Re: what the difference between light emitting diode&las
Hello Ronny
You want to use infrared right?
Then if u use laser u can reach up to 4-5 meters range and for LEDs this is quite smaller up to 2 meters due large beam pattern.you cant focus as well but if u use a large area receiver as well, u take more power so use APD but by this way ofcourse u will increase the input capacitance since u increase the area.
And there are also some lenses for the transmitters, search them on net. There are amplifiers both pre and back amp. used after the receivers. this shrinks the ambient noise and shot noise. But for infrared comm. u can't escape from noise, this is impossible. Best way is also to use a sector combining. Have u taken a course on mobile communications, if not just search about the max. ratio combining or best sector or equal ratio combining , then u select the best SNR and go on your way but as much as u add components u make it expensive and slower and complex so nowadays the scheme is to implement the circuit as simple as possible..This is the summary, I suggest u to use LD and APD..
Memo