I want to build an FM transmitter that will transmit (on an unused frequency) from my laptop (near my video projector) to my receiver (about 20' away on the other side of the room). Then, I thought wouldn't it be cool to transmit music to the bedroom...again about 20' but with a wall in between. And of course, how about the workshop? about 1500sf, completely open.
How do I determine the signal strength that will meet these requirements:
- maximum transmission distance perhaps 50-75' sometimes with a wall or two, but mostly without, but
- weak enough to fall within FCC regulations for an unregulated xmitter.
I'd hate to solder something together that only transmits 5'.
Given a transmission distance, how do I calculate the power? does the power requirement change with frequency (e.g., 88.1mHz needs less/more power than 107.1mHz to transmit the same distance. Is there a rule of thumb for factoring in walls between trx and rx? or is that negligible?