A PICAXE to detect and prevent theft

[David HK]

Hello,

I last posted on this forum in April 2011 with an enquiry about a Picaxe controlling a garden water sprinkler. Owing to a fall from a step ladder whilst folding double bed size sheets, I have been out of action for a while. Therefore, before I continue with this enquiry may I offer thanks to those who took the time to sit down and write suggestions. I did eventually solve the sprinkler problem by acquiring a new diaphragm which returned the original machine to normal working order.

My latest quest for advice follows this story. Near to my home is a man made water channel and along each side are maintenance roads and planter areas. Every 50 metres or so are stainless steel cabinets for supplying potable water via a hose pipe to the plants when required. The cabinets are about 150 x 150 x 1,000 mm and one face is equipped with a door which provides access to the tap unit. The door also contains a 50mm hole so that the hose can be coupled to the tap and the door locked while water is flowing.

Each watering line consists of about 25 cabinets and the doors mentioned above are locked with a brass padlock.

Of late the local thieves have been smashing off the locks and stealing the brass fittings – tap, non return valve and so on. The local fuzz are on to case but they are pressed for man-power and the prospect of setting up overnight surveillance in 33C temperatures with 78% humidity and mosquitoes (I’m in Hong Kong) is not appealing.

It struck me that a PICAXE that could transmit a cabinet number which could be the answer to surveillance. If the electronics were placed on a suitable tray and the door operated a power ON when open and power OFF when closed then an identifier signal could be transmitted the moment the door opened. The small problem would be the aerial. The area in question is dead flat for considerable distances and nearby is a Government water pumping station where a receiver and ‘on duty’ surveillance fellow could rest in reasonable comfort.

I have done a search on this subject but have not had much luck in finding what I want in the forum.

Can forumites offer me advice and ideas please.

David

 

[techElder]

David, my advice is to purchase a commercial alarm system and have it installed and monitored professionally.

 

[rs2845]

Just to add my comments. I do a lot of stuff with alarm systems and I would also recommend an intruder alarm.

There is a system in the UK called 'SmokeCloak' (search on YouTube).

It is connected to the alarm system and in the event of a break-in the alarm would activate and then the smokecloak unit would fill the affected area with thick white smoke making it impossible for the intruders to continue.

I don't know if this would be suitable for outdoors or for your application, but it's just a thought.

 

[bluejets]

Alarm systems require power of some kind. Running power to each unit would appear costly.
Therefore battery supply. Batteries require charging, so need power. Too costly to run power so use solar panel.
Solar panel the thief will take so battery goes flat.
Battery goes flat, alarm doesn't work and thief takes brass again.
All a bit of catch 22 situation.

 

[srnet]

If there is enough RF leakage around the thief when the door is opened, then the PCBs described here;

http://www.picaxeforum.co.uk/showthread.php?21675-ImprovedPICAXE-GPS-Locator-with-remote-Telemetry-reception

Would work. No real need to power the unit down either, as in sleep mode, waiting for a door switch to be activated for instance, current consumption is around 20uA. So a small 3V lithium camera battery would last several years.

The receiver shown, (groundstation) would just sit there waiting for a packet, the software to display which transmitter is alarming would be easy. It consumes around 20ma when listening for a packet, so a big battery or mains power required.

Those RFM22 modules are more powerful than most, 100mW, but whether there is enough leakage when the door is opened to allow for reliable reception, who can say. But then at the receiving end you have the option of adding a readily available high gain antenna or UHF pre amp to improve the range.

 

[Dippy]

I agree that power isn't a problem. It just requires good design, good code and some imagination.
No-one has discussed the aspect concerning a legitimate person opening the door.

A delay is required for a pukka bloke opening the door and switching the alarm off.
(Unless he/she pokes something R/C switcher-offer through hose hole).

What would you use for alarm?
Tricky.
Even if you had a reliable RF link how long would it be before site was reached by PC Plod?
Ten or twenty minutes? Plenty of time for Crim to smash off fittings.
Nice bright strobe and >100dB siren in the face might make them run off.
Any remote/in-the-field alarms are tricky.

I'm sure this will attract many suggestions including Flashbangs, so good luck

 

[techElder]

I've got an even better idea than my first one.

Change to all plastic fittings.

This idea may even be cheaper in the long run.

