Temporary alarm

[Norcon]

Is it possible to have a temporary lash up alarm operated from a battery source that would send an alarm signal about 800m over a hill from the site to the owners home?

When the timber first went to site the farmer did nightly patrols between 12.00am and 4.00am armed only with his shotgun. Obviously he didn't get much sleep.
We had the diesel siphoned from our digger so far and the battery stole and are now expecting the big one.
Thanks.

Edit.
After some googling I found this.....
http://www.ultrasecuredirect.com/acatalog/SB_Solar_Powered_Perimeter_Alarm.html

Looks just the ticket. What do you think?

 

[Workers]

Better a speech dialler than SMS.
The ranges in that advert are for the detection distances
in a straight line. That will only detect from one side of the property too. You would need 4 sets to cover around the area.
There are smaller items that could be used with a large leisure battery and solar power.
More cost effective for a temp "lash up".

 

[Norcon]

Would a wireless alarm signal repeater transmitter of the same wave length boost the signal enough to trigger the alarm on the receiver?

 

[Workers]

Not sure what you mean?
Is it to extend the beams distances? If so no.
You would go back to back with another pair to exceed those stated or find one that works longer. But, mist and fog will affect them probably. Maybe other methods of ground/perimeter detection should be considered.

 

[Norcon]

Is it to extend the beams distances

No. Extend the 900m range. Or give it more oomph to get over the hill and overcome harsh propagation conditions limiting practical operation range.

What does this do......
http://wisehouse.co.uk/signal-booster-range-expander-repeater-433

I might buy some of this stuff and experiment with it over long distances.

 

[bernardgreen]

What does this do......
http://wisehouse.co.uk/signal-booster-range-expander-repeater-433[/QUOTE]
It looks like it receives a message, stores it until the radio channel is clear and then transmits it.

Might work if there is only one of them in the system. But if there are two or more you will have problem.

Sensor sends a message,

First repeater receives it from sensor and then re-transmits it.

Second repeater receives it from first repeater and then re-transmits it.

and so on along the chain of repeaters until the end station receives it. Looks good

BUT the first repeater will receive the message for a second time when the second repeater transmits it. The first repeater will then re-transmit it.

This creates an endless loop of the repeaters repeating the message.


A repeater chain can be made to work on a single radio channel but the repeaters have to be intelligent and be able to at least recognise what they have previously sent so they can ignore it and not transmit the same message a second time. The usual way is for the sensor to insert a message number (or date and time ) into each message.


Is there no way you can run a cable between the two locations ? Get a temporary wayleave to run it if there is other property between the sites.

You might get results with ground transmission using two ground electrodes at each site placed as far apart as possible. A range of over a mile is possible but does require a sensitive amplifier.

Or erect a mast to support the transmitter high enough to give line of sight to the house.

What ever you do you must adopt a system that sends regular " All OK" signals as well as "alarm" signals. If the "All OK" signals stop arriving for more than a few minutes then the alarm must be raised. It is no use having a transmitter that only transmits alarm signals. If the thieves smash the transmitter you will never get the alarm message,

 

[OwainDIYer]

I assume this is a building site - in which case the machinery and stock is going to run into tens of thousands of £s?

I would be looking at IP CCTV cameras with internal software motion detection, recording onto internal memory cards, with a GSM dial-up router, acting on motion detection, sending video to your smartphone. This would give you live video of any alerts, together with audio challenge so you can shout at them over speakers. That will usually put people off. However if it doesn't the live video means you can call plod out immediately as you have confirmation of intruders.

All working off a couple of car batteries that you swap over for recharging.

Yes it will cost a couple of £thousand.