I am part of a project looking into creating a telemetry system using an Arduino. I would like to transmit data gathered by the Arduino on the 70cm band back to our ground station (yes I do have my ham radio license... however this is my first project trying to build my own Tx system).
The data to be transmitted would come from a sensor network and GPS, also connected to the same Arduino. I would like the data transfer rate to be as fast as the Arduino is capable of. My current thoughts are to tackle this using PWM on the Arduino Mega to act as my frequency modulation, using a digital-to-analog converter to change the output of the Arduino to AC, boosting this output up to the level I need with an op-amp, and then building my own tuned circuit to achieve the correct impedance with the antenna I have.
As far as using RF systems for Arduino that already exist, I have read about the XBEE products for RF, however we're looking for a system that has more range than even the 900Hz chip they have, which as far as I've read is the lowest frequency Tx available from them. If there are any products available that can integrate with Arduino easily and can use the 70cm band, I would love to hear about them!
Do you think my approach is feasible? If anyone has experience trying to create this type of system, what difficulties did you have? If it helps, this telemetry system is intended for high powered rocketry applications.
Please let me know if more clarification is needed. Thanks.