IR Emitter

Quick question about IR emitters. What level of output(mW/sr) do I need to be able to transmit over a distance of 10m? How about 30m?

Also, how does ambient light in a room/sunlight effect IR? Would full sunlight "kill" the signal over a distance?

Would putting the emitter in a tube and using a lens make a difference?

What about wavelength? Is high better?

Thank you for the help. I always find this forum a great help.

Output level required for a given distance depends on ambient lightning, even if you use a modulated IR carrier direct sunlight will just about completely saturate an IR transistor, a well designed photo diode detector might do better but not sure by how much. Fluorescent lights can interfere with signals as well. Wavelength is mostly irrelevant. Build one and experiment with it, they're not difficult to make.

Standard IR remote controls work more then 10m, and use simple three pin receiver IC's. It's normal to pulse the emitter LED at 1A or so using a carrier frequency of about 38KHz.

I've used the TSOP series of IR detectors with good success. Vishay, I think.