I have 2 sets of Radiometrix RX2 / TX2 sets which have RSSI and can communicate up to 200m at 9600bps
I'm looking at getting a radio dialogue between the 2 prototypes, i.e. creating a protocol for messaging with hooks that a RX unit would recognise, then ensuring the correct sync so that the RX unit can read the data sent by the TX unit. Because there is no 2-way communication, the sync cannot be negotiated so needs to be a listening process.
The programming wouldn’t be hard, Netduino would use c#, Arduino would use C, pic would use Pic-C
I have experience with similar projects and it is easily realized by applying the appropriate algorithm. The details will be agreed during the implementation until you are completely satisfied.