"False" alarms on wireless alarm systems

[Europlex]

Do you know that Radio Alarms can be activated, (or using your terminology, jammed) if the circumstances are correct, by, hoovers, elec. drills, lawn mowers, elec. shavers, hedge trimmers, taxi & emergency service radios, CB radio, fluorescent tubes etc etc, the list goes on & on.

 

[S21]

Our end users know the system is jammed because the siren will activate in those conditions. This prevents burglars trying to bypass the system by jamming them as the alarm goes off anyway.

if you read what I put - no it wont, and your end user will have no idea.

 

[alumni]

Ok so you have the appropriate equipment with the appropriate reporting so can you say out of all the wireless alarms you have fitted how many you have had inteference problems with or 'jamming' issues.

Now answering this you are either going to admit you have knowingly fitted suspect equipment or you are going to admit you rarely have issues.

Which way are you going to go.. I suspect another dodged answer.

As already mentioned, nothing to dodge.
You've turned, yet again, a generic, but pertinent, statement into a specific to try and defend your position.

You only fit wireless, and low end at that. We choose when, where and if we want to fit wireless - that alone helps minimise any potential risks. The readings/reports on install are all checked. Any 'issues' will be logged/reported and acted on accordingly, likewise any future incidents. Like i say, we have options, you don't simply because you persist in trying to convince the world, one yellow box is the answer to all.

 

[Alarm]

One I suspect was due to roofing work accross the street and the roofers drilling - perhaps old worn drills with sparking brushes.

So YOUR saying, a person using a worn drill..................will fool a Yale system. Or the roofers "attitude"?





If it was not so serious I would laugh.

 

[yaleguy3]

Do you know that Radio Alarms can be activated, (or using your terminology, jammed) if the circumstances are correct, by, hoovers, elec. drills, lawn mowers, elec. shavers, hedge trimmers, taxi & emergency service radios, CB radio, fluorescent tubes etc etc, the list goes on & on.

Oh look your matey points it out too...

 

[Europlex]

He, he, look at what I've just seen in another Forum ...................


"Hi all

New here and hello. Hoping for a bit of helpful advice.

First some background, at various points in my life I have worked as an electrician and in IT and data cabling, but never anything concerning alarms. So although I know little about alarms except what I have read on the net and the Gerard Honey book, I am OK with things technical.

Recently moved in to a new house and the wife wanted an alarm. I bought a Yale wireless which was nice and easy to install, but then I found out I could jam the whole system with a car key! So that won't be staying and I want to install a proper wired system.

The texecom range has been recommended to me, so am thinking of installing that. .................................................... "

 

[S21]

Today I will be installing and before I go I will hold my car remote down in an effort to replicate this apparent incident. lol

you may want to get hold of an old school Visonic reciever and see what happens to the activity LED when you press your car alarm button.

or buy something decent and take a background RSSI reading when you press your car alarm button.

you`ll be suprised.




the fact is you don`t understand how this stuff works

 

[bernardgreen]

You are right any reciever will pick up a signal at the right frequency from any transmitter.

A good quality ( as in selective ) receiver will pick up a signal on the receiver's frequency and hardly be affected by signals on other frequencies. A poor receiver will be seriously affected by signals that are not on the receiver's frequency/

That is the whole point of learning things into the system. Every Yale sensor be it a door contact , pir , smoke detector , keyfob or whatever has its own unique ID.

Which has nothing to do with jamming. The ID has no value if the signal carrying it cannot be heard by the receiver.

That was over two years ago and I have not had a single issue with crosstalk , false alarms or alarms that have not activated when expected.

Have you asked if there have been any detected issues or is it that no one has thought it necessary to report issues to you. ?

I am not disputing your facts Bernard only that in the field in a typical domestic or even a less than ideal domestic environment I have not experienced the problems you have indicated.

