The terms “Tip” and “Ring” go back to the very early days of the telephone industry when phone calls were made with the assistance of “central” – the friendly telephone operator who worked in the nearby central office (could that be the early equivalent to today’s CO?).

Seated at her switchboard, the operator was notified by a light and sound indicator when you sent a signal from your telephone. In order to speak with you, she pulled a cord from amongst an array at her desk and plugged one end into the receptacle that was wired to your location. This completed the connection from your premise to the CO. Once you advised her as to which other party you were trying to reach, she pulled another similar cord from her supply and plugged it into the appropriate spot for that party. The connection was now complete.

So what was on the end of the cords she was plugging in? Each had a metal jack that looked something like this:

That’s right! “Tip” referred to the tip of the jack, and “Ring” referred to the metal ring nearby and separated from the tip by an insulator. In some cases when the same jack was used for applications other than a telephone connection, a third conductor was wired to the “Sleeve” position which was once again separated from the “Ring” by another insulator.

Furthermore, in the telephone world, “Tip” was connected to the GREEN wire in the cord, while “Ring” was connected to the RED! Does that sound familiar?

So now you know! Have a bit of fun with your colleagues around the water cooler or on your next coffee break. You will be surprised how few are as “educated” as you now are.

Pet immune detectors use precise optics and specialized signal processing to distinguish between signals caused by humans and those caused by pets. This allows them to ignore signals caused by one or two pets up to approximately 45 kg or signals caused by numerous rodents.

As a car pulls into the parking lot at night, the headlights sweep across the detector’s mounting location. Because the PIR sensors are sensitive to slight temperature changes, they detect the headlights at both short and long range. Of course, the white light sensor detects the headlights too.

The key to this scenario is the synchronization of the data from the PIR sensors and the white light sensor. The heat and light change in tandem each time the headlights sweep across the detector. The microprocessor algorithm is aware of this synchronization and determines that this is not a valid alarm condition. The security system does not go into alarm.

Aware of the white light sensor and its role in preventing false alarms, a burglar tries to trick the detector with a flashlight.

Because of the location of the burglar, he appears only on the long-range PIR sensor, not the short-range. And since the disturbance is detected at long range, the sensitivity of the microwave sensor is increased and its alarm threshold lowered. Most importantly, the microprocessor algorithm is aware that the data from the PIR sensor, the white light sensor and the microwave sensor is not synchronized and determines that this is a valid alarm condition.

When a mouse is just 4.5 m from the detector, only the short-range PIR sensor reacts. A human intruder that close to the detector would reflect a large area to the microwave sensor, so when only the short-range PIR detects a signal, the microprocessor raises the microwave sensor’s threshold. The distance data provided by the two PIR sensors allows the microprocessor to vary the microwave sensor’s threshold. And because the mouse reflects a small area to the microwave sensor, the newly elevated threshold is not reached, and the security system does not go into alarm.

These are just a few examples showing how sensor data fusion technology can work. There are innumerable scenarios where it comes into play to catch real intruders while minimizing false alarms.

In addition to the sensor technology described above, there are other sensors that play an important role in intrusion detection. A description of these follows.

Some detectors with temperature sensors simply increase sensor gain as room temperature increases. This gain increase continues linearly as the room temperature exceeds the expected surface temperature of an intruder (33.3°C). Thus, the chance of false alarms climbs right along with the room temperature.

With advanced detectors, the sensor gain increases as expected, but only until the room temperature reaches 33.3°C. Using two PIR sensors with multiple high-quality lenses, the signal-to-noise ratio can be increased only within that narrow temperature band. Once the room temperature exceeds the surface temperature of an intruder, the sensor gain decreases again to minimize false alarms.

Anti-mask technology alarms when an intruder attempts to defeat the detector by masking it with infrared-blocking material, such as paper, tape, film or spray. Typically, an intruder employs these strategies during normal business hours when the security system is disarmed, then returns later with the knowledge that the motion detectors are compromised.

Multi-point anti-mask with integrated spray detection technology recognizes masking attempts from black paper, aluminum and acrylic sheets, white polystyrene foam, clear self-adhesive vinyl, spray-on plastic skin, clear lacquer (brush applied), spray paint and more. This is accomplished with the following technology.

Bounce-Back technology determines if the detector is covered or blocked by an object, such as a shoe box or a piece of paper. With bounce-back technology, the detector creates a bubble of infrared energy extending approximately 30 cm in front of the detector. This bubble radiates from the IR emitter. If the detector is blocked, an above-normal level of IR energy reflects back through the detector’s lenses. The detector uses multiple IR photodiodes to detect the extra IR energy levels, and then sends a trouble signal to the security system indicating that someone masked the detector.

Retro Reflector technology determines if someone attempts to compromise the detector with a sprayed-on material, such as paint. The detector’s LED light pipe contains the Retro Reflector’s advanced multi-prismatic structure. In normal conditions, the Retro Reflector structure reflects IR energy back into the detector where it is detected by a dedicated IR sensor. When the prismatic structure is coated with a spray material, the reflective properties of the prisms are negated, allowing the IR energy to pass through the prisms and out of the detector. A dedicated IR photodiode senses the reduced reflected IR energy level and then sends a trouble signal to the security system.

Through-the-Lens technology determines if a material is placed directly on the detector lens, such as tape or any other IR-opaque material. The detector emits IR energy back upon itself from two specialized prisms located at the bottom of the detector. If the lens is masked, a photodiode receives reduced IR energy levels. The detector then sends a trouble signal to the security system indicating that someone masked the detector.