SmarTek Systems SVS-1 User Guide-Part B - Manual (Page 42)

SVS-1 – Detection Zone Sensitivity Parameters
Detection Threshold – Specifies Line Zone detection sensitivity and may be adjusted by changing the Detection Threshold
value . Increasing the Detection Threshold will decrease sensitivity. The Line Zone Detection Threshold default value is
10.0.
The sensitivity parameters for each Line Zone and associated Circle Zone are displayed to the right of the camera image.
Choose a zone by clicking 1 of 30 option buttons in the Zone Select Frame (below the image). The following sections provide
detailed descriptions for each of the Line Zone/Circle Zone parameters.
Detection Enable Time Out (Enable T0 (s)) – Specifies the amount of time that a line zone detection is enabled after a circle
zone detection is made. The circle zone is at the up road end of a line zone, hence, for directional detection, the circle zone
should “fire” first and then the line zone “fires”. Additionally, this parameter specifies the maximum amount of time that
is allowed to pass for a detection on the down road half of a line zone after a detection on the up road half of a line zone.
Again for directional detection, the up road half of a line zone should “fire” before the down road half of a line zone
“fires”. The Detection Enable Time Out default value is 2 seconds.
Note: Setting the Detection Enable Time Out to 221 enables Circle Zone Detection only. When this parameter is set to 221,
the Enable TO (s) label is shown in red.
Detection Enable Threshold – Default value is 2 for Thru lanes, default is 5 for Left turn lanes. All Lanes Det Enable Thr.
Night is 0.
Shadow Edge Width – Default value is 0.
After setting the parameters for a specific Line Zone (and corresponding Circle Zone), the
parameters for all other zones may be set to the same values using the
Set Parameters for All
Zones button. This does not change positions of the zones, just the sensitivity parameters.
Harmonic High Pass Frequency and Detection Enable Thresholds – Specify parameters that are used to fine tune vehicle
presence detection performance, vehicle absent background estimation, and shadow rejection performance. The default
value for the Harmonic High Pass Frequency parameter is 70. The default value for the Detection Enable Threshold
(used during daytime lighting) is 2. The default value for the Detection Enable Threshold-Night (used during low light
conditions) is 0. The Detection Enable parameter is used to reduce false detections of shadows caused by adjacent lane
vehicles. Increasing the value of this parameter, increases shadow discrimination, however, making this value too large
will degrade vehicle presence detection performance.