They are not "my" facts, they are facts of radio transmission systems. If you have no experience any of the problems that beset radio communications then I would suspect you have not followed up many or any of the installations. Or the users have not been aware of the problems being there in thier system. Have you ever disabled the jamming detection circuit to prevent false alarms ? ( as you recently advised as way to reduce false alarms ) If you or the users have dis-abled it then that system could be totally useless as an alarm system if there is any source of radio signals that block ( jam ) the siren's receiver when the intrusion occurs.

 

[yaleguy3]

Today I will be installing and before I go I will hold my car remote down in an effort to replicate this apparent incident. lol

you may want to get hold of an old school Visonic reciever and see what happens to the activity LED when you press your car alarm button.

or buy something decent and take a background RSSI reading when you press your car alarm button.

you`ll be suprised.

the fact is you don`t understand how this stuff works

I understand how the stuff works it's just that after many many installs over a number of years it just hasn't been an issue.

It may be the case that if I site myself within feet of the panel or siren I could replicate this jamming as I already know that in some cases wireless routers can drown the systems if the router is too close to the panel. The solution is easy though just keep them further than a metre apart. The car remote is a LP device and therefore has a limited range by law. It is one thing pressing one directly adjacent to a panel and another being down at street level while the siren is 20ft up in the air.

 

[bernardgreen]

Car fobs and alarms.

I am certain they both operate on the same SRD ( Short Range Device ) frequency, perhaps YaleGuy3 can check that out.

An example of problems with SRD equipment and car keys is here

http://news.bbc.co.uk/1/hi/england/cumbria/8545104.stm

similar incidents have occured all over the UK. Often the effect is limited or short term as the offending SRD is not transmitting continuously and these incidents tend to only get reported when the offending SRD is over power or transmitting for long periods of time. The important part is that proviced the SRD is on frequency and its ERP ( effective radiated power ) is within the limits imposed by the licence ( common to all users ) there is nothing to prevent it being used even though it interferes with other users of the channel.

Hence radio using SRDs on a common licenced frequency should only be used as a last resort in situation where a wired system is impossible and not just difficult to install.

 

[yaleguy3]

In response to your reply Bernard the information you gave from the University was very interesting.

However it made it quite clear that the problem is worse when the receiver is poor quality and picks up a wider spectrum of noise.

Maybe I have not had an issue with these problems because the Yale receivers are well designed?

 

[bernardgreen]

I understand how the stuff works it's just that after many many installs over a number of years it just hasn't been an issue.

Forgive me if I doubt both those statements

The car remote is a LP device and therefore has a limited range by law.

The range cannot be limited by law, only the ERP can be limited. The range is determined by many factors including the sensitivity of the receiver, the propagation path between transmitter(s) and receiver(s)

While these experiments http://naqcc.info/qrpworks.html are very extreme they do show that a very low power transmitter can be received many miles away. I recall that using standard SRD devices in good conditions ( no other transmitters active in the near field area ) data can be passed over a mile.

 

[yaleguy3]

Bernard you are right I am not disputing your information or the information of the universities or the way the whole radio frequency sharing is allocated or handled.
It just has never been an issue to me personally in any significant way.

Surely if the problem was as potentially problematic as suggested I would not even be able to fit the alarms in the first place without the problem manifesting itself .

I have never been in a situation ever where I could not properly commision a system because spurious false alarms were occuring.

 

[yaleguy3]

Bernard we could continue this debate round and round in a circle for a long time as we both actually have valid experiences.
The Yale systems have been around in the current guise for a long enough time for any major issues to present themselves.
As things currently stand it is not a significant problem at all.
Yale sell hundreds of these devices on a weekly basis and have done for years.
Had a problem become a real issue it would be all over the consumer boards by now but it hasn't.

Wireless usage in a typical home environment has not accelerated as expected. Home automation has ended up being an idea that noone really took to so we have the usual scenario of wireless routers - mobile phones - car remotes and doorbells as the usual potential conflicts.

In practice they all live happily together.

 

[S21]

It is one thing pressing one directly adjacent to a panel and another being down at street level while the siren is 20ft up in the air.

fella, dont make the mistake of assuming I need things dumming down to your level.