SKYROS Corporation VideoNet 8.4 User guide
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Sabotage detector
In video surveillance systems rather often a problem of detecting lost of so called
“useful signal” appears. To solve this problem in
VideoNet
system there is
sabotage detector
, which in real time analyses contrast change of local areas of
frames from video stream from camera-detector.
Sabotage detector
automatically
selects frame areas, by which contrast change over time should be evaluated. If
the contrast change in these areas exceeds some relative threshold, sabotage
detector makes a decision about useful video signal lost.
Sabotage detector
can identify the following situations:
• camera switching off a power source;
• focus shift;
• objective covering or light-striking;
• partial signal lost;
• camera turning;
• video image noisiness is more than expected value.
Sabotage detector
is
insensitive to atmospheric precipitates (such as snow),
objects moving, camera small fluctuation and video signal brightness strong
fluctuation, which as a rule appear at signal hardware automatic gain control
(AGC) operation.
Attention!
For
sabotage detector
correct working it’s necessary that the
video scene have contrast image on it. For example, if camera directed to one-
color, evenly illuminated wall, then
sabotage detector
won’t be able to identify,
whether the camera is in-focus or not. If you redirect camera to some object
in the guarded room, for example, a lamp, then
sabotage detector
will work
correctly.
VideoNet
system enables you to configure
alam message
displaying on the status
panel (refer to
4.1.6
section) in case of detecting sabotage by camera. Also you
can configure necessity to register alarm message confirmation by an operator in
the Event log. This enables you to control operator’s attentiveness and to
reconstruct an accident scene (refer to
3.7.2.10
section,
«Event from detector by
camera»
).
• Audio detectors
Audio detector
At different areas of guarded object constant noise level can differ according to
specificity of each room.
VideoNet
system enables to configure
audio detection
parameters for each microphone according to noisiness of the room, where it is
located. You can create a number of
audio detection presets
for each microphone,
set a maximum permissible volume and a maximum permissible duration of
extraneous noise
.
Audio detector preset
Audio detector
preset
determines audio detection parameters: thresholds for
volume
and
duration
of audio signal from microphone.
If audio signal
volume
exceeds threshold value, specified in
preset
, and if audio
signal
duration
exceeds operating time, specified in preset properties, then the
audio signal will be detected by the system as an
extraneous noise
.
Thus, you can configure
motion detector
,
left objects detector
,
adaptive objects
