Overview
The following is a description of Sensor Switch’s patented Microphonics™ occupancy
detection technology followed by a summary comparison to Ultrasonic occupancy
detection technology.
Sensor Switch Occupancy Detection Technologies
Passive Infrared Occupancy Detection:
All Sensor Switch sensors utilize Passive Infrared (PIR) technology to detect changes in
the infrared energy given off by occupants as they move within a sensor’s field-of-view.
Microphonics™ Occupancy Detection:
Microphonics™ technology uses a microphone inside the sensor in order to “hear”
sounds indicating occupancy in rooms with obstructions, such as bathrooms with stalls or
open office cubicle areas. By using Automatic Gain Control (AGC), the sensor can
dynamically self-adapt to its environment by filtering out constant background noise and
detecting only leading edge noises typical of human activity. Microphonics is only used
in Dual Technology sensors where it is paired with PIR (see next paragraph).
Microphonics is not used by itself in sensors.
Dual Technology (PIR + Microphonics):
Sensor Switch’s Passive Dual Technology (PDT) combines both of these detection
technologies. It requires sensors to first “see” motion using Passive Infrared and then
engages the Microphonics™ to “hear” sounds that indicate continued occupancy. For
example, when an occupant enters a room the PIR detection signals the sensor to turn the
lights on. Now that the PIR has been initially triggered, either another PIR detection or a
Microphonics detection can keep the lights on. Patented by Sensor Switch, Passive Dual
Technology using PIR and Microphonics provides a more reliable and completely
passive alternative to active ultrasonic methods of detection.
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Comparison vs. Ultrasonic Technology
False Tripping:
False tripping occurs when a sensor turns on the lights when no occupant is actually
present. False tripping causes increased lighting run-time (therefore less energy savings)
and also increases the number of lamp cycles which in turn can lead to decreased lamp
life. Sensors that use Ultrasonic technology can not distinguish between occupant and
non-human motion therefore they can be prone to false tripping from air currents,
hanging mobiles, or other building-type movements. An example of this type of situation
is where Ultrasonic sensors turn on a building’s lights regularly during the night
whenever the air conditioning system kicks on. This and other similar occurrences have
been observed in the field and are an example why Ultrasonic technology is not used in
security sensors.
Revised 1/1/2010
www.jsblighting.com.au
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False Tripping cont:
False tripping also results from Ultrasonic sound waves leaving the intended space and
detecting unwanted motion. For example an Ultrasonic sensor in a classroom may sense
occupants in an adjacent hallway. In an attempt to reduce this problem, sensitivity
adjustments are present on Ultrasonic sensors in order to reduce their range as needed.
Proper sensor operation then relies more heavily on the installer as the sensors require
adjustment to function properly. Further, turning down the outer large motion detection
range of a sensor often will turn also down the inner small motion detection range of a
sensor as well; an effect that is not desired.
Sensor Switch’s occupancy sensors eliminate the potential for this type of false tripping.
First, Microphonics technology can not cause a false trip since a detected sound can only
keep the lights on and not turn the lights on from an off state. An occupant must be
detected by the PIR for the lights to turn on and the Microphonics to engage. Second,
because PIR requires line of sight in order to detect motion, occupant movement that is
adjacent to the sensors field of view can not cause the lights to turn on. Finally,
Microphonics is tuned to only hear the type of noises humans create (typing, talking,
rustling papers) and ignore building noises (such as air conditioning turning on).
Potential Interference:
Ultrasonic technology is based on high intensity sound waves being transmitted into a
space. Therefore there is a potential for causing interference with devices like wipe-board
readers (for example the Mimio brand) or even hearing aids (if sensors are outside of
appropriate frequency band). While studies and product modifications have been done to
try and ensure that Ultrasonic frequencies used in sensors do not interfere with hearing
aids, the fact that these sensors are emitting high intensity sound waves prevents the
potential for interference from ever fully be eliminated.
Sensor Switch’s Dual Technology Sensors are completely passive meaning nothing is
emitted into a space. This eliminates all possibility for interference with other devices.
Summary
As the summary above illustrates, the drawbacks of using Ultrasonic technology for
occupancy detection are great. Sensor Switch’s PIR/Microphonics dual technology
eliminates all of these drawbacks and is more effective at detecting continued occupancy.
This claim is validated by over 10 years worth of market application and customer
experiences.
Revised 1/1/2010
www.jsblighting.com.au
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Patented by Sensor Switch, Microphonics detection technology uses a microphone inside of the
sensor to hear sounds indicating occupancy. This technology was designed as a secondary detection
method to Passive Infrared (PIR) for rooms with obstructions, such as bathrooms with stalls or open
office cubicle areas. Referred to as having Passive Dual Technology (PDT), these sensors require
occupant motion to be initially seen by the PIR to turn the lights on, after which occupants can either
be seen (via PIR) or heard (via Microphonics) for the lights to remain on.
Microphonics detection is superior to alternatively used ultrasonic technology in that it provides better
and more reliable occupancy detection performance, requires less power, and is acoustically passive.
Microphonics transmits no sound waves into a space, thus eliminating all potential for interference.
Microphonics is tuned to only detect leading edge noises typical of human activity, (e.g., talking,
typing, rustling papers, etc.) and not building noises (e.g., HVAC rumbles or air currents). Additionally,
automatic gain control (AGC) is utilised to dynamically self-adapt a sensor to its environment by
filtering out constant background noise. Finally, sensors with Microphonics use advanced digital
acoustic filtering. This prevents the prolonged presence of varying noises without any PIR events,
such as leaving a television or radio on, from keeping the lights on. It also filters out sounds with
periodicity, such as consistent ticks from a clock.
What is Microphonics Occupancy Detection?
How Is Microphonics Different Than Ultrasonic
Technology?
What Happens If Microphonics Is Used In A Noisy
Environment?
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Passive Dual Technology occupancy detection using PIR & patented MicrophonicsTM
Line voltage sensors utilise a reversible wiring scheme of two identical Orange wires for
connection to line and load. This patented feature ensures that the sensor cannot be wired
backwards - a condition which causes other brands’ sensors to be damaged.
Sensors are set to a default 10 minute time delay, while other brands use 15 minutes. This
provides for greater energy savings and underscores our faith in our detection abilities.
All device settings are digitally programmed via a series of simple push-button commands
done at the unit. There are no analogue dials or pots, dip switches, or tools required.
Low voltage sensors (both PIR and Passive Dual Technology) draw very low current,
enabling 14+ to be connected to one power pack (compared to <5 of other brands).
Photocells have an Automatic set-point calibration mode that can be run at any time of the
day and in any daylight conditions.
Relay contact protection provides extended relay life (tested to over 400,000 cycles).
Benefits
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MICROPHONICS™
Description
Sensor Switch - Features and Benefits