A proximity alarm is any alarm that goes off when some event occurs within a certain proximity(distance) of the detector. The majority of proximity alarms are motion sensors. Alarms may alert only you, or they may alert both you and the intruder. It may be advantageous to alert the intruders, to give them pause before going further. The noise may also be utilized to shock the intruders for a moment, creating a tactical advantage. This may also be a disadvantage as it could cause them to become more aggressive or hostile.
Some proximity alarms are wireless and can be transported easily. When you bug out you may not be able to take a fixed alarm system with you; there are several vendors that use the unlicensed MURS radio standard and make portable units. As long as you have the ability to recharge the batteries you can use this system anywhere. The image below is of a Dakota Alert wireless system which includes a hand-held receiver for the alerts and communication with other team members. You may add many motion sensors with this particular system with a maximum of 4 zone alert tones. There are many other systems available from other vendors that may offer different and possibly better features.
While the range is claimed to be 4 miles, the reality is that it is likely to be 1-2 miles range, which is still impressive for a portable motion sensor. This is largely due to the power limitations on the MURS frequency allocation, so other units should be similar in performance. You may be able to increase the range with a homebrew antenna
If you were unable to obtain a pre-made motion sensor that you can take with you if you bug out, you can construct one out of improvised components. The biggest thing that you need is something that will make noise.
These methods are generally inferior to some of the higher tech methods, however, they are better than nothing and some can be quite sophisticated.
This method will create a loud crunching sound, easily giving away the position of the invading group or person. This method has the disadvantage of only covering a small area, usually a foot path. If you can create a choke point in the ingress path to your location, most will use that allowing this method to work.
- corrugated aluminum siding (the wavy kind)
- cover material (leaves, sod, etc)
Place the rocks as far apart as possible, with the fewest rocks possible, so that the aluminum siding is suspended above the ground. Cover the material with the lightest materials possible so it blends with the surrounding area. The heavier the materials, the less sound is created. The cover material cannot be hard, you need each footstep to bend the aluminum siding underneath.
As someone walks across this, the aluminum siding will bend and create a loud sound. Each footstep will cause more sound to occur. This sound will generally startle horses, as well as surprise human types.
This method will create a loud crashing sound, easily giving away the position of the intruder(s). This method can cover a larger area, but can be detected and defeated by skilled operators. If installed well, it can be an excellent alarm system to either alert you or alert you and startle the invaders.
- many aluminum cans
- string or tripwire
Tie as many aluminum cans as you can to a string. For added sound you may place a small pebble in each can. Then either tie the string into a tripwire with the cans suspended in the air. Proper tripwires will drop the cans when the string tension changes. The more cans you use the louder the crash will be. If these are placed outside you may experience problems with the wind blowing, to correct for this, add a couple more pebbles. If you add too many you will not be able to hear the cans, and a net around the cans may be required instead of just tying them to the string.
An alternate installation is to place the end of the string into a door jam, such that when the door is closed the cans are suspended. When the door is opened the string is released, gravity takes over and the cans fall. This method can be used to create a noise where people are not (such as outside), which will normally cause the invader to turn towards the noise, and away from you and your loved ones giving you a slight advantage for a brief moment.
If you place these in strategic spots and have control over which string will be released from a central location, you can herd cats.