On Sat, 13 Mar 2004 23:50:38 +0100, Omega Software wrote: >>> Andrea wrote... >>>> For the receiver I'm thinking about using a small telescope, pointing >>>> it to the transmitter (hopefully 1+ Km away.. ehm). Will the lens be >>>> transparent for the incoming 875nM or 950nM light? >> >> Surely at that sort of range you would be better going with an RF >> solution >> no? At those sort of distances atmospheric scattering, dust, fog & heat >> lens effects will be tremendously problematic. > > I reckon that pure pulses would violate all EMI laws on the planet, and > thus are to be avoided.. but a tuned system shouldn't be illegal > (provided > that the use of that frequency isn't illegal as well.. and that, ok, one > obtains a licence to transmit at such high power levels, even for short > bursts O;-) ). > > Back on the frequency selection issue.. any idea? Why not pop down to your local computer store and pick up a pair of 802.11b wireless networking cards and make or buy a pair of directonal antenna's for them (2.4 GHz ISM Band), assuming you have line of sight more or less it is perfectly possible to accieve stable links of several miles with sensible (Megabit) data rates, or if your appliaction is not computer related, a pair of wireless video senders that also happen to operate on the same band - that way all the EMI is taken care of. Regards Alex -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.