Many people have had excellent luck with Ubiquiti products. Keep in mind over that distance you'll have a fairly large fresnel zone, so you need a really clear line of sight.
The Nanostations will cover that range, but you *might* want to just step up to the NanoBeam units.
Given that it's an IP camera, the image is generally going to be an all-or-nothing scenario. You'll either have a solid link and get back a nice video stream, or you'll have a crappy link and will get either no image, or an extremely smeary/degraded image.
Yeah I'd second Brian's opinion. I'd look for something with a narrower beamwidth than the NanoStations for that range. The NanoBeam should do.
IPVMU Certified | 11/26/13 09:04pm
matthew we do several installations using ubiquiti products... we have never had a three mile throw however... (did a 7 mile using another manufacturers hardware)... i would encourage you to use the advice below and the ubnt forum as well... some great advice on their regarding topics like yours... if there isn't one start one and it will be answered in no time...