Security Idea

[koossa]

Good day Picers.

We're living in an high crime area inside a security complex.
Our main problem is that the perpetrators are still entering our complex by cutting the razor wire and climbing over the walls.

Does anyone know of a relatively inexpensive way that we can pickup if someone is trying to enter the security complex.

The distance around the complex is about 2 km.

Any ideas would be much appreciated!!

Thank you

[Jumper]

Hi,

A couple of IR-led with proper lenses and some receivers would make a simple fens. If you put them close enough lets say every 50m you can easily detect if anyone breaks the beam and connected with RS-485 you can indicate what section it is done.

Lasers would work too but are more difficult to modulate and would require better adjustments. A quite wide IR beam along the top of the fence and the receiover in a pipe to give som direction and shadow.

I guess landmines is not an option here

[koossa]

Hi Jumper

Thank you for your reply.

How far will the IR-LED detect someone and will I be able to go 2km with RS485?

[Acetronics2]

Hi, Koossa

Dogs, Lions, crocodiles moat, Geese ...

but Cheap technology won't make it for a 6 to 8 Km long fence ...

Alain

[Jumper]

To start with you would only need to get 1000 m range of the RS-485. That is of course if you put the main controller in the middle of the 2000 m fence :-)

And with a low baudrate you can get up to 4km I think... so this should not be an issue.

When it comes to IR led a normal TSAL6100 can be modulated with i.e 40kHz to get a carrier that fits a normal TSOP4140. You can of course have any carrier fq but 33k 40k and 57k are common. Then you send data on this carrier in short burst. Short enhough to be able to drive the led really hard 500mA or something and short enough so you don't overheat it.

A good guess would be that intruders are more common during night time than daytime and so getting 50m is not that hard. After 50m there is a receiver and a new LED and so on.

If you would like to try a normal magnifying glass attached at the end of a pipe is a good start. To get 50 m you would need a 25-50mm diameter and a focal length of atleast 150mm to make it work during daytime.

If you need more info you can PM me

[Melanie]

Buy a Dog or two ... and I don't mean a Pekinese or a Poodle either!

IR Beams can easilly go for 100m or more... but are tricky to set up... the professional one's are best because they have vernier adjustment on the mirrors... a fraction of a degree at 100m or more means you miss alignment on the target.

Try running a voltage through the razor wire (a few kV would do)... PIC can then detect if it's been cut.

[koossa]

Hi Jumper

Thank you very much for your feedback!


Melanie, I like the "power through the razor wire" idea, but the only problem is how do I detect which zone it has been cut?

[Jumper]

With enough kW there would be smoke from the person cutting the wire...

[mister_e]

Or the local skateboard shop will increase sales

[koossa]

How difficult is it to communicate over a 50m IR connection?

[Ioannis]

I have an IR pair for over 100m made with 12F series PIC. Sorry I cannot publish the code as this is a commercial product. But for 2Km, you may need many pairs.

PM me for any more infos.

Ioannis