GTT Canoga C924 Series, Руководство по установке

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Canoga™ Vehicle Detectors
Canoga™ C924X Series Installation Manual
Product Description & Specification – 73
Presence mode (output ON while vehicle is being sensed) is recommended for general detection
applications. Pulse mode (output ON for Pulse Duration at the start of vehicle detection and, for loop
sensor channels, channel is reinitialized if vehicle is continuously detected for Pulse Rephase Time or
longer) is generally only used when a loop covers more than one lane, e.g. it is desired that a vehicle
stalled in one lane will not prevent vehicles from being detected in the other lane(s). When binning is
enabled, count and occupancy will be stored regardless of whether channel is in Presence mode or
Pulse mode.
8.2.23 Recovery Method
This setting applies only to channels that have a Loop as the Sensor Type. Select either Normal or Fast
Recovery using the C900 configuration software. The recovery method chosen applies only when a
vehicle is not being detected. The recovery method may be selected independently for each channel.
When
Normal is selected, the vehicle detector adapts (moves Reference Frequency towards Loop
Frequency when they are not equal) at the Background Adapt Rate. The default adapt rate setting is
0.50 sensitivity threshold every second. A threshold is the amount of inductance change required to
detect a vehicle at the current sensitivity setting. See Table 5-3 Sensitivity Setting Values.
When
Fast Recovery is selected, the vehicle detector adapts instantly to large changes (more than one
threshold) of apparent inductance in the non-call (non-detect) direction, e.g. Loop Frequency
decreases to a value less than (Reference Frequency - Sensitivity Threshold).
Fast Recovery may be desirable for Presence-type detection in detection areas that remain occupied
for hours at a time. This option is
required for each channel set to Pulse mode. It is strongly
recommended for a channel configured for Max Presence. Similarly, it is normally recommended
that Max Presence be configured for channels placed in the Fast Recovery mode. Fast Recovery mode
is also
recommended for locations that have frequent power failures.
The disadvantage of Fast Recovery is that large noise events, particularly lightning storms, can cause
the detection frequency reference to be set at a frequency lower that the sensor drive frequency (loop
frequency) when no vehicle is present. This can result in a call locked in for hours or up until Max
Presence time.
See Section 8.2.16 Max Presence Configuration for more information.
8.2.24 Long-Loop Counting
The Long-Loop Counting feature allows you to collect count and presence data from long loops. A
presence output is provided through the output pins of the detector while the vehicle count data is
provided via the front or rear serial ports of the vehicle detector. A long loop can be defined as an
inductive loop longer than a standard 1.8 x 1.8 meter (6 foot by 6 foot) loop. This type of loop
configuration occurs primarily at intersections.
8.2.25 Loop and Home-Run Wiring
In selected situations multiple types of cable can be used successfully for home-run. However, the
Canoga 30003 home-run cable is designed specifically for this purpose. The cable contains two pairs of
18 AWG, copper stranded, polypropylene insulated wires encased in a water-blocked cable with a
metalized polyester shield covered by a UV resistant high-density polyethylene jacket. The wires are
parallel wrapped at 6 turns per 0.3 meter (1 foot). The cable is rated for 600 V.
Because of the high degree of decoupling inherent in the vehicle detector’s sequential scanning
detection method, this cable can be used to connect two channels of the same vehicle detector to two
different loops. Its stability also allows reliable operation with lead-in lengths up to 762 meters (2500
feet).