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| | Alarm problems.Notice: Poor design or fitting of alarms can cause false alarms or failure to be triggered when they should. The type and positioning of sensors is important, so should be chosen by proper alarm installers. Anyone making, modifying or fitting alarms should be fully aware of the law and technical issues regarding alarms. The author does not encourage dabbling in circuits that you do not understand or the fitting of alarms by people unaware of correct fitting methods. What should I do about it? In any case, but particularly with car alarms, check for: Poor alarm fitting: Check the positions of sensors. Check whether pets in the house could be setting the alarm off. PIR detectors may be triggered by sudden temperature changes, objects blowing in the wind, etc. Direct bright sunlight may also cause problems with sensors. The smart burglar using tactics. Burglars have been known to purposely trigger alarms, then run and hide. If the owner hears the alarm, they will reset it. So, once again, the burglar sets off the alarm and hides. He will play these games until you decide that the alarm is faulty and switch it off or stop using it... jackpot. Always be aware of this trick and keep your eyes open. Children playing games. If there are sensors that may be triggered from outside, then it is possible that children may trigger the alarm with a ball. Maybe innocently, but maybe they like to see you running around looking for the problem. Children will play. If the problem is uncertain and the alarm is wireless, check for: Identical alarms: Does a neighbour have a wireless alarm? Although each alarm has a code, cheap alarms can have as few as 1024 different codes. This may seem plenty, but not on an estate where alarms are all over and close together. Shared use: A good indication could be whether other alarms are being affected. If other alarms are affected, you may be able to find the source - where is the interference centred? The real problem is that there are now so many wireless products used in homes, so pinning down a particular item may be difficult. Even if you do, will the person stop using it when your alarm is on? If you are absolutely certain that your CB equipment is causing it, then check: Antenna position: Wherever possible, your antenna should be mounted as high as possible and as far as possible from any equipment that may be affected. Coax. The use of old or cheap coax may cause more signal to be radiated by the coax, rather than the antenna. Antenna tuning: Poor tuning of the antenna can cause the coax to radiate signal, which will be lower to the ground and closer to other equipment. It is in your favour to make sure that as much of your signal as possible is sent out at the antenna. Do not leave your SWR meter in line: As the SWR meter can cause losses and produce harmonics, it should only be connected while testing the antenna. Modifications: If your radio has been modified, particularly for extra channels, have it checked out to see if it is the problem. An unmodified, legal UK CB radio should not give out harmonics at a high enough level to cause problems. |
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