# Latency bug in voxl-mavlink-server

Source: https://forum.modalai.com/topic/2466/latency-bug-in-voxl-mavlink-server
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2023-07-22 03:32:34 UTC by hmlow
Replies: 5 · Views: 1147

## hmlow · 2023-07-22 03:32:34 UTC

Hi devs

I encountered this as I moved from SDK0.9.5 to SDK1.0 on the VOXL2:

* UAV and GCS (QGC) communicates over cellular, joystick only (no RC transmitter)
* Fly the UAV. Land. Replace the battery (or for testing purposes you can just sudo reboot the VOXL2)
* **Do not turn off the QGC application** (tried on both Android and Windows; with physical joysticks)
 * Upon reboot, the connection between QGC and UAV will resume. But, you will notice that the latency is say 500ms - 1s higher than usual. It becomes very apparent in flight because the joysticks' sticks movements are no longer considered "real time". You wont be able to notice it just by switching flight modes on the ground.

The workaround to restart voxl-mavlink-server (without rebooting QGC) or QGC itself **after** the connection has resumed in Step 4 above.

This issue is repeatable every time

Did not experience this in any of the earlier SDK versions.

## Reply by hmlow · 2023-07-25 01:36:39 UTC

Hi.. can any devs confirm that what I encountered was a valid bug and not smth that was unique to my setup only? Thanks

## Reply by Eric Katzfey (ModalAI staff) · 2023-07-28 20:56:55 UTC (in reply to hmlow)

@hmlow We don't normally fly with Mavlink commands. We will attempt to set up a test fixture with this and see if we can replicate the issue.

## Reply by hmlow · 2023-07-29 00:30:09 UTC (in reply to Eric Katzfey)

@Eric-Katzfey thank you very much for looking into this

## Reply by Eric Katzfey (ModalAI staff) · 2023-08-02 00:55:19 UTC (in reply to hmlow)

@hmlow Here is a link to an updated version of PX4 that should solve this issue: http://voxl-packages.modalai.com/dists/qrb5165/staging/binary-arm64/voxl-px4_1.14.0-2.0.43_arm64.deb

## Reply by hmlow · 2023-08-02 01:13:06 UTC (in reply to Eric Katzfey)

@Eric-Katzfey thanks for the 2 fixes in a single package! Will try it out and report back tmr