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home security system design

Former Member

I promise u I am not in the electronic security business.  I'm just a tech enthusiast & do-it-yourselfer.  As such, I had put together my own home security system yrs ago.  It's time to upgrade.  Mine has a telephone dialer/msg player that dials up several phone no.s and plays my pre-recorded msg to each, when the alarm is triggered.  I do not use a private monitoring co.  It calls me & police directly.

Seems 2 me that a big flaw in a home security system is dialing out over a land line whose wire can easily be cut, where it enters the house.

Where can I obtain a cellular base station unit (or how can I adapt a cell phone) to work with a recorded-msg-player and alarm center triggering  (my alarm center will trigger add on components by current signal or by relay contact closure).

Of course, why does anyone build it himself & skip the monitoring co., but 2 save $.  So, I don't want 2 pay 4 a cell phone no & contract just 4 a cell phone that will sit unused most (hopefully all) of the time.  I'd like 2 adapt one of those pay-only-for-the-calls-u-make phones if possible (? Jitterbug or whatnot).  I know that phones fron defunct contracts will still work to call 9-1-1, but I'd like it 2 call me also, so I can go 2 web site 4 my web cam.

FINALLY - THE QUESTION - do u know of such device avail 4 sale anywhere, OR do u want 2 design such a product to market 2 the various do-it-yourself home security alarm mfgrs (GE, X-10 Powerhouse, etc)

  • 0

    Hi Pete,

     

    I maybe move this to the wireless group where you could get more (and probably better) answers than mine.

     

    There are plenty of gsm/gprs/3g modules available. The best one for you would depend on your own expertise and how much you are willing to spend. You should be able to buy industrial SIM cards quite easily, which should save you buying a phone. You'd probably find it easier to send text messages rather than voicemails.

     

    Have a look at some of these modules to see what could be available http://uk.farnell.com/enfora, http://uk.farnell.com/tellit&gprs, and http://uk.farnell.com/3rdplatform

     

    These links are for the UK, if you are anywhere else let me know

  • 0 in reply to awinning

    i"m in USA

    thanks 4 your help

    not sure what u mean by modules.  will ck out the sites

  • 0

    There are commercially available systems in the UK. Unfortunately, as like us all, we want something for nothing. Monitored line connection attract an annual premium of course, as with GSM connections, but they do tend to be a fixed price. Beause the main stream panels tend to be sponsored by what's in place already, it is unlikely that you will ever get a company to develop such an item, as it will not be commercially viable for them. Mobile providers are only interested in the networking and selling space and offering packages, and there is no formal link between the two. With the advent of android phones - thinking logically, an open email connection to a windows based programme could be triggered via an external source. Food for thought

  • 0

    If you've already got a working autodialer, why not try this:

     

    Build a reasonably long ranged radio link to activate it (UK allows 500mW at 458MHz, so a few miles range is quite possible). Then re-site the autodialer in the home of a friend/family member/co-worker, connected to their landline. Then offer them the same service (siting their alarm dialer on your landline).

      No GSM costs, and a burgar cutting your landline doesn't disable your alarm

  • 0

    There are various ways to get "free" M2M communications over cellular. The tricky part is getting the cellular plan for a "calls only" service. I am not aware (in the USA) of any plan like you describe. All the pay-as-you-go plans expire (and release the phone number for reuse) if you don't add dollars/minutes every so often - usually every 30 to 90 days.

     

    From a hardware perspective, the simple hack way to do it is simply to drive the keyboard lines of a phone directly from your micro. I've done this in the past. Due to the way they're implemented, it is easiest to use relays for this task. Your life will be simplified if you can program your numbers into the phone's speed-dial memories so that you only need to "press" the 2 button for 2 seconds to dial the first number, and then END to end the call.

     

    SOME phones have a reasonably-documented serial protocol available on an external connector. This is annoying and hit-or-miss though.

     

    You can also buy a GSM module that can be controlled with AT commands - that way you only need a UART to talk to the module, and an audio path. This will not be as cheap as a $30 (or less) throwaway phone, however.

     

    One thing you might not have considered is to use an Internet-based service to do the dialing - use your broadband connection as the backup to the phone line. There's a long discussion we could have about the infrastructure options here. Personally I don't usually pick up voice calls of any sort - I use my phone as an email/web/SMS device - and I don't have a home phone line at all. So my preference for M2M notifications like you describe is email or SMS anyway.

     

    Oh, one other final point: Without going into details, I can assure you with absolute definitive finality (insert as many other strengthening words as you like here) that no alarm manufacturing company will buy your design. Their existing designs are already capable of working this way, but for business reasons are not implemented like this.