Long Range Alert System

[ashscott]

Hi everyone, I'm new here but am wanting to know people's advice on the following:
I'm creating a system that warns me of a disruption (accelerometer gets activated) but I need it to send a message to a central receiver 50kms+ away.

I considered using a cellphone but then I have the hassle of ensuring its charged, getting a sim card etc.

What is the simplest, most cost effective way to achieve this with minimal power consumption? We're talking 6 volts max......

 

[CocaCola]

I doubt you will find another solution that is as cost effective and reliable as a GSM (cellular) module....

Yes, you will need a sim card and cellular service, but it will work reliably in most cases when other solutions likely won't...

 

[ashscott]

Hmmm, I bet GSM is reliable, but the hassles of getting a sim card for each module is a pain. Do you know if there is any way to get any kind of cellular module onto a network without a sim?

Also, a long time ago, I saw long range radio data modems in New Zealand - they could send and receive data (albeit very slowly) from really remote locations - what kind of gear would have been running them and would it fit the bill for the application I am talking about?

Thanks for your fast response CocaCola

 

[ashscott]

As an alternative route, could anyone point me in the direction of a super cheap GSM module?

 

[davenn]

any form of radio transmission over ~ 50km, other than a mobile phone, is going to require significant power and antenna systems. You would have to go to your local licencing authority, eg. -- FCC in the USA, OFCOM in the UK, ACMA in Australia
to get and pay for a frequency allocation, a transmtting licence for eact transmitter etc etc. Its gonna get seriously expensive for you.

mobile phone -- GSM-- modules are definately the way to go --
what sort of sites are these things being located at ? do they have power sources for contineous powering of the GSM and other electronics ?
If not then you may have to consider solar panel and battery

cheap GSM modules ? have you looked on eBay ?? probably a wealth of them there coming out of china

cheers
Dave

 

[CocaCola]

but the hassles of getting a sim card for each module is a pain.

A LOT less of a pain than getting a complex radio system up and running... In the US I can go to just about any store and get a pre-paid SIM card (or phone with a SIM card) for hardy anything...

As Dave said hit up Ebay, GSM modules all over the place cheap out of Asia... As Dave also eluded to, to get the distance you want you will either need a high powered device with a decent antenna or a lower power radio and some really tight directional antennas perfectly aimed at each other...

 

[ashscott]

Ok, so it looks like GSM is the way to go. Let me do some research on modules and I'll come back at ya'll with some questions once I understand a little better.

Am really impressed with this forum - your experience and expertise shines through not to mention speedy responses.

 

[ashscott]

I like the look of this because it is python based: http://www.ebay.com/itm/Telit-GM862-GPS-GSM-cell-module-Quad-band-Python-embedded-TCP-IP-/290820460095?pt=LH_DefaultDomain_0&hash=item43b6400e3f

However, it would seem a little complex for a unit that simple needs to call one number whenever it is disturbed.

Also, I am currently based in India and will be testing it here - are there any protocols that may change between the US and India (in terms of GSM networks) that could cause such a unit to not function here?

Ash

 

[ashscott]

There is also this: http://probots.co.in/index.php?main_page=product_info&products_id=284

But it looks less customizable than the previous solution

 

[davenn]

There is also this: http://probots.co.in/index.php?main_page=product_info&products_id=284

But it looks less customizable than the previous solution

that link didnt work

I would assume the GSM system to be standard worldwide, but finding an expert in that field would confirm if there are any country to country variations

Dave

 

[ashscott]

OK, in case people are interested, here is a guy who did a similar thing for a project: http://www.youtube.com/watch?v=az2v1QgLZrY&feature=plcp

Seems to have worked it out well.

Being a bit of a novice, can anyone tell me if GSM modules etc come with basic wiring instructions?