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Security is a increasing source of concern for home owners today. Bad economic times have led to an increased risk of home breakins and theft. Most security installations are done by professional organizations which will charge you a hefty sum and provide you will iron clad security. However what many home owners need is a simple deterrent system, that will stop the street thief from getting in and wiping the house clean. There are an increasing number of security products in the market which you can install yourself, but it is important to understand the advantages of using each because incorrect use could create a false sense of security while actually leaving your home more exposed than protected.


The simplest security system that is both cheap and acts as a deterrent to theft is an alarm. It is usually installed inside the home. There are mainly three kinds of alarms:

  1. The door/window alarm which uses a magnetic reed switch to trigger. The switch is composed of two parts and one part is installed on the door to be protected and the other on the door frame, such that when the door is closed, the two parts are fairly close to each other. When the door is open the two parts move away causing the switch to trigger the alarm. These only protect doors and windows and the alarm will sound only if the door/window is opened. If the intruder does not open the door/window (for example gets in by breaking the window glass without opening the window frame) the alarm will not sound. These are fairly cheap but not very reliable.
  2. The infra-red beam alarm system uses emitted light to detect intrusion. The transmitter emits a beam of light which is focused on the receiver. If the beam is cut off, the alarm will sound. These can be installed on stairways to detect the presence of an intruder. They are reliable but limited by the range of the transmitter, so the transmitter and receiver must be within some minimum distance of each other. Also they must be aligned properly and nothing must obstruct the direct line-of-sight from transmitter to receiver. They can be mounted a little higher than the floor level to prevent accidental triggering by pets.
  3. The PIR alarm uses light received from surrounding bodies to detect intrusion. These are by far most effective in detecting movement in an area within their field of view. They can therefore detect any intrusion in a room or garden. You can also get a version that uses keyfobs to arm and disarm the alarm remotely. Finally PIR alarms are sensitive to infra-red radiation in sunlight and must not be installed pointing toward an object which could potentially reflect light onto it (like the windscreen of a passing car).

Before buying an alarm

Here are some common points to note before you buy an alarm system:

  • All alarms can generate occasional false triggers and so must be designed to switch off automatically after reasonable time. Too many false triggers and your neighbours will complain.
  • If switched off automatically the alarm must have some way of indicating that it was triggered at some point.
  • Alarms must be wall mountable otherwise they may be removed by the burglar.
  • If the alarm is mains powered the mains cable should not be visible otherwise the burglar will simply cut it to silence the alarm. A battery backup is always advised.
  • If the alarm is battery powered, it must make it hard to open the battery cover and pull out the batteries. It must also provide advance indication of weak batteries.
  • The alarm must give sufficient time for you to exit, enter the protected area and disarm it.
  • Loud alarms can damage hearing and must be kept out of reach of children.


CCTV serves a slightly different purpose to alarms. CCTV allows active monitoring of a house and surrounding premises. If recorded, it can also be used as proof against the burglar if he is caught. In a way it is a more passive deterrent than an alarm. There is an abundance of CCTV systems which support different number and types of camera. Choosing the right one for your home is important.

The simple CCTV system is primarily composed of a camera connected to a display, usually a television or security monitor. The problem with this simple system is that the camera must be connected by a sufficiently long wire to the display. The camera must also be connected to some form of power supply or battery. Also someone must monitor the television image continuously to spot an intruder. We will come back to these issues later.

Before buying a CCTV camera

  • Check what type of power supply the camera uses.
  • If the camera is going to be used outdoors it should be weatherproof.
  • Is the camera colour or black and white? Does it have audio support?
  • Can be be used in the dark. Cameras having night vision can be used in the dark.
  • How strong is the housing for the camera? Can it be broken by throwing a stone at it?
  • What is the focusing distance and field of view for the camera?

Now coming back to the problem of wires. It is possible to buy a wireless CCTV camera system that uses a wireless receiver unit which receives the pictures from the camera using radio signals. The receiver can be connected to a display to view the CCTV pictures. The thing to note is that the camera will still need power. If it runs on mains power, it will still need some wires. If it runs on batteries check the battery life is sufficient. Also the most important question to ask is if the wireless link between the camera and the receiver is secure. Because if it is not, anyone with a compatible receiver within range will be able to hook up to your camera and observe your home!

Finally if you do not have someone sitting in front of the TV watching the CCTV image all the time, the system is pretty useless. So the last block in the puzzle is a DVR or digital video recorder. This device can be connected to the camera or the wireless receiver instead of a display and it can record everything the camera sees. DVRs however have limited memory to record video. Some are smart enough to record only when movement is detected. Most DVRs don't have a display, so you will still need a display to watch the recorded footage.

Before buying a DVR

  • Check what kind of recording media the DVR requires. Does it record on hard drive, DVD or SD Card.
  • Check what happens when the recording memory gets full. Most DVR systems will start over, destroying the oldest recorded footage.
  • Does the DVR record date/time information with the footage. This is useful information for unattended systems where recordings will be viewed later.
  • If the DVR records only on detecting motion, check how sensitive it is. Can the sensitivity be controlled? Also how long does it take for the DVR to start recording after detecting motion. It should take a fraction of a second, any longer and the subject will have already moved away from the camera and the recording will be useless.

Instead of buying a camera and DVR separately it may be cheaper to buy a camera with integrated DVR.

Using your computer for CCTV

For basic home use it may be possible to use your computer connected to a suitable camera for CCTV monitoring and recording. If you have broadband internet a wired or wireless IP camera will come handy. Again it is important to ask if the transmission is secure and who else can see the video output from the camera. Most IP cameras are fragile and not suitable for outdoor use. You can also connect a regular CCTV camera to your PC by using a DVR card or a USB DVR.

Any PC based system that features viewing camera output anywhere using the internet must at least be password protected. Besides, the video stream itself must be sent encrypted over the internet otherwise the stream can be tapped into while it is being viewed by you. Remember the Internet is inherently insecure and unless it is absolutely necessary you should not send CCTV pictures of your home over the internet.