How Amazing Are Today's Motion Detector Systems?
Today's motion detectors are amazing. In the bad old days, motion sensors would go off with the drop of a hat (literally).
Pets, sunlight and even the wind would set them off. Today, motion sensors are much more intelligent, and use a range of technologies to avoid the dreaded false alarm.
In addition, in the old days, sensors had to be placed where your electrician could connect them to the base station. Today, wireless motion detectors make it possible to install sensors exactly where you want them.
Outdoor & Indoor Motion Detector Systems
Motion detector systems come in two basic forms: outdoor and indoor.
Outdoor motion detectors (otherwise known as driveway motion detector systems) let you know when someone is approaching your home. They are often coupled with a lighting system, which lights the way for guests (and you!) and lets intruders know they are monitored.
Indoor motion sensors can detect an unauthorized presence in your home. This can be when you are away at work, on holidays or asleep at night.
Improvements in Motion Detector Systems
In the bad old days, motion detectors would go off at the slightest drop of a hat (literally).
If a gust of wind came through the ventilation duct and raised some dust, the sensor would assume it was a person. Housebound pets, such as cats, were the cause of numerous false alarms to security companies and the emergency services. High call-out fees to the owner were often the result.
Today's motion sensing systems use two or even three different technologies to make sure false alarms are kept to a bare minimum.
Infra-red motion detector systems
The first technology is infra-red sensing, which looks for the heat emanated by an intruder's body. To guard against changes in heat by acceptable means, such as sunlight or a parked car releasing heat into a garage, these sensors allow for gradual change, but not sudden change in heat (which an intruder would generate).
Ultrasonic & Microwave motion detector systems
The second and third technologies are ultrasonic and microwave technologies. These both work in a similar way. If you've seen a highway patrolman with a radar gun, you'll get the idea:
The sensor continually sends out microwave or ultrasonic rays, which bounce off an object (usually a wall) on the opposite side of the room. The rays return to the sensor, which times the ray's return trip. If a ray takes less time than usual to return to the sensor, it is because something new has entered the room and the ray is bouncing off it.
To guard against pets setting off this type of sensor, two rays are sent out, both of which must be interfered with for the alarm to be triggered. Small cats and dogs (under 40 kilograms / 88 pounds) should not set off both rays, which means no false alarms.
The Wrap
The great thing about today's motion detector equipment is that it uses all these ideas in tandem. It uses infra-red ray to sense heat (intelligently, not allowing sunlight to set it off) and ultrasonic or microwave rays to detect motion (intelligently, not allowing small pets to set it off).
Better still, today's wireless motion detectors allow you to place your sensors exactly where you want them – not where your electrician finds it convenient to install them.