receiver that supports RTK you can use our DGPS plugin to send corrections from a base GPS to the remote GPS for RTK.

We support compatible units from Ublox (for example the M8P RTK capable GPS receiver), Novatel (such as the OEM 617D or OEM 615), Trimble (such as the BD920), and more.

The DGPS plugin manual has details on setting that up for a base GPS receiver, and we have a Novatel Integration guide that covers Novatel setup that would also apply partially to other GPS types.

In summary:

Set up a UART in the Comms tab of the VRS Editor for the External GPS protocol. Configure the settings for that UART so it can communicate with your GPS receiver.

Then in the GPS tab of the VRS Editor select the GPS type you are using, the baud rate, fix rate, and other settings that you want to apply to the GPS receiver.

The airborne GPS receiver should be able to get a normal GPS lock with the autopilot when tested at this point.

Then you can configure the DGPS plugin's comm settings so it can communicate with the base GPS receiver. Lastly, configure the GPS base's position and GPS correction type to match the corrections the GPS receivers use.

When configured and connected to Horizon, the DGPS plugin will send corrections from the base GPS receiver to the remote GPS receiver through the data link. The DGPS plugin will indicate the current precision of the GPS fix.

Evan Schellenberg
MicroPilot Support

[ฺิBoonsarm Pooalai]

Hello Evan Schellenberg

Thanks for your reply my discussions now I Configure that follow in picture I attach reply. Now I want to Know how install or plug in the external GPS to MP2128g2 witch another socket or not? If you have picture about set up or install that one. Can you sent to me? 

Regards,

Bunsarm Pooalai

UAV Pilot

www.centrovision.co.th

[Evan Schellenberg]

Hello Boonsarm,

The on-board GPS receiver is not RTK capable. You will need to buy a different GPS receiver that works with one of the GPS protocols in the autopilot.
We sell Novatel GPS receivers that are RTK capable, but for other brands you will need to source your own, I've listed some models in my previous e-mail that can be used with the autopilot.

I see that your version does not have the newer Trimble BD9xx or Ublox protocols available, so you will need to renew your technical support and get a newer version of Horizon to use those. So for RTK in your current version Novatel GPS receivers are your only option in that version. I have attached the Novatel Integration guide to this e-mail which includes VRS setting images and wiring diagrams.

For the base GPS receiver, it must be configured to work with the DGPS plugin that comes with Horizon. This requires setting up the COM port, base GPS position, and correction type. I have attached the DGPS plugin manual.

Evan Schellenberg
MicroPilot Support

[ฺิBoonsarm Pooalai]

Now I have external GPS RTK receiver. It's local RTK develop by Thai People. They have parameter about this one. How can I install this one with MP 2128g2? 

[Evan Schellenberg]

Hello Boonsarm,

You may be able to get basic functionality out of the M8 GPS receiver in your version of Horizon, but it will be lacking many features such as multi-constellation support and DGPS corrections. So RTK likely won't work as the DGPS plugin would not have the correction format needed.

You would need to use 3.7.1088.0 or newer to have full functionality of that GPS receiver.

To try using it as is, connect it as described in my summary above, you will have to define a UART in the autopilot's VRS and connect the two TPU lines you use to the GPS receiver with 3.3VTTL to RS-232 converter in between.
That board indicates it outputs at serial levels, since the autopilot's TPU lines are 3.3V level you must use a converter or the TPU lines will be permanently broken.

One the UART's Tx and Rx are safely connected to the GPS receiver Tx and Rx you must connect a third TPU line to the PPS signal on the GPS receiver. I do not see any PPS pins indicated on the interface board pictured so it may not be routed out. In that case you would have to find which pin has the PPS signal on the GPS receiver and attach a wire to it. If the PPS signal is 3.3V it ca be connected directly to the TPU. If it is >3.3V then you must reduce the voltage level of the signal.

PPS is required to use an external GPS receiver so if you cannot access the PPS signal you won't be able to successfully use this GPS receiver with the autopilot regardless of software version.

Then configure the GPS tab to see if you can get the GPS receiver to lock. But note it may not work in your version, I suggest regaining access to the support site and getting a newer Horizon version.

[ฺิBoonsarm Pooalai]

Hello Evan Schellenberg

I can connect RTK to MP2128g2 already, but the RTCM signal from this RTK is RTCM3. I read in the manual of MP that support only RTCM2, I can modify the program of MP2128g2 and Horizon 3.7.1088.0 or newer. How to download it?

Now the horizon sees the RTK base and RTCM signal, but only the RX can not send the TX to the mp2128g2 board. The RTCM3 signal is being modified to the RTCM2 version, then try again.

Thank you for your advice

[Evan Schellenberg]

Hello Boonsarm,

To use RTK with the M8 and other newer models of the Ublox receivers you would need a newer version of Horizon. Then you can get the latest NMEA and Ublox protocols in the autopilot and the latest DGPS plugin correction types.

You can contact [e-mail] to talk to someone about renewing extended technical support which will renew support site access.

Evan Schellenberg

Micropilot Support

[ฺิBoonsarm Pooalai]

Hello Evan Schellenberg

Thank you for your information