Documentation of Security Systems

The increasing sophistication of domestic, industrial and vehicle security systems has created a need for documentation at both user level and technical level. Systems are available that minimise false alarms through verification, but documentation is required to ensure that they are operated correctly.

I am a freelance technical author with a chemical engineering background and have worked with safety-critical systems, monitoring and control of gas and electricity supplies, instrumentation and motor vehicles. I would be interested in applying my skills to documentation projects within the security industry.

Domestic Security

Increasing levels of domestic burglaries have resulted in the widespread use of audible alarms. While these may be sufficient to deter a small-time opportunist thief, they will not deter a determined criminal, even if the system is connected via the telephone to a monitoring centre. The high level of false alarms caused by these systems causes a burden on the police, who will be less likely to respond if they know that the same system has caused false alarms in the past. Consequently, some genuine alarms may not be dealt with.

In response to a need for verification, alarm systems have been developed which use audio-visual techniques, to enable operators at a remote control centre to monitor the activities within a house, to determine whether or not a police response is required. Sensitive microphones are installed, which can detect noises from any part of the house, and the sounds are analysed to distinguish between normal domestic noise and the activities of a burgular. A system like this might operate in the following modes:

The occupant can contact the remote control centre in all three states by pressing the Request Assistance Button. Each occupant of the house can be given a portable button, and there is also a button on the unit itself. The RAB button may be used under situations of duress such as personal attack, or it may be used in medical emergencies, in which case a doctor will give audible instructions to the occupants telling them what they should do while an ambulance is on the way.

If required, the system can be supplemented with video cameras, to identify suspected intruders within the house.

These type of systems are much more effective than audible alarm systems, because the police are only called when the presence of an intruder has been verified. The police will always respond to a verified alarm situation.

To be effective, these systems have to distinguish between intruder noises and other types of noise with reasonable accuracy. Obviously it's no good if the system connects to the remote control centre every time a train goes past. The effect would be simply to transfer the administrative bottleneck from the police to the control centre, where operators become preoccupied with irrelevant data when something more significant might be happening elsewhere. However, with current technology this should not be too much of a problem. I have seen this type of system demonstrated, so that it creates an alarm response when someone pushes against the glass panel of a patio door, but it doesn't respond to someone knocking on the door.

Commercial Security

The type of equipment that is suitable for commercial sites varies greatly from one site to another, depending on the number of buildings and the siting of equipment in open spaces.

The audio-visual techniques described above, for domestic premises, would be suitable for office buildings of any size with the installation of additional microphones and video cameras. However, the use of microphones would be unsuitable in high noise situations where there is operating machinery. In this case, other devices would have to be used to trigger a connection to the remote monitoring station, such as infra-red sensors, light beams and pressure pads. Verification can be achieved by observing the sequence of triggers as the intruder moves from one sensor to another, and by the use of video cameras.

Special precautions have to be taken at sites with large quantities of flammable material, such as oil refineries, to prevent ingnition of flammable atmospheres. On these sites, all electrical equipment has to be certified as safe for its intended use. Safety measures may include the sealing of equipment, anti-static certification, or continuous purging of equipment with clean air under positive pressure, taken from a source that is remote from any flammable materials. The installation of security equipment has to follow the same safety rules as all the other site instrumentation.

Motor Vehicles

Motor vehicle alarms are subject to the same problems as domestic alarms. Nobody takes much notice of car alarms going off, and the police are unlikely to respond unless someone calls and says they have actually seen something suspicious. Immobilisers are more effective because they prevent the vehicle from being driven away, but can be circumvented if a thief can discover the security code.

Some vehicles are fitted with tracker systems which connect to a remote monitoring station and identify the position of the vehicle after it has been stolen, so that it can be recovered. These are expensive and are only fitted to high-value vehicles, but the technology is becoming cheaper.

In the case of large commercial vehicles which carry expensive loads that might be attractive to thieves, it has long been the practice of haulage companies to keep in contact with their drivers using radios and hands-free mobile phones. The audio-visual techniques that are available for domestic premises can, in principle, be used in commercial vehicles so that a link to a control centre is established as soon as there are sounds that are incompatible with the driver's normal use of the vehicle. Of course, the system has to be tuned to ignore engine and road noise.


I would be interested in documentation projects on any type of security system, either at user level or technical level. Obviously the technical level documents are a matter of security themselves, as they cannot be allowed to fall into the wrong hands, but there must be a lot of less sensitive documentation that needs to be done at the user level, and for use by salesmen who wish to demonstrate security products to customers. Please get in touch with me if you have any enquiries.

Copyright 1999

Mike Gascoigne, Write_on
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See also the Security Net.