 

[bluejets]

No-one has discussed the aspect concerning a legitimate person opening the door.

Easy.....key switch.

The biggest problem is no one gives 2 hoots about alarms except "when are they going to shut that **** thing off" and that's a fact.

 

[Markbishop16]

Texecom Ricochet wireless alarm system if you can get it in HK.http://www.texe.com/ricochet/
Its the only Mesh Networking system I know of so range is not an issue, you can put 30 devices per receiver. Fit a door contact transmitter to each door then signal back to the control room. Switch the system on when you want from the central keypad. Each device will tell you on the LCD keypad where the activation is. The batteries will last for 3 years.

Other wise you may be able to get a Visonic ( Tyco) product which will be cheaper http://www.visonic.com/innovation-technologies/technology-leadership. This works well again a door contact on each housing and control panel in control room.

None of this is as fun as making Picaxe stuff, but, sometimes something off the shelf will save hours of teeth grinding. Also both units can ring out so it you do not have a guard on site it can ring the short straw and tell them where to go and shoot.

Also on a different note do the HK Police still carry Greener GP shotguns?

 

[David HK]

Forumites,

Thank you for the interesting notes.

Firstly, commercial kit, permanent installation, far too costly.

Slave units – no bells, whistles, flashes, smoke, LED’s – totally silent operation. Only has to trigger when power comes on – open door – and transmit unique ID which is the cabinet number. Does not need to receive from master. Battery operation is perfect because it may only be deployed for a short period – a few days, perhaps a week or so.

Master – just needs to receive and display ID number of activated slave.

Plod response can be on foot – minutes away, or faster on silent electric bicycle. Road in excellent condition and has public lighting with little or no traffic at night. Deployment of SWAT team with night observation devices is overkill.

Target – Chinese villager(s), very clever, know the ground like the back of their hand. Not electronically clever however.

TX/RX range max is about 0.67K or 0.42 miles. Open drainage channel with small bushes low height flora each side.

Hong Kong Police Greener guns, I trained on this weapon when I joined in 1969. Nice bit of heavy kit (probably as heavy as a .303). Used brass cartridges loaded with .303 lead balls. The best ammo was used by the BSAP which was loaded with rock salt. The weapon was phased out in the 1970’s and replaced with the Remingtom pump action shotgun which fires a variety of ammunition. Still in use today with riot companies.

Deployment of the kit would be known by those involved. The cabinets are never used for providing flora watering because the locals steal the kit so fast that the supply valve is permanently off. On some other adjacent supply pipes the smarter locals dig down and intercept the supply pipe to provide home water for washing and gardening use. They ensure the supply ‘stays on.’

David HK

 

[David HK]

I suppose one could go in a different direction and glue a plastic disc over the water pipe hole in the door of the cabinet. Thereafter a bamboo snake or a small cobra, or a banded krait locked in the cabinet might be effective. After the locals had smashed the lock off the door the snake should be wide awake and ready to go! There are plenty of these snakes around at the moment especially kraits.

David HK

 

[Dippy]

You say permanent installation is far too costly, does that also mean that screwed-on sensors and keyswitches are also off the menu?
Are you aiming at a cheap little box-of-tricks that can be stuck inside with blu-tack? (not literally).
Are the taps meant only to be operated by 'officials' or also by planters and their chums?

Will there be valid users overnight?
Tell us what is ideal for you.

 

[David HK]

Dippy,

Answers in sequence are:-

Yes, basically the concept for the slave is a simple PCB which can be easily replicated and just held inside the cabinet on a split bamboo frame – easy to insert and easy to remove. If lost, damaged or destroyed it can replaced if required. It is not a long term project and is only aimed at making a (anticipated) one off arrest for theft.

Yes.

The cabinets containing the water taps are permanent items but rarely used for flora watering because the plants are hardy enough to withstand local weather year round. The local contractor working for the Government Department concerned has access to the cabinet keys and it matters not if they know the cabinets contain an electronic alarm.

There are no overnight users. In fact daytime use is a rare event. I have only observed flora watering twice in about five years.

David HK

 

[Dippy]

We need a Design Requirement document

Summary.
A stand-alone low-cost device.
Battery powered.
Door open / tamper detector.
Radio linked.
Receiving Unit somewhere.
Can be set to ignore valid users somehow,
Notifies someone somehow.

