I am thinking about creating a new design for transceiving audio over a range of a couple of meters. The criteria are as follows:
- Up to four audio sources each of which must hear all of the other three stations. (Headset-microphone-earphone) Although I'm not ruling out any scheme, what I think would work is a "base station" that could be mounted somewhere in the vehicle, receive up to four separate frequencies, and retransmit the detected audio over a common transmit channel.
- Fairly high electromagnetic intensity environment ... tens of watts of RF at 120-140 MHz. at a meter or so range. Hundreds of peak power watts (average 5 watts or so) at 1 GHz. also at a meter or so.
- Entirely possible that in some instances the device will have to operate in direct sunlight. I'd prefer not to use opto techniques.
- Whatever the technology and power source, the device will have to be worn on the head for several hours at a time. It may be possible to mount the device on the chair the person is sitting on but I'd like to keep my option open to mount the whole works inside the individual headset.
- Moderately high noise environment made a little more liveable by the use of noise-cancelling microphones.
- If at all possible, I'd like something that will work in an amateur radio band...the device will only be marketed with proof of amateur license.
2 meters might work, as would 220 or 440. 220 is so quiet that I'd really like to operate in that band if possible.
I'm not so much looking at a design per se, but more a technology or device(s) that I could research and see what is available and preferable. Comments appreciated.
Jim