Not many people know but we have an piece of open source software for controlling an Antenna Tracker. It's been built by Tridge (Arduplane lead developer) for use in the outback challenge.
Sadly we have no documentation and, as far as I know, nobody except Tridge has used it. Still given Tridge's track record on building great software I suspect it works well and if it doesn't, I'm sure we can fix it. So to not let this piece of code go to waste, I'd like some help from people who are interested to give it a try and help me figure out how it works.
Here's the little that I know:
- It runs on any of our supported board (APM1, APM2, PX4, Pixhawk, Flymaple and perhaps VRBrain)
- For APM1/APM2 users building the code is as easy as opening our hacked ArduinoIDE and selecting File > SketchBook > Tools > AntennaTracker and then building in the normal way. For PX4/Pixhawk, our autobuilder doesn't automatically build a binary but I can provide one if people are interested.
- It can control a Pan and Tilt gimbal like this or this found on servocity.com.
- It may or may not require a GPS
- It must somehow receive vehicle position updates from the ground station which has the telemetry radio that is connected to the vehicle. Maybe through a USB cable. Tridge probably uses the python ground station, MAVProxy, to passthrough the vehicle position data to the AT but perhaps we can get MichaelO to build out a similar feature in Mission Planner.
- I imagine this antenna tracker could also be used to keep a camera focused on the vehicle which might be good for easing the burden on creating videos of our vehicles.
So if you want to give it a try please do and stick any findings, questions or issues below. Alternatively Issues can go into the issues list.
I'll start sticking things into the wiki as they become clear.
Replies
FSK modems are not radios, they are just modems, to transmit/receive they use Audio channel of your Vtx/Vrx
telemetry modules are only needed if you intend on flying automissions, for pure fpv fun they are not used at all. On some of my models I use DTF UHF gear (copters) due to low alt and behind trees, but fixed wing I fly on 2.4ghz band with a 2W amplifier on taranis (with 9LR Rx the furthest I went was about 4.8km) I usually fly max 1-3km, but around myself so my 5.8ghz patch needs to be pointed at the craft all the time, and this is really inconvenient and this is why I need AT. Since we already have audio channel (often stereo = 2x channels) why not utilize it, especially since it costs about $3.50 per FSK modem?
Even with full telemetry setup, it would be a nice security measure to have redundant GPS/Altitude info, especially for 2x$3.50
Interesting info, thx. I should experiment these audio modems.
another one: if you fly multiple craft you have to make sure that each of air modules has the same "bind ID" as the module on the ground, so you can't really fly them simultaneously.
This is a good idea - most "off the shelf" antenna trackers use either teletext data or audio channel data. It would be nice if our firmware could work this way.
Provided that you supply a proper hardware (TX modem and RX modem) the implementation into AT firmware should be easy if not trivial (audio RX can output a fake mavlink frame into AT)
modems are very easy and dirt cheap to make even when ordering boards from non-commercial board manufacturers such as oshpark. for about $20 one can make at least 6 modems. Those will work at 2400baud, so we just need to very carefully select SRx values, set baud to 2400 and make sure that AT is in "listen only" mode. But since mavlink is actually a rather big and complicated protocol I suggest using LTM
https://github.com/kh4/FSK_modem https://oshpark.com/shared_projects/KhuRuKNW
https://www.dropbox.com/s/n315ybsf1p2nnxg/FSKv2%20assembly.pdf
this is better to use data feed inside RC link like in UltimateLRS and it's works really well.
http://www.itluxembourg.lu/site/ultimate-lrs-wiring-diagram/
and dedicated forum here :
http://www.rcgroups.com/forums/showthread.php?t=2037442
UltimateLRS, This what I use to get long range telemetry on a budget and it works perfect with orange TX modules (default antenna need to be replaced by more reliable ones, I use diy dipoles). I recommend it too!
try gitsly brunch of openlrs NG, has 57k mavlink support and works on all hardware including dtf/uhf and Flytron (HK Orange)
https://github.com/gitsly/openLRSng
It doesn't support quality hardware like DTF UHF, I've had enough with HK orange crap. (RF dirty when works, two modules I used were making my sat count on 3DR lea6h drop 2-3 satellites worse than a lawmate 1w vtx (verified 978mw) on 1200mhz within 7" from GPS) For comparison 1w DTFUHF Rx (870mw) has 0 effect on the same GPS at the same place with the same antenna and every single of the total 3 Tx units and 10+ Rx worked right away without issues.
Ideally I would just write a lua scrip for taranis to control two servos :) based on telemetry from FRSKY telemetry of openlrsng which I get natively from pixhawk.
It's a shame that flipflap doesn't want to comply with GNU license, otherwise someone would've ported it to DTF UHF hardware (order of magnitude better than HK orange)
It does support DTF UHF in version 2; Orange TX 1 watt modules were shown cleaner in their RF emissions than some much more expensive brands, see rcmodelreviews ad flip flap own web site; these modules emit at 400mW when fed with 3,3V and closer to one watt when fed with 6V. And finally flipflap complies fully with GNU and released his source code.
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