Actually I have no idea why companies related in building RC electronics still haven't made such modules a reality, but may be some of you guys will?
basically, when you use UHF LRS systems, to fly lets say 10,15 or even 30 km, you have no Telemetry.
May be some of you are thinking: well, lets take a cheap PMR radio, hack the Tx module to send some data back to us where we will receive it with another PMR radio, and recode it and display it on a small liquid crystal display, it won't be reliable, wont' hop frequency but who cares it will work...."
Meanwhile, ANYONE who is flying an FPV plane as at least one free 'channel' to use for telemetry!!!!!
The audio from the video transmitter.
And if your video transmitter has stereo input for audio (microphones) you have 2 spare "channels" to use to send data back from the plane to the ground station!!!
The video transmitter on an FPV plane is already consuming so much power, and is so big and powerfull and takes so much space and weights so much and creates so much interference.
And since it is already, doing all of the above things,
why would you 
add external / 3rd party telemetry, to complicate things even further, when you can just encode telemetry data, and send it trough the audio stream back to the video receiver, when you can simply take it, decode it and display it on a screen, or into your radio trough the Trainer port may be (since the trainer ports are already made to accept audio like interface, after all you connect your radio to your sound card on your PC when using it to fly on a simulator)I really hope to see someone implement this, and even SELL such a DIY boards,
1)Video TX Telemetry data through audio encoder
2)Video RX Telemetry data rom audio decoder
3)And may be even screen????
So all you need to do is connect the encoded signal from your preferred telemetry main board, the DIY "Video TX Telemetry data-trough-audio encoder" will process it and push it into the microphone input on your TX, and all you have to do then is decode it on the Video RX side using the decoder board!!
Shove the cable into your TX, 9x or whatever, and using OpenTX/Er9x/other custom FW, you will display this data on your' radio's screen!!!
Thanx for the attention.
PS: I am not trying to say that built in telemetry (for example the FRSky) telemetry is useless. I just want to say that it is useless for LRS FPV flights where UHF radios are used most of the time, and we need an alternative.
