Minimize latency on 3DR radios used to spoof GPS

I’ve currently disabled the GPS on my APM and I’m sending GPS packets to the vehicle using a 3DR radio (V1). The GPS data is getting to the vehicle and being decoded/used correctly but I’m a little concerned about latency. Basically, I have almost no idea what the end-to-end latency looks like for the 3DR radios (overall latency and consistency of latency). I noticed that the radio configurations default to use MavLink framing.

  1. I was wondering if disabling MavLink framing on the radio would reduce or increase latency or have an effect on the consistency of latency?
  2. Also, are there any specs on the 3DR Radio latency (i.e delay induced for packaging/transmission/un-packaging)?

Also, if you have any suggestions about how to minimize latency over the 3DR radios I’d definitely appreciate it.


Hi duster3,

Here you can find the technical information about the 3DR telemetry radio: … m-and-px4/

[quote=“RogelioN”]Hi duster3,

Here you can find the technical information about the 3DR telemetry radio: … m-and-px4/[/quote]

Thanks for the reply RogelioN.

I’ve walked through that documentation but it doesn’t address any specifics as to latency. It does mention a low latency mode for MavLink frames but doesn’t really talk about what “low” is (looking for a range in milliseconds). It also doesn’t mention any details on the effects of disabling mavlink framing.

Hi duster3.
I am trying to do the similar thing as you did, using 3DR radios to simulate ublox GPS signals for PixHawk. I am struggling with the latency now. Did you measure the latency with equipment like signal analyzer before? If you did, would you mind to share the data with me? Thank you!

OK. Can a noob ask a noob question? If removing the gps increases latency, why would you even want to remove the GPS?