Hi,
I’m an engineer working in the aerospace avionic industry, but I’m also an experienced old style model aircraft enthusiast, not flying anymore since about 10 years. I’m stuck with the classic PWM radio style and my current radio is an old fashioned 35Mhz crystal Graupner.
I’m trying to catch up with the latest technology and use ardupilot on one of my old aircrafts.
I’m really confused about the radio communication. As far as I understood there is the possibility to use the RC radio to carry both the RC radio data itself and also data from the ground station. Same for downlink (see diagram).
- Is this actually possible with the available RC radios on the market?
- Are there limitations or criticality (other then redundancy) to do this?
- How the connection between the RC radio and the laptop is usually made?
I tried to search in the forum but similar topics are old and probably outdated.
Thank you so much
Adriano
ExpressLRS has a feature in development called mavlink-rc that does exactly that:
There is also mLRS (GitHub - olliw42/mLRS: 2.4 GHz & 915/868 MHz & 433 MHz/70 cm LoRa based telemetry and radio link for remote controlled vehicles) which is a bit more DIY at this point but support for ELRS hardware is coming along.
As these projects are in active development, the best place to get up-to-date info and setup help are their respective Discord servers:
ELRS: ExpressLRS Community
mLRS: mLRS
A bidirectional RC link does sound easiest, but it is a little problematic in practice and usually not the recommended path (at present).
If you just want telemetry down, you can use ExpressLRS and the Yaapu telemetry script on a compatible ExpressLRS transmitter (like Radiomaster TX16S, among others). Lots of discussion here and on GitHub about that script and its configuration.
For full bidirectional MAVLink comms, I recommend SiK radios that operate separately from the RC rig. Information is available in the ArduPilot wiki.
The experimental features from ExpressLRS are promising but probably not ready for prime time, and will still require a Bluetooth or serial connection to a GCS computer to take full advantage.
mLRS is “neat” but I hesitate to call it easy to configure. Though some may disagree, I would consider mLRS to be superseded by ExpressLRS’s own features (including AirPort, which is again, probably not the easiest path and requires an additional TX/RX pair).
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Thanks both,
I understood that expressLRF and mLRS are a bit tricky. I will go with the basic standalone wifi telemetry.
Thanks again
I think the top line tbs module can do it and also there is the Australian company that sells modules ( name completely escapes me now ) and they had one option that did it also, but other than those two systems everything else required two parallel comms paths
mLRS is well optimised and works on a lot of hardware now including most of the express LRS receivers. I have used both MLRS and ExpressLRS mavlink and the expressLRS implementation has a long way to go before i could use it daily. It lacks some critical features like it cannot do any telemetry on the handset other than link stats, so no yapuu lua script as express LRS usually gets that from the flight controller, mlrs converts it from mavlink so it still works.
mLRS at 19hz mode with frsky r9m it gets 1550 bytes/s
express LRS mavlink gets 1250bytes/s
expressLRS airport gets 500 bytes/s
neither are simple if your not familiar with modern radios
I have personally never had any luck with the SIK radios, the 433mhz versions were junk due to the usb chip jamming them, the newer versions like the hollybro might be better but they are very expensive.
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