Do you think it should the board should be in a box?
How do you envisage it will actually detect the door being opened?
How will it (or the people or the police) differentiate between naughty boy and valid user?
Will it need to transmit RF through the steel body and/or rely on some RF escaping out of open door?
Is the door big enough such that it can go on inner face? Bringing the Tx outside could help.

Finally, what is your own skill level wrt construction, electronics and coding?

 

[manuka]

I know HK culture to some degree, so please let us also know what rules & regulations apply! There no doubt WILL be more than a few...

 

[JimPerry]

Better steel locks?

 

[techElder]

Uh, I know how this ends ...

 

[David HK]

Texasclodhopper.

You are right. The questions from Manuka and Dippy are designed to drive people away. "We need a Design Requirement document " - I am 65 years old and have no idea what format this should take. Is there a specimen available for reference. For goodness sake be nice to people. The best recent request I have seen was from the Captain of a ship who wanted to monitor the temperature of propeller shaft bearings - a fabulous concept which could be done with PICAXE technology. Yes I can design PCB's. write moderately simple software, and specialise in renewable energy technology.

I give up using simple English to explain a simple requirement and will never post on this forum again. I never had the good luck to attend University and have to teach myself electronics and programming as I go along. I feel as of I have been publicly pilloried.

David HK

 

[srnet]

Remember Bonds Lotus with its 'Burglar Protected' stickers ?

 

[David HK]

srnet,

No I do not remember Bonds Lotus, I have not watched television since 2000, I have not purchased a newspaper since 2000, I have not listened to English language radio since 1st April 2004. The last cinema film I saw was Jurassic Park and that frightened me to death.

David HK

 

[Buzby]

... The questions from Manuka and Dippy are designed to drive people away.

Dippy put a little smile on the end of "We need a Design Requirement document ". It was humour.

Manuka is checking that you will not fall foul of the authorities if some thief poisons himself when he eats your lithium battery.

Don't take it too hard, it was you who suggested a snake !.

 

[David HK]

What lithium batteries? I have never mentioned them. My eyesight used to be good, now I have to wear spectacles, and to read small print I carry a 10 cm diameter magnifying glass in my day bag. I know the authorities here and can easily check up on Laws of Hong Kong which are available on the Internet in bilingual form.

The snake idea was meant to be a pleasant interlude because some long serving forumites like to play along an interesting saga.
David HK

 

[Dippy]

My comment about a Design Requirement Document was a joke - hence the smiley.

And when you mentioned snakes that frightened me, but I still managed to type (a joke).

"..designed to drive people away"
- not at all. I'm sorry you should feel that way.

You put the first part clearly, but we need to flesh things out.
I asked your level to help others to put any design plans in a clear way.
And I was trying to prompt you to consider some possible ideas.
Once that has been nailed then people can suggest things at an affordable price.

And , don't worry about Manuka, Stan often asks for people's inside-leg measurement when replying - that's his way (Smiley)

 

[David HK]

I am old fashioned. I do not play around with these Smiley things. I can see the yellow disc/circle and know that other small black circles and lines are inside them. But I do not recognise them easily with my level of eyesight. I would never dream of sending one to another forum member as part of a text message. I deal in straight and simple English text/language which I can just manage to read.

Why is it that extraordinary mortals cannot appreciate this?

David HK

 

[JimPerry]

Hi David

I'm in my 60's as well, and used to design security systems 40-years ago, so my "Steel Locks" post was not facile!

Might have the germ of the solution for you and the rest of the Picaxe Supporters Club <<< SMILEY FACE

Steel locked enclosed boxes tend to make a lot of "clang" so a cheap-as-chips sound activated light (only 99p in UK - made in China) would make a good stating point. Use this to connect to a Picaxe controlled 433MHz transmiter and then a base-station.

The sound box is amall and holds 3 AAA cells - minute standby current - very sensitive to "clangs". normally lights up 3 white LEDs for about 15 seconds.

Would be trivial to wire into a Picaxe/TX circuit instead of LEDs.

Do you have a sketch or photo of the box closed and open? Would help in figuring out where/how to mount it all - plus the question of it being a Faraday shield could be thought through.

Does it need to be silent (catch them in the act)? or just a deterent (flashing light and visual sign of security)?

What is the budget (cheap enough boxes could be everywhere, only a few need the expensive electronics)?

