Hello ,
Some friends and I are currently working on a small quadcopter that would be used mostly for photography . However , in order to get better on android programming , we really want to code an app that allows us to control the quadcopter by our smartphone . This can be easily done by using a bluetooth or wifi receptor on the quad . However , we are trying to go further than that and at the same time , expand the range :  we want our app to send a bluetooth signal to a bluetooth receptor connected to a radio transmitter (5.8Ghz or 2.4 Ghz , we haven't decided the frequency we want to use yet ) , which then , after treatment , sends the signal to the radio receptor connected to the flight controller .
I wanted to know if it's possible ? 
Thanks ! 
(If there's something you didn't understand due to my english , or due to my bad explanation, just tell me, i will try to do better ) 

Up !

It might be possible.  Here's a video from 4 years ago with a transmitter talking to an android device.  (There are links for the software, and it says there are directions for modifying the transmitter.)  You'd of course have to go the other way (Android giving commands to the Tx to transmit various stick positions.)  Good luck!

It certainly is possible. One approach would be with an Arduino that communicates via Bluetooth module. The Arduino will then encode the commands into a PPM signal which most radios can take as a trainer override (the audio jack on the back). You will have to play with an existing radio to see voltage levels etc. And best to start simple and just send values for the 4 channels from the Andriod app directly, before attempting complex commands or flight procedures. Latency will be an issue, especially if you expect responsive flights. Most FPV setups will require latency of less than 100ms. For comparison standard PPM has effective latency around 80ms, SBUS/DSMX are gunning for under 30ms.

Or you can send voltage levels directly through an hc-06 and an arduino's analog pins

Thank you all for your answers ! I will post a thread as soon as we make it work as it can be an interesting project in order to understand rc control and basic android programming !

So I coded that app , and it enables me to send a PPM signal by the jack output , associated on the movement of some virtuals joysticks : can I just plug an RX transmitter to the jack output ? I mean , by modifiying the connections of the transmitter of course .
Thanks in advance !

(08-Nov-2016, 08:48 PM)nayefmh Wrote: So I coded that app , and it enables me to send a PPM signal by the jack output , associated on the movement of some virtuals joysticks : can I just plug an RX transmitter to the jack output ? I mean , by modifiying the connections of the transmitter of course .
Thanks in advance !

Yes, as long as the radio supports trainer mode which you will also have to configure. It should be easy to confirm on the radio if the channels are overriding as expected.

Here is a good tutorial on configuring a Taranis in trainer mode. Similar videos can be found for Spektrum or Futaba.

The thing is that i want to completely ditch the controller ! I just want to transmit directly the signal from my phone to the quad . I think its possible to use a FM transmitter like the AM one used to transmit the video stream , and receive it on a receiver connected to the FC , but I need to be sure of it