# RTK (without Qgroundcontrol)

Source: https://forum.modalai.com/topic/512/rtk-without-qgroundcontrol
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2021-10-25 11:30:31 UTC by kasarrowtec
Replies: 5 · Views: 1434

## kasarrowtec · 2021-10-25 11:30:31 UTC

Hi,

We are trying to achieve RTK without Qgroundcontrol. We have a base station thats streaming RCTM messages (with a custom IOT board) to the VOXL over MQTT. The base station board has a ublox FP9 chip. 

Were a little unsure of how to approach things on the VOXL side in terms of connecting to the PX4 or just how to pump in our GPS stream. The end goal is to have RTK working independently from QGC and with our custom board.

Any suggestions or pointers will be much appreciated, thank you.

Best regards

## Reply by Eric Katzfey (ModalAI staff) · 2021-10-25 16:16:50 UTC

What interface is available on the custom IOT board? This will determine how to connect it to Voxl. For example: UART, Ethernet, etc. Once you have the board connected you will need software to convert the RTCM messages from the external board into Mavlink messages for PX4.

## Reply by kasarrowtec · 2021-10-26 08:30:47 UTC

@Eric-Katzfey said in [RTK \(without Qgroundcontrol\)](/post/2387):
>  Mavlink messages for PX4.

the custom IOT board is at the base station, not on the drone - it uses wifi/LTE to send RTK data via AWS cloud.

We get the RTCM messages from AWS via MQTT - So we are able to get the RTK data on the linux part of the voxl. Now we want to send those RTCM messages into mavlink messages to the PX4 part of the VOXL and are unsure of the software to use etc.

## Reply by Eric Katzfey (ModalAI staff) · 2021-10-26 15:04:36 UTC

Ah, okay, I see. We do have some internal example code that takes RTCM data from the Internet and sends it into PX4. Let me see if I can make that public.

## Reply by Eric Katzfey (ModalAI staff) · 2021-10-26 21:05:06 UTC

https://gitlab.com/voxl-public/flight-core-px4/px4-telemetry-proxy

## Reply by kasarrowtec · 2021-10-27 08:17:06 UTC

Thanks a lot Eric this definitely helps, will keep updated on progress.