| Dual technology detectors
combine a Passive Infra-red
detector (PIR) and a microwave
(MW) detector into a single
unit. Both detectors have to
be in alarm condition for an
alarm to be signalled to the
control panel. The PIR
detector responds to moving
heat sources, whereas the MW
detector responds to changes
in the observed space. The MW
detector transmits a microwave
signal which bounces around
the room and is received at
the detector. A significant
change in the received signal
triggers an alarm condition in
the MW detector.
Dual technology detectors are
used in situations wher a PIR
unit alone is likely to
produce false alarms -
conservatories, sheds and
outbuildings etc.
The units are wired as a
conventional PIR using 6 core
cable. |
