1. Graupner MX-20. Supports a lot of channels. Allows to mix multiple receivers. Great for FPV and multiwiicopter. ppm. Expensive >400
2. Futaba has 12 channel systems or more. ppm. Very expensive >500
3. Hitec Aurora 9. 9 channels. Supports telemetry. ppm. 391
4. Turnigy 9x. 8 channels. No ppm with included receiver. Transmiter has internal ppm. Open source firmware. Extremely cheap! ~ 50

1. Using included receiver and a ppm module we can control multiwiicopter. ~ 25
2. Replacing receiver with frfly system. Telemetry. Supports multiple receivers but not at the same time (http://www.frsky-rc.com/uploadfile/201009/20100930115814373.pdf). Clame 1.5Km range. (look in hobby king. http://www.rcgroups.com/forums/showthread.php?t=1408118&page=2). ~ 100
3. FrSky. PPM!! 4-channel has 8 ppm channels. http://www.multiwii.com/forum/viewtopic.php?f=16&t=944
4. FrSky. d8r-II with cppm: http://www.youtube.com/watch?v=_lkjfvyUGg8 http://www.rc-heli.de/board/showthread.php?t=189318 http://www.frsky-rc.com/download.asp?id=23
5. FrSky. Conversion! http://www.youtube.com/watch?v=DHnV6hGH108&feature=related
6. FrSky. DIY module : http://www.frsky-rc.com/ShowProducts.asp?id=85
7. Replacing receiver with jeti duplex system. Supports all 16 channel with mikrokopter receiver, or 8-channels with the normal ones plus Supports multiple receivers. Not clear is the range (uses xigbee inside, maybe small range) 300-400 meters (http://forum.mikrokopter.de/topic-22404.html). A lot of telemetry data. (look in mikrokopter. http://www.mikrokopter.de/ucwiki/JetiDuplex, https://www.mikrocontroller.com/index.php?main_page=product_info&cPath=108&products_id=599, https://www.mikrocontroller.com/index.php?main_page=index&cPath=108) ~ 200
8. It's possible to modify turnigy to accept ppm-in signals to add another turnigy or a FPV headtracker. (a resistor)
9. LCD backlight mod is almost necessary.
10. Turnigy mod, using frSky FJT. http://www.daddyhobby.com/forum/showthread.php?t=67760
11. Guía español: http://www.aeromodelismovirtual.com/showthread.php?p=172718

We can use the turnigy 9x/flysky th9x to learn to fly in linux.

• Download and compile crrcsim
• Disconnect transmitter module from 9x and connect audio cable to 9x and to mic or line-in input in your PC
• Run crrcsim and configure it to use the audio signal as input device. Then calibrate device.

• I used the diagrams from here: http://code.google.com/p/th9x/wiki/installation_de to create a programming cable.
• I bought MySmartUSB light programming usb key from here: http://shop.myavr.com/index.php?sp=article.sp.php&artID=200006
• I use eepe to flash the device: If you use debian sid I recommend to not use the debian packages from eepe, but to recompile:
  • Go to eepe-read-only/src
  • qmake-qt4 -r
  • make
  • ./eepe
  • Go to burn→ configure
  • Fix the path of the avrdude executable
  • Set programmer to stk500 (works with MySmartUSB light programmer by default)
  • MCU= m64
  • Port= (empty)
  • Extra Arguments= -P /dev/ttyUSB0 (or your corresponding device, look in kernel messages when you connect the USB programmer)
• Get your hex file from er9x (if you have the frsky modification use er9x-frsky.hex file)
• Write flash memory and select the previous file.
• Done!

The FrSky telemetry module has a rs232 port on the back. This port has RS232 voltage levels (~12V), which is incompatible with the AVR microcontroller inside the 9x. We need to make a level converter. We could use a maxim 232 IC to do this but in several places in internet is not recommended because it requires you to disconnect this converter while you are programming the AVR. Instead we follow the guide here : http://code.google.com/p/gruvin9x/wiki/FrskyInterfacing . With this circuit everything works fine! Also, it's compatible with er9x firmware.

To compile with frsky mods and without the templates and heli menus:

make EXT=FRSKY TEMPLATES=NO HELI=NO

Then use eepe to upload flash and eeprom

http://uracoli.nongnu.org/