Telemetry Streaming and Logging

Ground Control Software MAVLink
1

Hey there. Im new at this and have few questions to get me pointed in the right direction.

I want to stream my Telemetry to my PC. (i assume the logfile grows as you fly) Im using ardupilot at the moment, and Im trying to figure out how to do this in mission planner. I saw in PX4/qgc its a simple check box, but in ardupilot I need to add a module to Mavproxy. Im not using mavproxy (i think?) so whats the method in mission planner?

second, since i have some logs already, is it possible to convert .bin to .ulog? or am I better served just changing the firmware to get one or the other?

lastly, I want to stream the telemetry to third party software. This is done with mavlink forwarding and is available in MP and QGC? is that correct?

Thanks for your help and clarification. Im just trying to level set on what the capabilties are so i know where to point my learning efforts.

2

Hello there!

When you write “stream my logs”, are you referring to the .BIN file which is recorded onto the SD card in the autopilot? If so, then you cannot really stream it live in-flight unless you have a really good radio connection with high baud rate, because the recording frequency of the sensors is usually 400 Hz.

Here is the relevant Ardupilot documentation: “Depending on the autopilot type and configuration, the dataflash logs may be saved on a SD card, dataflash chip or streamed over MAVLink telemetry ports. The MAVLink option does require a high-speed telemetry port, typically 921600 baud.”
https://ardupilot.org/copter/docs/common-downloading-and-analyzing-data-logs-in-mission-planner.html

Alternatively,you can view and transfer the telemetry data (i.e. the same data content as the telemetry log - *.TLOG that you can find and play back in Mission Planner also) via the MAVLink forwarding option, but that has a lower refresh frequency. This can be viewed in MP and QGcontrol as well.

Nemo

3

Im sorry, I mean “stream my telemetry.” i mistyped. Yes I was talking about the same data that comes from the sd card. i am a little confused though, especially by the 921600 baud comment. I don’t need the full rate telemetry stream, a 4hz refresh rate is good enough for what I need.

I am using 2.4ghz rx/tx, and working on a higher wattage rx solution. so I can use 1000hz. (range is not a major issue for me, bandwidth is)

I think I need clarification on how the telemetry works. I don’t understand the difference between the bin file and t log. the sik radios use mavlink, so i thought with elrs, it would just send that same telemetry data over the rc link at 2.4hz instead of the sik 915mhz. no extra antenna. is it not that simple?

im guessing these are basic questions, I just am not understanding how this works.

this is what i used as my primary reference
https://ardupilot.org/mavproxy/docs/modules/dataflash_logger.html

4

https://ardupilot.org/copter/docs/common-logs.html

I don’t think you can get a full telemetry stream to Mission Planner or QGC and your RC link on the same single ELRS receiver. There is ELRS Airport, but that requires two RX and two TX to work.

If you just want to see your important numbers in flight then depending on the radio you have check out Yaapu Telemetry script. Don’t get scared off by the name Frsky, it works on pretty much any EdgeTX radio, and a few others.

5

Maybe i am asking the wrong Question.

When flying with elrs I’m able to see telemetry on the qgc screen. That data is all i want. It’s already. Being passed to qgc from the rc to laptop wireless link. Is THAT specific data considered the tlog, and is it possible to forward THAT specific data using mavlink forward?

7

Still not clear what you’re looking for but I see two things:

Mission planner will automatically create a tlog. That link I provided in my previous post will explain that. A .tlog is just that, a log of the telemetry data. Better than nothing, but generally not used for analysis or troubleshooting.

If you want to forward the mavlink data to another device or application then you can also do that: Mission Planner Advanced Tools — Mission Planner documentation

8

OK that clarifies for me how the telemetry display works. Originally I thought that all of the data was streamed in parallel to the sd card and over the air. I thought the Tlog was just a seperate file descriptor to help differentiate.

I do need to forward the mavlink data, but the reason I need to forward it is because I need to inject additional commands to the drone (from a pi), and then record that data over the ota link for processing by a software on the ground station. This is whats going to allow me to see how the code in the pi is handling its job while I make adjustments on the ground.

I will read the documentation and see if that’s an option. I feel like i have read so much documentation the last few days but everytime I turn around theres more! and somethign I hadnt read before. I probably just need to read it all front to back.

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