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Alarm Systems using Internet and mobile phones

This page deals with Internet-connected detecting devices of different kinds. One interesting example of this technology is the proliferation of webcameras, whose pictures are generally available on the Internet. Cities, such as for instance Seattle in the USA, can show maps where web camera positions are indicated. The visitor can click on one of these positions, and get a direct view of what the camera sees.

As shown in view A in the illustration at right, Internet-connected devices can be directly addressable from the Internet (the IP-addresses used in the illustration are just examples). But this is rarely done, both for administrative reasons and to save IP-addresses. The most common solutions are instead to configure the detecting devices into LANs (as in view B) or into WLANs (wireless LANs, as in view C).

Contact with these devices are not limited to the Internet, however. The use of various wireless technologies is mushrooming, and two-way contact with these devices, using for instance cellular phones, is quite possible. The usual way to do this is by way of a central control and communications unit, as shown below, which can handle several detecting devices of different kinds, configured in a local network.

Different ways of connecting the control unit to the outside world

As shown, the central unit controls, on the one hand, all the detecting devices, and on the other can communicate with a local computer, with Internet, over a phone modem or by acting as a cellular phone.

Three different ways to connect IP-addressable detecting devices to the Internet

The philosophical aspect

Ye olde communication philosopher

As premiums for property insurance keep increasing, the interest in burglar alarms and detection devices for prevention of damage is also increasing. It is rather peculiar to note that these kinds of devices are not as obvious features of homes and business premisses as are telephones and electricity. The apparent reason is that people often regard them as unnecessary expenses, and donīt do enough as real protection against theft and damage.

But times are changing. As insurance premiums go up, these kinds of devices are becoming cheaper. And we can actually do something about their efficiency, if we make proper use of todayīs communications possibilities. Consider these facts:

  1. Alarms are often activated unnecessarily, causing irritations with those who have to deal with them.

  2. Audible alarms are often ignored. And professional trespassers know how to shut them off.

  3. Alarms connected to police cannot always be acted upon quickly enough to be of any use.

  4. Alarms connected to manned security systems are expensive. They are not affordable to most people or even to most small companies.
What we would like are:
  1. Alarms that quickly alert persons near the premises, such all-night mall security, neighborhood watch or police patrols.

  2. Ubiquitous camera systems that allow such personnel to view the premises so they can decide what needs to be done.

  3. Cameras that could film the perpetrators for later identification.
Regarding the last point, it should be noted that if one needs photos to show in a criminal court, they have to contain analog information, since the courts in most countries do not regard digital pictures as evidence. The reason is, of course, that digital pictures can be manipulated in computers; it would be too easy to falsify evidence this way.

The biggest need is, thus, to quickly convey accurate and complete information about whatīs happening on vacated premises, to those who can as soon as possible do something about it, and not to bother persons who canīt. And to do this at an affordable price, so that all areas and objects that might need some kind of protection also gets it. The smartest way to accomplish this is by way of:

  • Using latest technology for detction devices.
  • Using Internet and mobile phones to reach people with alert messages.
In case of long-distance communication, this is best done by using the Internet and the GSM network.
Types of detectors

A webcamera

One can divide detector types in several ways. One way is to differ between those detectors that report continuosly, such as web cameras and "hearthbeat detectors", and those detectors that are set to monitor certain activities, and only send reports when such an activity occur. Another way is to differ between active detectors (which require a constant power supply) and passive (which do not).

Communication interfaces:

  • Phone modem
  • Internet
  • Cellular phone (GSM, GPRS, 3G)
  • Local computer
  • LAN
  • WLAN
Positioning technology used: GPS and GMS.

Types of detectors

The detectors themselves are the usual kinds, that have been around for a while, such as:

  • Motion detector for detecting moving objects.
  • Infra-red detector for detecting sources of heat.
  • Node with magnetic contacts for protection of doors and windows against forced entry.
  • Smoke detector for fire alert.
  • Flooding detector.
  • Temperature node for detecting if temperatures get too high or too low.
  • Control node which can monitor 230-volt equipment.
  • Level indicator.
The Technology

We at Johnson Consulting intend to present technical details of installation and function of this equipment in this space, as time permits.


Last Updated: 2007-01-02
Author: Ove Johnsson