security system

[mdtest]

Looking to place a security system on a large rural piece of property. Looking to build sensors around the xbee chip. This property has people crossing barb-wired fences and coming up near the house. Camera's have been placed but I want to create sensors that are motion detecting or trip/wire like that will record the date and time. The idea is to find where the folks are crossing the fence and then move a remote camera near there. Any suggestions for sensors that are picaxe friendly would be helpfull. The property is nearly 200 acres so a mix of permenent and portable sensors would be best. Xbee will give the flexability of many remote locations.

Thanks

 

[hax]

I like the thought of a laser beam circling the property. With the pickup and the laser coming from the house itself. Therefore no requirement of external electronics or power supplies.

With careful alignment, it should work over a good distance. Are there any fixed objects you could mount mirrors to? They need to be very fixed so that alignment over time is not an issue.

 

[mdtest]

Near the house there are many trees. The property has 7 buildings on it counting the house. The entire property has a perimeter fence, so there are many fence post. 1 requirement is to be able to narrow down the where the fence is being breached. Can your idea of a central laser beam pin-point the breached area?

Md

 

[BeanieBots]

You can get "off the shelf" RF security systems quite cheaply. I bought one a few years ago because it was cheap way of getting half a dozen RF Tx units complete with encoder chips. It included four RF PIR sensors.

Your PICAXE could then check the zone LEDs on the Rx unit.

 

[papaof2]

You may be able to use Xbee hardware, but you should do range tests before committing to *any* RF solution.

Set up an Xbee at the most distant point from the location you plan to have the monitoring station. Have a PICAXE connected to the Xbee and programmed to send a number every few seconds (incrementing from 1 up). Verify that the Xbee at the monitoring location receives every message.

Then you could set up multiple Xbees with PIR or other detectors to monitor selected sections of the fence. Have the PICAXE on each Xbee report in with its number and "OK" every 10 minutes or so. If motion is detected, the unit would report in with its number and "ALERT". If a remote fails to report in, the remote unit could have a low battery or it could have been stolen or damaged - if the latter, you know at least one place the fence is being breached.

John

 

[mdtest]

I should mention that just one length of the fence is over 4000' long, thats 1 side of the property. That would take a lot of XBEE's & PIRs. I've been researching the Flooby's geophone concept in an array that I found in another thread. The only problem there is there is cattle on the property.

It stands to reason, if someone is going to enter the property, they will either climb the 5 wire barbwire fence or cut the wire. I plan to experiment with a strain gage on a couple of wires. To date noone has cut any wires. I've crossed some barbwire fences while hunting and I've always put a foot on middle wire when doing so. This should provide enough strain on the wire even though it is tacked down on each fence post. A strain gage ever 100' could narrow down the breach.

mdtest

 

[Jeremy Leach]

I wonder if you could add another wire to the top of your fence posts, as in my rough drawing attached (!). This wire would be free to move, through a loosely hammered in U shaped tack. The wire would be fixed to one post, then run say 500' through many posts to a spring tensioner. At the tensioner is a picaxe unit with a microswitch to detect if the wire has been depressed, with radio link etc. So have a unit every 500', all communicating with a central unit.

OR, another cunning idea ...
Instead of many picaxe units, just have the microswitch and a resistor at the tensioner. Wired as per ....

                 o
                 |
                 |
                 |
                 |
                 |
              .--o--.
              |     |
           \  o    .-.
            \      | |
             \.    | | Unique resistor value
  Microswitch o    '-'
              |     |
              '--o--'
 Normally closed |
                 |
                 |
                 o

The wire itself with these microswitch/resistor combinations form a complete circuit around your property. Make each resistor a unique value. Have just one Picaxe unit in your house that reads the resistance of the circuit via an ADC input.

Because each resistor is unique value, and is only brought in circuit if the wire is depressed, it should be possible to pinpoint the sector that is being breached !

Ok, I can see possible issues with the inbuilt resistance of the long long wire circuit, plus pickup of noise etc - but it might just work. Plus would possibly be a lot cheaper?? (cost of picaxe 08M, piezo buzzer , serial display and box <£20, cost of 5 miles of wire £100+ LOL!)