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System Set-Up
27
VISCAM 1000 Systems
This is different from the older generations of EN-cameras where the image sensors were using “asynchronous
triggers”. This meant that the imaging sensor was waiting for the next vehicle to pass before an image would
be taken!
The selection of External allows the camera to be externally synchronized with a 50, 60, or 72Hz Sync input.
This feature is necessary if one or more cameras needs to be synchronized to an external synchronization
source – for instance to the A/C power frequency in red-light systems, where the traffic light signals use LED’s
which are “pulsed” from the A/C power source. The 50 Hz and 60 Hz should in this case be selected based on
the A/C frequency where the cameras are installed.
4.10
Automatic Triggering and Light Sensing Configuration
This section describes the parameters to configure when setting up for automatic triggering (Vehicle Detector
Trigger) and light sensing (ALC).
4.10.1
Vehicle Detector Trigger Settings
Select “Vehicle Detector” within “External Trigger Source” to enable Vehicle Detector Trigger. The system will
automatically detect moving vehicles in up to two separate lanes. Note that the traffic in both lanes must be
moving in the same direction.
The Vehicle Detector uses a 200-line high detection area that covers the full width of the image. This detection
area is internally split into 9 horizontal detection grids. Each grid can be individually enabled or disabled. When
used in single lane mode, all 9 are used. When in dual lane mode, four grids are used per lane and the center
grid is normally disabled.
The Vehicle Detector properties are located in the Properties window of the camera in section
12: Vehicle
Detector
Figure 29.
Vehicle Detector settings
Below is a short description of the Vehicle Detector parameters:
Shadow Suppression Mode – Disable/Enable shadow suppression. Enabling this feature helps reduce false
triggers caused by shadow. During certain times of day when the shadow is sufficiently dark compared to the
road surface, it could be mistaken as a vehicle by the VD. The shadow can be from a car in the adjacent lane,
or a long shadow cast in front of or behind the vehicle.
Sensitivity - This determines Trigger sensitivity of the system. The range is from .5000 to .9999 – or “Auto”. In
Auto mode the camera automatically adjusts the Vehicle Detector sensitivity based on the current exposure
settings.
The higher the value, the more sensitive the trigger will be. The selection of the setting should be determined
during the initial setup. Default setting is “Auto” and this is the recommended setting for the system, unless
the user application will actively control the sensitivity (no fixed sensitivity value will work correctly for all
light conditions – so active control will be necessary!)
Trigger Line - This determines the location of a “virtual trigger line” which in fact is the center line of a 200
lines high “Vehicle Detection Area” inside the image. It is specified as the line number of the center line
measured from the top of the image and down to the center line of the “Vehicle Detection Area”. The range is
from 350 to 1702 (default).