 998/998EX
Fresnel PIR with Look-Down Zone 
 50' x 50' coverage 
Optional coverage patterns (extra lenses
included)
Horizontal and vertical pattern adjustment
Optional swivel mount bracket
Automatic temperature compensation
Alarm memory and case tamper (998EX)
Alternate polarity pulse count
EZ-Mount features for fast installation
SMD construction
White light filter
High RFI immunity
6 year over-the-counter warranty
The ASC Edge:
High Performance Look-Down Design
Positioning of the lens of the look-down zone is critical to look-down performance.
Typically, a PIR will have its look-down lens as an integral part of the outside housing,
as seen on the left side of the figure. This creates two problems:
1. Detection can be compromised. A lens focuses its infrared energy at a
fixed spot just like a magnifying glass or telescope. For best operation, this fixed spot
in a motion detector is on the pyroelectric elements. When the PCB is moved vertically for
coverage adjustment, this energy will be defocused except when the board is in just one
particular
position. Less energy is collected and detection performance suffers.
2. Immunity to rodents is compromised. The long focal length (the
distance from the lens to the pyro elements) causes the projected beam for the look-down
zone to be small. As seen in the left figure, rodents can fill a large portion of the beam
and generate a false alarm.
Ademco look-down designs overcome both problems by using a shorter focal length lens
mounted very close to the detector as part of the circuit board, as shown on the right
figure. When the PCB is shifted vertically for pattern coverage adjustment, infrared
energy is always focused since the distance between the lens and the elements never
changes. Because the lens is close to the element, the projected beam on the floor is now
large compared to the size of a rodent. Avoid both detection and false alarm problems with
Ademco look-down designs.
998/998EX Specifications:
| Detection Method |
Passive Infrared |
| Coverage |
Standard Wide Angle Lens 50' x 50' (15m x 15m), 90º
Long Range Lens 100' x 10' (30m x 3m)
Pet Alley Lens (998 only) 50' x 70' (15m x 21m), 100º |
| Detection Pattern |
Standard Lens: 18 zones (9 long range, 5 intermediate, and 4 short
range)
Long Range: 5 zones, (1 long range, 2 intermediate, 2 short range)
Pet Alley: 12 zones Detector provides single "downward-looking"
zone with all lenses
(downward-looking window must be masked when using pet alley lens) |
| Pulse Count |
Installer-selectable, 1- or 2-event |
| Detectable Walk Rate |
0.5-5 ft/sec (.15-1.5m/sec) |
| Mounting |
7' to 8' nominal (2.1m-2.5m) |
| Indicators |
Red LED with enable/disable link |
| Alarm Relay |
Form A, N.C. 5A contact rating @ 30V DC. 15 ohm protective resistor |
| Input Voltage |
12 VDC nominal (voltage reversal makes PIR inoperative) |
| Current |
15 mA (non-alarm), 17 mA (alarm) |
| Operating Temp |
14ºF to 122ºF (-10ºC to 50ºC) |
| Operating Humidity |
Up to 95% RH (max.), non-condensing |
| Dimensions |
25/8"W x 43/8"H x 2" D
(67mm x 111mm x 51mm) |
|
