Page 74 of 97
Title FireVu Detector Standalone Installation Manual
NetVu Ltd.
No 1 Thellow Heath Park, Northwich Road, Northwich, Cheshire. CW9 6JB
From this menu the “Dwell” defines a period of time for which the system needs to have detected a
“masking” of the detector before it will alarm. It is
strongly recommended that this is not left set to
zero as this may result in detector masked alarms every time a large object passes within the
detector vicinity. A level of 5 (being 5 seconds) is advised as a minimum.
The “Contrast” column indicates a nu
meric representation of the current contrast within the
detector image. If the detector is masked either fully or partially, this level will drop. This remains
at the level detected when the page is first loaded, and so any changes in the contrast
measur
ement whilst the page is displayed will not be seen. However, selecting the “ Refresh ”
button at the bottom of the page will show if, or how, the contrast level is changing.
The “Threshold” is a user defined level at which, if the detected contrast drops
below it, will result in
a fault alarm.
When setting the threshold level consideration must be taken for how much the contrast level will
vary for each scene throughout the day, as contrast may be affected by lighting levels and may
differ between a colour image under natural light and the same scene but as a mono image under
IR lighting. As a start point, it is recommended that the Threshold be set 3 or 4 points below the
current measured level.
What happens when a masked detector is discovered is define
d by a zone, the “On Mask” column
allows the user to define which zone is activated and the results of that zones activation are then
determined by what it is configured to do.
The “On Mask” column provides a drop
-down menu option enabling you to select a zone to be
activated following masking of the FireVu detector enabling the user to have an output which will
determine which camera has gone into “mask” alarm. By default, this should be set to Zone 20
which is titled “Detector Masking” as detailed earlie
r in this manual.
In the example below, (from selecting “Alarm”> “Masked Cam Det” in the web
-page menu), only
camera 2 has been fully set up for “mask” detection, Zone 20 was selected as a Global Zone for a
masked detection being named “Detector Masking”.
Click the “Save” button when you have finished.