Would I be possible in theory to turn the Particle Photon into a make shift radio transmitter using one of the Photon’s PWM pins?
I think it’d just be a matter of how fast you can write to the pin. Using the DAC pins I’ve been able to read/write at 16 Khz and higher. So if you had an antenna / another module reading with a similar antenna, you might be able to transmit / receive. The photon runs at 120Mhz, so I would think we could probably get that read/write speed higher.
Obviously make sure you respect all local laws regarding radio transmissions and reserved channels ( http://www.arrl.org/getting-licensed ) , and maybe build a faraday cage ( https://en.wikipedia.org/wiki/Faraday_cage ) while testing!