Mavlink bandwidth usage

Simple question, how do I know what over the air data rate (and over the wire baud rates) to pick for my RF telemetry link to ensure I have enough bandwidth for the refresh rates I have picked for the various streams ?

Have read with ECC switched off the air rate to baud rate throughput is about 90%, and with it switched on this is about 50%. So this tells me how to scale air rate to baud rate. But how do I ensure I pick a high enough rate to start with ? And what about GPS Injecton or adding in the RC signals as the RFD868x allows you to do ?

Is there a rule of thumb for how much link margin you loose when increasing your data rate ? For instance does doubling the over the air data rate loose you 3dB of link margin ?

I can find a few people asking this question but the answers are generally very vauge, such as:!topic/mavlink/H5yqm3NxMJ4

I have also tried asking RFDesigns but so far 3-4 emails (on different subjects) have yeilded zero response. Fairly unimpressed with them. I can theorize the bandwidth the RC signals consume. 11bit/2048 resolution (0.5us resolution over 1000us) on 8 channels, with a 22.5ms frame rate gives, 11 x 8 x 45 = 3960 bps but there are a lot of assumptions there.


Use this tool that is specifically designed for that:

This is part of pymavlink. Please download the entire pymavlink repository in order to use it.

Currently only works for ArduCopter, but it is easy to expand. Pull requests are welcome.

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Bloody brilliant. Thank you. Looks like it’s support evaluation of GPS_Inject as well.


Yes it is supported, but you should tweek it according to your configuration.

Do you mean tweek the GPS Injection aspect of the script or just tweek the script in general as it is targeted at Arducopter currently ?

No need to change the script. Just need to change the GPS_RTCM message stream rate in the GUI, so that it matches the expected bits/s

Perfect, thanks for all the help, and writing the script to !

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