Good to see this discussion of Seismic Intrusion Detectors. Since I've been using these for the last 20 years I thought I'd pass along some of my experiences with the systems and devices. First, the AN/PSR-1A:
I got my first one at a gun show after looking high and low for them. The seller had no idea what it was. The previous owner had left the D cells in it until it corroded. It came with the original four sensors plus another 14. Super neat. With a good set of batteries and holders it's worked like a champ ever since. Sure it takes commo wire but so what. The nicest thing about it is with a small 9 volt DC radio shack amplifier and a clip lead you simply clip onto the leads showing the indication and you can not only hear stuff, you can listen to conversations. It's that good. [Here is a real life example:] You should have heard whatever it was that was eating the deer it took down and NO, I didn't go down there until morning.
Secondly, the AN/TSR-3A Wireless Seismic Intrusion Detection Set:
I originally got a set of these neat RF (read wireless) units for peace of mind while camping and then bought more as I ran across individual units. Daily, I use one in each vehicle as a wireless alarm, set to the minimum sensitivity and with the sensor horizontal (which is the least sensitive position). If the car even moves a little or even a fingernail tap on the window, the 2 meter on my belt beeps merrily away and I can be as far as a mile or two away from the vehicle. They come as a set of four on one of six frequencies (I think it's 6) so I acquired mine on three different frequencies.
Between the different frequencies and the fact that they each beep out 1,2,3 or 4 beeps, each with a different tone, I readily know where the action is.
BTW, "Springmtnd" was dead on regarding Merino Wool! It's great (and,
now, newly acquired) ... Thanks!
Regards to you and the Memsahib.- The Army Aviator
Have you checked out "Dakota Alert"? (See: http://www.dakotaalert.com) Intrusion detection is their specialty. - S.A.M.
JWR Replies: The Dakota Alert sensors are far more reliable than those Chinese junk systems that you typically see on eBay. You pay more for quality.