Cheers

JimPerry

 

[geoff07]

I would be tempted to get a gsm to send a text message to the police monitoring the site when interfered with. And the sensor could be a picaxe with a contact or a tilt or even a light sensor. Others can advise on linking to the gsm to trigger the text but HK must be full of people who can do that. You would only need to fit a few, on the most tempting sites. Power could be a small dry battery with enough juice for a few days.

 

[Buzby]

... Change to all plastic fittings ...

Excellent idea !

Now another non-PICAXE solution.

David said,

The cabinets are never used for providing flora watering because the locals steal the kit so fast that the supply valve is permanently off.

and,

I have only observed flora watering twice in about five years.

From the words 'never' and 'twice' we can deduce that the theft rate exceeds the legitimate usage rate.

My suggestion is, turn the supply valve off permanently, and use a road tanker full of water when the weather gets too hot for the plants.
This also thwarts the burrowers who are after un-metered water.

The annual savings in the cost of replacement fittings would go a long way to paying for a bowser.

[* No smilies were harmed in the production of this posting. ]

 

[Buzby]

... get a gsm to send a text message ... small dry battery with enough juice for a few days.

The GSM uses a lot of power, but it only needs to be powered up when a break-in occurs, so set of AAs would last until the next break-in, even if it's months away.

 

[manuka]

Recent HK metal theft news. The soaring cost of metals has made this a global problem,with copper cables & piping especially vulnerable. Google has numerous cases - power lines being ripped down, earthing links removed & even brass cemetery plaques uplifted etc.

Light fingered rascals may be misguided, but (aside from those -ahem-that TRY to steal live wires...) many are not stupid, & even the best security may be defeated. It hence also strikes me that a change to plastic plumbing fittings would overcome the HK problem. Stan.

 

[techElder]

That's why I said the same thing early on.

It struck me that the OP had a system with little use and was trying to "protect" something just for the sake of "protecting" it. Perhaps because that is his duty or charge. However, after a long list of technical suggestions and queries, the OP is upset with the need for drilling down into the technical requirements of the project. Perhaps because of a misguided sense of how simple the solution should be when "computers" can do anything simple well.

So now the discussion devolves full circle.

... It hence also strikes me that a change to plastic plumbing fittings would overcome the HK problem. Stan.

 

[AllyCat]

Slave units – no bells, whistles, flashes, smoke, LED’s – totally silent operation. Only has to trigger when power comes on – open door – and transmit unique ID which is the cabinet number. Does not need to receive from master. Battery operation is perfect because it may only be deployed for a short period – a few days, perhaps a week or so.

Master – just needs to receive and display ID number of activated slave.

TX/RX range max is about 0.67K or 0.42 miles.

Hi David,

In My Opinion your original request may well be "best" (for your application) but the radio transmitter and antenna are probably the greatest cost and challenge. That is a "significant" range for a cheap transmitter/receiver. It depends whether the system needs to be "legal" and what are the wireless regulations in HK? Do you have any experience and specific plans for the radio link you want to use? (if not, then one of the "alternative" solutions above may indeed be better).

Perhaps one of the "model control" or CB frequencies (27/40MHz) would be suitable (but frowned upon by modellers here in the West) since a "piece of wire" may suffice as the antenna. As others have said above, the metal enclosure, even with the door open, is likely to be a problem. For a "transmission protcol" probably little more than an "automated morse" signal/receiver is required to report the ID of each location.

There are various options for triggering the alarm, magnetic reed "relays" are common in alarm systems because of the very low occurrence of false alarms (if installed correctly), but an electret microphone (maybe with a one-transistor amplifier) or even a "flying" plug pulled out of a socket by its cable when the door opens might be sufficient. Note there is a thread/blog on the forum which mentions a very cheap alarm system (from a Dollar/Pound Store) which uses a "naked" reed relay (no glass capsule), very cheap but virtually impossible to "cannibalise" for any further use.

Cheers, Alan.

 

[Goeytex]

An RF solution would be good, except for locating the antenna where it is effective and tamper proof. I think that is the main challenge with RF.

Any of the Dorji DRF4432D20 Transceivers (or equivalent) should be adequate for 700 meters assuming Line Of Sight antenna location.

I am not sure what frequencies are allowed in Hong Kong but 433MHz is used in China.