Apologies in advance if this is the wrong sub-forum. In the past I built two copters with standard telemetry radios (one 3DR clone and one mRo). I am contemplating a third one under 250g (ideally a lot under), and would like to understand where I can compromise to save weight. One obvious target for me seems to be the telemetry radio, which is pretty large and bulky… Is it possible to fly a Copter with a sufficiently capable FC/autopilot but without a standalone telemetry radio connected? If it is, what would I lose in terms of copter functionality? Thanks.
Telemetry is usually more a tool for the pilot to provide helpful information and possible warnings during the flight.
It also allows direct control of certain functions like camera gimbal, auxiliary servos,manual parachute release,…
One further function is to use special features like the “follow me” option, guided flight modes (I.e. clicking on a map in MP and having drone flying there),… and RTK correction for precision GPS use in some limited circumstances.
If you have a very reliable drone / FC and you don’t need any of those features/functions, then you could fly without any telemetry radio.
I’ve got an older drone that I sometimes get out just for a bit of fun and I don’t bother with telemetry when flying that particular one.
However, also have to admit that I did get caught out in the past where I intended to do just a little fun flight or testing some change I’ve made and then run into problems and in one case lost a drone due to fly away. In such an unfortunate event I would have preferred to have the additional data and information available that a telemetry link can provide.
Also if you use a transmitter and receiver capable of running the Yaapu telemetry you wonder what you ever did without it
you could use crossfire and get telemetry mavlink to be exact and it has come a long ways and works “pretty” well now. I keep reading and getting bits and pieces here and there that elrs will possibly have some sort of bi-directional mavlinkish or even mavlink in the future. when and if that happens there will be no reason for anything else. mro has a pretty light weight wifi module that works well but depends on your range needs. if you have no needs for it don’t add it or add something like ELRS or crossfire that has the possibility now or near future. crossfire can be a bit clunky but it works for my quad so do the wifi modules on the pixracers. under 250g will be fun with ardu I have tried a few but gave up and put them back on BF as I could not get them tuned for the life of me!
Yaapunis awesome for unidirectional telemetry to the transmitter. It’ll callout audible mode changes, alerts, etc.
You might want a small/light short range bidirectional telemetry link, if only to change settings without plugging in a cable.
If that’s all that is required an ESP8266 radio works well and are very cheap. I have them on several models for that purpose. They will fit on anything.
Since it’s ardupilot, I would really love to be able to retain the ability to point-and-fly using a tablet and QGC/MP/DP. Otherwise my KISS- or FETTEC-based FPV quads are much more enjoyable to fly when there’s no need for a map or 2-way telemetry. I see there are some Bluetooth and WiFi devices that can also be used for telemetry, some of which seem smaller than the mRo radios, but they also seem to have very limited range.
Since Crossfire and ELRS have very long range, I am wondering whether it’s possible to somehow hijack part of that data link for mavlink (or some reduced mavlink) data packets so that the AP can tunnel all telemetry directly through the radio link instead of pushing it via a dedicated telemetry link. @406FPV , how would this work though? How can my mobile device see the incoming packets tunneled through the radio link since it operates outside of that link? Is some additional device, or maybe bluetooth from the RC transmitter to the mobile device, required to route the mavlink data back and forth between TX and mobile GCS?
ELRS does not have any mavlink functionality “yet” but I hope in the future it may I was following a cpl PR’s that addressed that but lost track of them. Crossfire on the other hand already supports mavlink telemetry and you can set it up that way with mavlink rx/tx pin instead of having them set to crsf tx/rx through the lua agent scripts. then using the module in my radio I connect to the wifi hotspot and boom telemetry 57600 to whatever is connected to the crossfire wifi address. Although its not as polished as one would think it works.
How well does this work? TBS was such a mess with this that I put it aside for a future release.
What still doesn’t quite click for me, @406FPV, is the last part – how does the TX connect to the mobile GCS? The video above refers to a “router IP address” – do these two need to be connected to the same Wifi network, i.e. within mere meters of your home? Will this connection prevent the mobile GCS from connecting to a different wifi hotspot (which is how I get internet connectivity on the mobile GCS in the field)?
The Yaapu scripts work well with ELRS. But that’s still just unidirectional. It’s a great way to monitor things without the need for extra hardware in the field.
I have successfully used this bi-directional wifi module on a 5" copter. The limit is the wifi range.
I also used yaapu (very useful) on my arducopter sub 250, but of course it’s unidirectional
This looks cool. But let me make sure I understand correctly. With the JMT wifi module onboard, telemetry is transmitted via 2.4GHz Wifi, so the GCS needs to connect to the wifi network “AlphaUAVLink” from the JMT module in order for MP or QGroundControl to be able to see the data stream. I think this also means that the GCS cannot connect to a different wifi hotspot to also get internet access… So it can either connect to the telemetry stream, or to the internet, but not both at the same time. Is that right? If that’s the case, while very cool, this solution unfortunately won’t work for me because I need the web to access maps real time.
Dude, a computer based GCS and an RC transmitter are two entirely different technologies with different functionalities, strengths, weaknesses and purposes that operate on two different frequency bands and use different data transmission and reception protocols. The only way I can think of to get what you want is to add a joystick to your GCS computer: Joystick/Gamepad — Copter documentation
I use a smartphone mounted on the radio, so I have the WiFi connection for telemetry and 4G data connection for maps that can still be downloaded before the flight always via the QGRoundControl GCS
@oldgazer1 Thanks man. Been in the hobby since 2012, flying FPV since 2014 and autonomous missions with AP since 2020, so I can confidently say I understand the difference between TXs and GCSs :). What I am looking to understand is how to use both for complementary control of the copter while using the least amount of hardware possible on the copter itself. What @Alberto_Ds mentioned is a good solution.
- Another theoretical solution I can think of is tunneling mavlink data through the crossfire/elrs RX and having the TX serve as a bluetooth device that a GCS can connect to in order to access the mavlink stream. Sounds like this hasn’t been implemented (yet).
- Yet another theoretical solution I can think of would be to bypass the need for a GCS altogether and have a skinny version of QGC or MP ported to run straight on the TX, like yaapu does today, but implementing bidirectional mavlink, while also possibly connecting to a wifi hotspot for real time maps. This doesn’t yet exist either.
- Yet another possible solution would be to have a TX module that can do both RC control and mavlink data link, both communicating with a single RX device on the copter instead of two. But even then, to properly see what’s going on and interact live with the copter, the GCS would still need to connect to the TX module ideally via bluetooth. And I am not sure that exists today either (at least not yet).
Update: in fact, it looks like the third possible solution above may already have been implemented. I have just found this module+RX, which seem to be doing exactly what I described. Whether it actually works reliably is another story… I have read mixed reports.
SIYI FM30 Radio Module 2.4G Transmitter with Bluetooth Long Range Mavlink Telemetry Datalink Mini Receiver Support OpenTX EdgeTX ExpressLRS Yaapu Script 30KM Range
The SIYI modules definitely work, and the SBus relay is functional. I find it a bit clunky because you still need to use an RC receiver connected to the ground unit (or wired SBus out), but it does work. The range estimates are a little overblown in my opinion, but most of my testing has had a lot of ground interference, so perhaps I’m not the best source of range info.
EDIT: I have not used the JR bay module so cannot attest to its performance. I’ve been using their video/telemetry setup marketed as the “HM30.” It’s a nice rig.