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
Very cool. Almost makes me want to build one...:-)
Good job here!
To be honest, I find an antenna tracker to be an unnecessary complexity. If one is flying close in, use circular polarized antennas and if long range, even a Yagi has enough beam width to point it manually. Tridge is using an extremely high gain antenna so it may be warranted but if you ask me, that is an exception.
I'm very happy to see this development. I like the idea of repurposing older APMs for new uses.
What sensors are used? I have some defective units and I'm wondering if I can make them work.
IMO, unless you are mapping very large "lawnmower" runs, close in, you are better off with a BiQuad antenna. Almost the same gain as a small Yagi but the beam width is broader.
Further, the costs of larger servos and P&T assemblies with bearings is fairly steep. Then add the field set up time and calibration.
Not trying to rain on anyone's parade, just passing on a bit of been there done that, knowledge.
Btw, the airborne GPS is used in conjunction with MAVLink messages embedded in the telemetry to provide the GPS location of the plane. The tracker takes that data and points the antenna accordingly to the correct azimuth and elevation.
Steven,
Do you have any links to those types of antennas? As a minimum I'd like to add that info to the wiki's telemetry section here.
Hi Randy,
Although I was referring to a video down link and using a BiQuad, the same would apply for a Telemetry down link.
There are three links, two for a ready made BiQuad and one for building your own (DIY)
http://www.readymaderc.com/store/index.php?main_page=product_info&a...
http://www.readymaderc.com/store/index.php?main_page=product_info&a...
http://www.rcgroups.com/forums/showthread.php?t=1328260
Hope this helps,
Steven
Steven,
Thanks for that, I'll add it to the wiki. Coincidentally I have exactly the same antenna as the top one you've linked to although I haven't tried it yet. It's true that it's got something like a 52 degree beam meaning you don't have to be too accurate to get good distance.
QUESTION:
Using antenna tracker and simple servo with gear for 360 degrees of pan. What will happen while the pan servo reaches 360 degree and the airplane continue to circle around? Does the servo will turn quickly to 0 and start to follow the airplane again?
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