Deer trip it. I have it looking about 4 feet high across the driveway, so nothing smaller does. Not that many deer cross my driveway, and none during the season.
Takes a lot of intelligence to discriminate a deer from a man. Same size, same weight. The IR is looking for a heat difference from ambient moving from one zone to another (of I believe 16 zones).
Leaves and snow do not affect it.
Every spring for about 3 days, the sun is at an angle where it glares off something and causes a few nuisance alarms a day from shining into the thing.
But all I'm doing is turning on lights and starting some Pelco Spectra cameras in a scan sequence, so no harm is done from a false. It rarely falses. If someone is driving or walking in, they also hit other X10 hardwired motion sensors so I know if they're heading towards the house, the shop or the barn.
Steve
********************************************************************* Steve Uhrig, SWS Security, Maryland (USA) Mfrs of electronic surveillance equip mailto: snipped-for-privacy@swssec.com website