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Follow Me - Tethering to another device

Discussion in 'Pro/Adv Discussion' started by Mako79, Sep 16, 2015.

  1. Mako79

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    The follow-me system isn't perfect - yet. Follow me works by following the GPS in the smart/phone device. The only draw back is the device is physically connected to the remote and therefore visible when followed. The solution is to wireless "tether" the GPS data to another device.

    I have briefly tested 3 methods:
    1. Litchi and Magic Leash (Android only).
    2. Go App and Holux 236 External Bluetooth GPS
    3. Go App and additional Android device - BEST!

    All 3 methods work but have limitations.

    1. Litchi and Magic Leash.
    Difficulty - 2 ninjas.
    Litchi Magic Leash - Android Apps on Google Play
    I tested this on 2 android Lollipop samsung Note4 devices. Litchi pilot app cost $15 and the Magic Leash is free. Litchi is android only and Magic leash is android (and soon to be released IOS).
    I won't go into detail with the Litchi as there is threads already. Magic leash works by connecting to a server. This is paired by a unique random 4 pin number. It requires 3G/4G data services.

    Pros:
    • excellent range (limitless provided you have data).
    • light and easy app to setup on android phone.
    Cons:
    • Requires data network.
    • Average 300-400ms lag.
    • Litchi is not free.
    2. Go App and Holux 236 External GPS (you can use any external Bluetooth gps).

    [​IMG]

    Difficulty - 4.5 ninjas.
    Using a class 2 External Bluetooth GPS device required some tinkering.
    You need a Bluetooth GPS app installed on your phone and you need to enable Mock Locations in the USB debugging mode.
    Bluetooth GPS - Android Apps on Google Play
    The app will force/trick the phone to use an external GPS.

    Pros:
    • No data plan is required and works anywhere with an open sky.
    • No lag. (The lag is with the DJI GO app resetting home point).
    Cons:
    • Cost about $50-$100
    • Poor range. Device is a class 2, range is 10m (33ft)

    3. Go App and additional Android device.
    Difficulty - 3 ninjas.
    This is my favourite option. Its a little confusing at first.
    Using an app called TetherGPS (lite version has 5 min sessions and dies after 200min, get the full for $2). The TetherGPS app simply sends GPS data via the wifi.
    TetherGPS Lite - Android Apps on Google Play
    I used a throw away android phone as the secondary-followed-device (no data or sim required). Both android devices will require "Hotspot and tethering" via wifi.
    Install the TetherGPS app on both devices.
    Start the wifi hotspot on the secondary device that will be followed. Start the TetherGPS and click Start Server.
    Now on the device connected to the controller, connect to the wifi hotspot. Start the TetherGPS and click Start Client.

    Pros:
    • No lag (except by the goapp)
    • Use anywhere.
    • Est 50-70m range (depending on wifi interference)
    • No data plan required on followed device.
    • TetherGPS cost $2 (im sure there are other free apps, I like to support devs).

    Cons:
    • If the followed device does not have data, then please cache map first.
    Mobizen screen record demo of follow-me. Apologies for the screen size as the mobizen on default messed up the orientation.
     
    #1 Mako79, Sep 16, 2015
    Last edited: Sep 17, 2015
    tcope and Oso like this.
  2. Oso

    Oso

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    This is good stuff. Thanks so much for doing these tests and posting your results. I'm very surprised that this thread didn't go viral. It makes me want to buy a couple of android devices to do option 3.
     
  3. tcope

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    When you say Litchi is limitless, what does this mean? I guess it refers to the two devices as they are connected via data. However, the device connected to the controller and the controller would like need to maintain a connection with the P3. That would mean that the controller and device need to stay fairly close to the leash device (a mile or so at the most).
     
  4. Kaehn

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    Litchi Magic Leash is limited to RC range, that will always be the maximum possible range. Compared to other solutions, it can be considered limitless.
    Also would like to point out that the lag with Litchi will depend on where you are. Sydney is quite far from our NYC server, I personally get 100-150ms from the UK.
     
  5. Timbooo

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    @Kaehn
    Are they (litchi) not using peer to peer to peer communication after the initial connection is setup and the devices are paired?
    Or is all communication routed through their servers?
     
  6. Kaehn

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    All communication is routed through a server
     
  7. Timbooo

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    Is it not possible to just use the server for initial connection, and use p2p until any of the two devices loose connection?
    That would certainly decrease latency.

    Or are you doing heavy serverside calculations?
     
  8. Kaehn

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    Internet P2P in the mobile world isn't as easy as it sounds.
     
  9. Timbooo

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    Read into it. Seems to add a lot of complexity. I guess I would get about the same latency as you from Sweden.
    What is the total round trip time when the Magic leach phone changes position, until the phantom responds?
     
  10. Kaehn

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    It's about 100-150ms where I tested it (UK). When I last tested it, the phone GPS would update about every second.
     
  11. Mako79

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    Does the sdk let you increase the refresh rate? The home point updates are too slow.
     
  12. Kaehn

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    Litchi's follow mode does not use DJI's follow implementation, I am not sure what you're refering to for the home point as it is not used in Litchi's follow mode. You can however have the home point continuously update to match your current location using the Dynamic Homepoint general setting which is generally a good thing to do in Follow mode (updates are every 2second).
     
  13. zebra

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    Hello Mako79,

    for the Litchi solution is required a Phantom3 Advanced or Professional or Phantom2 Vision/Vision+, not supported on Standard because of a lack in the sdk.

    Do you know if go app + external gps or secondary device works also on Phantom Standard?

    Thanks