Electronic Alarms and Home Security Devices - I've got a motion detector acting odd!

I have a 16 year old Napco Magnum Alert system (model 1008 LKDL). I really need it to sense traffic across a walkway about 40 ft. from the motion detector. The original Napco detector would not trip the alarm consistently. Sometimes it would work, sometimes it wouldn't work during testing. I purchased and installed a new Rokonet motion detector and it does the exact same thing - inconsistently sets off the alarm.

Any ideas?

40 feet is pushing the reliable range of even the units that claim "long range". Once you get out that far, the detection pattern is pretty spread out.

There are a few detector models that do better at longer distances, but they tend to be a bit "industrial" looking.

Also, it depends on if the motion is directly in line with the detection pattern or crossing it. Basically, if the traffic is moving directly toward the sensor, your detection pattern is less effective.

MrRonFL,

Thank you for your response. I estimated the distance at 40 ft., but in measuring it accurately, it is 35 ft. The specifications in the manual claim a range of 50 ft. Should it work consistently at 35 ft.?

Also, the detector has a jumper setting for "pulses." Off equals no pulse count, and On equals "Alternate Polarity Pulse Count (2 Pulses)." Since I need detection at the 35 ft. distance, which jumper setting should I use?

I repeat, the detection pattern spreads out (look at your installation instructions). The more sensitive setting would be the "no pulse count" setting. Basically those lines on the diagram represent the lines of infrared that the device "sees" with. To trigger an alarm, a body has to break more than one. Reducing the "pulse count" reduces the number of lines that have to be broken.

Compare the detection pattern on your install instructions to the area you are viewing. Things the cross the pattern are more likely to generate an alarm than things that move in line with the pattern.