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Antenna tracker for Vision+

Discussion in 'Phantom 2 Vision + Discussion' started by Cooter3690, Dec 2, 2014.

  1. Cooter3690

    Oct 9, 2014
    Likes Received:
    Has anyone figured out a way to use their long range directional antennas on a tripod with a servo controlled tracker to keep the antennas pointed at the phantom at all times? I'd be interested in this but it seems that all antenna trackers out there require a separate osd and video transmitter. Some home made trackers use RSSI but I don't think that route would work for the Vision+ either. Any ideas?
  2. varmint

    Feb 5, 2014
    Likes Received:
    Hillsboro, OR
    One of my favorite topics.

    In order to extract telemetry for tracking there are several options (perhaps more). The first 2 are now obsolete thanks to the Phantom SDK.

    1) Grab it from the repeater, decode it, and send it to an Arduino which in-turn controls the tracker. This would all take place at the ground-end with no need to fly any gear. Cons: Difficult to crack the protocols, but much less so on Android, where a lot of work has been done in other areas. It may even be possible to have a modified version of the DJI app, send the telemetry via something like Bluetooth to the Arduino controlling the tracker.

    2) Place an Arduino on the Phantom which grabs the telemetry data directly from the GPS cable, and then beams it back via an X-bee to a ground station Adruino which in turn controls the tracker. The GPS data stream has already been decrypted and the source is available on Github.

    3) Much easier, much cheaper and much lighter solution: Use the new DJI SDK to simply read the telemetry from an app and then beam the telemetry to the tracker's Arduino via Bluetooth & Mavlink. Nothing to fly on the bird whatsoever.
    This approach is why I would never buy a Flytrex. It's a waste of weight and money to fly something on the Phantom, when you can simply read it from the ground courtesy of DJI, for free.

    This also means Flytrex will need to change their model to a software solution or they're going to die on the vine because of the SDK. There is no point in flying expensive, heavy telemetry hardware once some apps start popping up. These apps can just as easily (if not more), upload live telemetry to any server in the world, and could even steam live flight video.
  3. Nathan Carter

    Oct 29, 2014
    Likes Received:
    San Francisco
    Until your Phantom goes out of WiFi range, then you can forget all the telemetry. No data anymore for pointing the antenna...

    At least Flytrex 3G provides you with a separate channel(GSM network) to your Phantom which does not depend on distance from you. And therefore actually, data provided from the Flytrex system could be much easier used for the tracking system!

    Admittedly I never looked into this antenna tracking problem before, but I would try something like the following.
    Range extender that sits on your remote has OpenWRT software running and therefore it is easy to get WiFi signal strength from it. I would put that extender unit separately from the remote, on the tripod with servos for pointing the antenna. The Arduino board(or Raspberry Pi) that controls the servos would have a wifi module and would also connect to the range extender(your phone/tablet is already connected to it, there is nothing preventing multiple connections). I would make a program to get WiFi signal strength from OpenWRT on the extender and I would make the servos constantly move left,right,up,down by small amount, monitoring if with each move the signal gets better or worse. If it is better I would stay a that new position, if it is worse I would move to the old position. This would be a continuous loop.
    As for your control signal from the RC(the 5.8GHz one) I would simply look at what direction the WiFi antenna is pointing and manually point/orient the RC antenna in the same direction.

    The SDK idea is fine, but only good untill you have steady WiFi connection. As soon as that connection breaks, anything can happen and you can easily lose your Phantom. Also the SDK is actually(at this point) at a bit high level(in a bad way). That means there is no fiddling with low level stuff for configuration. For example you can't change the WiFi network setup(how it connects, IP addresses and similar stuff), that means when you connect to your Phantom you lose any internet connectivity. No possibility for streaming any info on the net. That is why Flytrex still has a coolness factor to it, because it can do that.