889-2106-03
Model U-1400 Operations Manual Rev Apr 2020 Page
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of 39
Section 2
General Characteristics
2.1
LOOP FREQUENCY
There are eight selectable loop frequency settings (normally in the range of 20 to 100 kilohertz) per loop input.
The actual loop operating frequency is a function of the loop / lead-in network and the components of the loop
oscillator circuit. The digital display of the actual loop operating frequency for each setting makes it easy to
quickly identify and eliminate crosstalk in the most difficult to configure installations. The frequency display is
typically very stable when the loop is vacant and vehicles are not passing close to the loops. If the reading is
varying by more than ±1 in the last digit, this is an indication of possible crosstalk between loops.
2.2
SENSITIVITY
There are ten selectable sensitivity levels per loop input, plus Continuous-Call and Loop-Off. The sensitivity
levels are designed so that a one level increase actually doubles the sensitivity and a one level decrease halves the
sensitivity. A unique bargraph displayed on the LCD makes it easy to quickly set sensitivity at the ideal level for
any loop / lead-in network situation. (See Section 3.4 for actual detection levels at each sensitivity level.)
C
ONTINUOUS
-C
ALL
: When set to the Continuous-Call state, the Loop Status is continuously in the Call state
regardless of the presence or absence of vehicles over the loop. If the Loop Status Input is assigned to a Vital
Output, the Continuous-Call state will deactivate the Vital Output. The loop oscillator is disabled when in the
Continuous-Call State. This state is indicated by
Call
flashing on the LCD. This option can be selected from
the Sensitivity menu in Program Mode and is useful for checking controller response and other troubleshooting
activities.
L
OOP
-O
FF
: When set to the Loop-Off state, the Loop Status is continuously in the No-Call state regardless of
the presence or absence of vehicles over the loop. If the Loop Status Input is assigned to a Vital Output, the
Loop-Off state will not affect the Vital Output. The loop oscillator is disabled when in the Loop-Off State. This
state is indicated by
OFF
flashing on the LCD. This option can be selected from the Sensitivity menu in
Program Mode and is useful for checking controller response and other troubleshooting activities.
2.3
OPTION 1: LOOP INDUCTANCE DISPLAY
The Loop Inductance Display setting can be toggled
ON
or
OFF
by momentarily pressing either the
(UP) or
(DOWN) pushbutton. When this option is enabled (
ON
), the LCD displays the total loop inductance (actual loop
inductance plus actual lead-in inductance) in microhenries for loop inductance values in the range of 20 to 2500
microhenries. By recording the inductance of the loop / lead-in circuit when it is first installed, the actual
inductance can be compared to the expected inductance to help identify defective loop / lead-in circuits. Loop /
lead-in inductance can be easily estimated using the simple formulas included in Section 8.2 of this manual.
NOTE: Enabling this option activates it for all loop inputs. This option is automatically disabled 15 minutes after
activation or on loss of power.
2.4
OPTION 2: LOOP INDUCTANCE -
∆L/L DISPLAY
The Loop Inductance -
ΔL/L Display setting can be toggled
ON
or
OFF
by momentarily pressing either the
(UP) or
(DOWN) pushbutton. When this option is enabled (
ON
), the LCD displays the percentage of
inductance change (-
ΔL/L value) during the Call state. To facilitate
the viewing of the maximum amount of
change in the -
ΔL/L value while traffic is in motion over the detection zone, the channel holds the peak
-
ΔL/L
value for a period of two seconds.
NOTE: Enabling this option activates it for all loop inputs. This option is
automatically disabled 15 minutes after activation or on loss of power.
2.5
OPTION 3: NOISE FILTER
Each loop input’s Option 3 has four settings ranging from 3.00 to 3.03. When Option 3 is set to 3.00, the option is
disabled (
OFF
), and normal noise filtering is used. When Option 3 is set to 3.01, 3.02, or 3.03 the option is
ON
,
and increased filtering of the loop signal is used to eliminate problems associated with particular types of noise.
Turning this option
ON
when not required can degrade the performance of the detector.
The default setting of this
option is 3.00 (OFF). This option should only be turned ON at the advice of Reno A&E.
NOTE: Each loop can
be enabled independently.
3.00 = 250 milliseconds filter.
3.01 = 1 second filter.
3.02 = 2 seconds filter.
3.03 = 10 seconds filter.
2.6
OPTION 4: DETECTION ZONE TRACKING
Each loop input’s Option 4 has ten settings ranging from 4.00 to 4.08 and 4.10. This option allows
the user to select a detection zone tracking setting that will maintain detection zone occupancy for an
