Hi.
I just finished constructing and testing my very DIY modem/rc receiver
using the rfm23bp (1W) and rfm22 (100mw) and they work great.
The main version is basically a rc receiver that supports a low speed (9600 or 19200 max)
transparent serial link.
It uses the RFM22 or RFM23BP which is a SPI transceiver and a AVR mega328p like the arduino pro mini or nano (3.3v 16Mhz needed) for controlling it.
The code used is ready and can be found here
https://github.com/openLRSng/openLRSngif you want the device to be used as an rc receiver AND modem (tested only at 9600bps)
and here
https://github.com/openLRSng/openLRSngDLif you want to make a modem.
Schematics etc can be found inside each rc rx or tx's directory here
https://github.com/openLRSng.
Follow th elinks inside for the wiki with instructions on how to build it, of course you can ask me if you get stuck.
The total cost of my rc receiver-modem was 20$ with parts from Ebay.
Next i will try to adapt the code in order to run inside the autopilot without the need for a
AVR mpu.
Btw i tested the 100mw Orangerx Openlrs receiver sold at Hobbyking as a rc receiver and i got error free signal 15Km away using a 6db 433 Mhz antenna.
The 1W version i build outputs 664mw at 5v which is normal because for 1W you need 6v.
Also have in mind that the 1W RFM23BP and the 100mW RFM22 modules come in 3 flavors 433, 868 and 915 Mhz so you can build whatever rc receiver or modem you like
Here are a couple photos of the receiver-modem.
20160701_153150.jpg
20160701_153209.jpg