c.
Ultrasonic sensors: Sensors shall detect intruder presence by
transmitting ultrasonic energy into a protected zone, receiving
the direct and reflected energy, and monitoring frequency shift
between transmitted and received signals. Ultrasonic energy shall
be above 24 kHz and below 30 kHz (nominally 26 kHz). Sensor shall
provide for selective filtering to minimize nuisance alarms due to
external sources of ultrasonic energy. Sensor shall automatically
adapt to changing levels of air turbulence and shall consist of a
control unit and as many transceivers as required to protect a
zone within limitations of the control unit. Ultrasonic system
shall provide a means of indicating an alarm condition at the
protected zone during installation and calibration. This
indication shall be provided with a disabling device within sensor
enclosure. Transceivers shall consist of an adjustable-gain
preamplifier, an ultrasonic-to-electrical transducer, and an
electrical-to-ultrasonic transducer in a single enclosure.
Transducers shall be adjustable in position to allow adequate
adjustment and directivity. Each transceiver shall be capable of
protecting a rectangular volume approximately 6 by 9.2 meters 20
by 30 feet in a zone with an 2440 to 3660 mm 8 to 12 foot ceiling.
Maximum peak power output of transmitter shall not exceed 105 dB
sound pressure level (SPL) at 900 mm 3 feet or greater range.
Transceiver zones shall overlap slightly; particular care shall be
taken to ensure adequate sensitivity in area abundant in
acoustic-absorbing materials such as carpets and drapes. When the
protected zone is broken up by furniture or large objects, it
shall not be possible to traverse the zone undetected by moving
the blind zones created by the objects. Provide each sensor with
sensitivity adjustments. Controls shall be inaccessible to
operating personnel. Sensitivity requirements shall be met with
sensitivity controls set approximately at midrange. System shall
alarm if an intruder moves within the area of protection more than
1500 mm 5 feet at a velocity of 150 mm 0.5 foot per second to
4570 mm 15 feet per second. Sensitivity shall be irrespective of
direction of motion. System shall also alarm at velocities higher
than 150 mm 0.5 foot per second, up to 2440 mm 8 feet per second.
Sensor elements shall be [installed to be self-protecting] [and]
[housed in a tamper-alarmed enclosure].
d.
Microwave sensors: Sensors shall detect intruder presence by
transmitting electromagnetic energy into a protected zone,
receiving direct and reflected energy, and monitoring frequency
shift between transmitted and received signals. When more than
one device is used in an area, devices shall operate on different
frequencies. Provide for selective filtering by the sensor to
minimize nuisance alarms due to moving metal objects such as fan
blades, and venetian blinds, interference from radar, or other
sources of electronic interference. Provide a means of indicating
an alarm condition on the sensor at the protected zone during
installation and calibration. Provide an indicator disabling
device within sensor enclosure. Transceivers shall consist of a
transmitting antenna and a receiving antenna, or a combined
transmit/receive antenna, and an adjustable-gain preamplifier in a
single housing. Provide transceivers with sensitivity
adjustments. Transceiver controls shall permit adjustment of
transmission range and alarm signal threshold. Sensitivity
controls shall be inaccessible to operating personnel.
Sensitivity requirements shall be met with sensitivity controls
SECTION 13703N
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