Alternate Transmitter/Telmetry scheme...

Long ago in a galaxy far far away I built an RC solar plane.

http://www.rasdoc.com/splinter/solar2004.htm

I have a lot of switching power electronics on this plane and it was before 2.4Ghz radios were common. The power electronics caused interphereence with both 50 and 72Mhz RC transmitters.

So I made a system where I replaced the module on the back of my JR transmitter with a little CPU that read the PPM signal and used a maxstream 900Mhz radio to talk to the plane.

The plane could also send down telemetry on the same channel.

Today I see a lont of work being done to add telmetry to things like the custom turnigy 9x builds etc... yet they still use two radio systems, a (usually) bi-directional telmetry system and a separate RC transmitter.

So my question is this  why not modify the Turnigy so it sends serial commands containing all the info normmaly used in a PPM signal via a serial conenction via a xbee (either 2.4G or 900M version) and have the quadcopter autopilot use that as both telemetry and  RC communication?

Then roll the APM pllaner info into the Turnigy and have a simpler system with more capability and less parts?

I spent the evening digging through all the turnigy 9x modifcationt hreads on the net and conceptuall this seems like a simpler solution that what a lot of people are doing with two complete radio systems?

If you switch to 900Mhz bi directional telmetry/controll channel, you'll get longer range than 2.4G and also open your self up to using the really low cost 2.4Ghz wireless video systems?

Any thoughts?

Paul

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ModeratorPermalink Reply by John Church on December 18, 2011 at 11:46pm

Take a stab at it! Last Friday I went the complete opposite direction and flew without an RC Tx. I tried out the joystick only functionality of Mission Planner on my APM1 quad using APC220 modems. Using a Logitech 3d pro joystick, there are enough buttons to set every AC2 mode available. The whole flying experience with a joystick was interesting, to say the least.  :)

Permalink Reply by Maki, Eric J on December 21, 2011 at 6:26pm

Very cool idea.  I wanted to do the same thing- 1transmitter, 1reciever, ALL the data in/out.  My concern was bandwidth in the Xbee system.  I am using the 2.4gHz turnigy 9x too, 900mHz Xbee, and will use the new 1.3gHz for FPV and photos.  I'd love to be able to integrate all of these into one system.  I don't have alot of radio expertise- enough to be dangerous as it were.  Where to start? I have almost nothing to offer but enthusiasm. 

Permalink Reply by Brad Smith on February 24, 2012 at 3:35pm

i read somewhere there was too much latency with the xbees for RC control but i know I've seen it done i think it was on Lynxmotion http://www.lynxmotion.net/

Permalink Reply by Eraser on December 22, 2011 at 3:33pm

I am doing something similar with USB flight controllers and a little industrial PC on the ground connected to a 900MHz radio and in the air coming out of the 900mhz radio via serial to a micro which converts my data stream to PPM.  I wanted to use a mod5270 onboard but I have a hell of a time coding the easy stuff as it is.  I am using the same radio for video, as they also have Ethernet, with good results.


ModeratorPermalink Reply by Monroe on January 22, 2012 at 1:30am

Why not just use the 9x! The 9x and the Frsky are the same. The Frsky has telemetry down now all we need is an uplink mod for the RX! Why not go that route? It is a slow link but what the hey I think it would solve this issue? Or at least be useful!

Monroe

Permalink Reply by Brad Smith on February 24, 2012 at 3:46pm

with your own tx you could add more switches and place them too your liking and have telemetry and or use a wii controller we kinda already have that with the MP but have to depend on windows (scary)   


ModeratorPermalink Reply by Monroe on February 24, 2012 at 4:11pm

Yeah, that's where we are heading. I just don't know exactly how we are going to do it yet! I think it will happen soon where we can do remote control get video and telemetry. It's just not quite here yet. It's something we all want though.


ModeratorPermalink Reply by Monroe on February 24, 2012 at 4:23pm

I think because we have the code for the 9x we might be able to do something with that transmitter that will get us a step closer. What I'm talking about is a "cheap" solution. And a faster solution rather than a whole new system. We need two-way telemetry and radio control. Then we only need the video on a separate transmitter. Maybe we can do the uplink via the transmitter and the downlink via the audio channel of the video? And save bandwidth?

Permalink Reply by arashi on February 24, 2012 at 4:43pm

I am using the Flyton LRS 433 mhz long range module and RX with my Turnigy 9x.  You can configure the RX to send a transparent low baud rate serial link along with the PPM signal.

http://diydrones.com/profiles/blogs/openlrs-firmware1-10-with-trans...

details

http://forum.flytron.com/viewtopic.php?f=7&t=294

I want to either loose the xbees or RC transmitter.  I need to try the joystick mode through the xbees.


ModeratorPermalink Reply by Monroe on February 24, 2012 at 5:04pm

Arashi

  Do I understand correctly that you have two-way telemetry and radio control with this set up? and you are using it with APM? And if so what is the baudrate? I dont care if it's slow I just need to know if this works with the APM because if it does this would work for a high altitude drop from a balloon. Yjr reason being that with two way connection we can control the launch from the balloon manually and control the platform manually in the even automatic systems fail and this is a big issue with the FAA we could solve those issues if this really works. 


ModeratorPermalink Reply by Monroe on February 24, 2012 at 5:17pm

If that works then you could add a bluetooth to the turnigy 9x to your laptop and use Mission Planner or the Turnigy to fly either way. Correct? That way you can use a joystick or whatever connected to your pc and have both!

Can this be done? !!!!!

Permalink Reply by arashi on February 24, 2012 at 5:50pm

I don't think the 17bytes/sec transparent uplink would be fast enough to use the joystick mode.  I fear that it would add too much latency to make manual control possible.  What it does allow you to do is send commands to the APM, such as nav points, rtl, land, etc.

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