[url]http://www.hi-vel.com/Catalog__15/Perimeter_Alarm_Systems/perimeter_alarm_systems.html[/url]

Looking at this:

HV-2 LOUD WHISTLE TYPE
VERY SIMILAR TO THE HV-1 IN CONFIGURATION EXCEPT THIS UNIT EMITS AN EAR-PIERCING SCREAM FOR APPROXIMATELY 3 SECONDS.
SUPPLIED THE SAME AS THE HV-1. CAUTION: FOR OUTDOOR USE ONLY AWAY FROM FLAMMABLE MATERIALS.

I have two fields with two gates. This time of year, I don't lock the gates so the folks baling hay to get in and out at their convenience.  The problem is, some people will drive up, open the gate and drive in with truck, trailer and ATVs and start riding--"we didn't know it was nobody's land!", or just come in and steal hay.

I would like something that 1. I can hear for about 1/2-3/4 of a mile away and go check or kinda scare someone AT the gate and make them think about entering. Do not want to hurt anyone, just to alert me at night or warn them when I am not there.

Any comments, suggestions, concerns?
Thanks

I think the blanks have promise. They have no hazmat fee and you could potentially load your own to save money. I'm thinking a few grains of Bullseye under a small plug of greatstuff foam or a cork plug.

Of course you are on your own trying to reload blanks. I am just typing out loud here.

Maybe something with parachute flares and some kind of report.   This will help light up the sky as well.

frisco

btt
thanks for the repies.

A company SHOMER-TEC  www.shomer-tec.com sells a 12 gauge gate alarm, plus you could load it pointing up with bird bombs, they would go off in the direction you point the device and explode with a pop about 100' in the air. Then there are IR alarms , but you get a lot of false alarms with rodents, and other animal forms of life.Lord Henry Enterprises Inc. sells them but there pricey 350.00 and up range depends on line of sight up to 1/2 mile, with portable units you can carry that will signal you also. Then there are others but the price goes way up, semi professional seismic sensors etc., there cost prohibitive.