ORACLE SERIES 2E, 2EC, 4E, 4EC, 4H
Operations Manual
Eberle Design Inc.
Page 3
2.1.2 SENSITIVITY
There are twenty selectable sensitivity levels per channel. The DEFLECTOMETER
®
Pie
Graph, DEFLECTOMETER
®
Numeric Value and a DEFLECTOMETER
®
Streaming Graph,
make it easy to set-up and optimize sensitivity for each channel. Sensitivity can be selected
from the “SET UP” or “QUIK SET” menus, to optimize vehicle detection on varying loop and
lead-in configurations. Sensitivity is stated in terms of
∆
L/L [i.e. as the minimum percentage
change in the total inductance (loop plus lead-in) to which the unit will respond at the given
level.] See section 3.2.1.
Sensitivity
∆
L/L
Sensitivity
∆
L/L
20
0.0035 %
10
0.113 %
19
0.005 %
9
0.160 %
18
0.007 %
8
0.226 %
17
0.010 %
7
0.320 %
16
0.014 %
6
0.453 %
15
0.020 %
5
0.640 %
14
0.028 %
4
0.905 %
13
0.040 %
3
1.280 %
12
0.057 %
2
1.810 %
11
0.080 %
1
2.560 %
2.1.3 LOOP FREQUENCY
The LCD screen displays the actual loop frequency to help avoid interference which may
occur when loops connected to different detectors are located adjacent to one another.
One of eight (8) settings (normally in the range of 20 to 60 kilohertz) may be selected via
the “SET UP” or the “QUIK SET” menu options. It is recommended that adjacent loops
have a frequency separation of at least 5 KHz.
2.1.3.1 FREQUENCY STABILITY GRAPH
In the Frequency display mode the LCD screen also displays a frequency stability graph
and Q
∆
f value that allows you to analyze each frequency level to ensure proper selection of
frequency levels. The XY graph displays detector frequency samples with respect to the
reference. The channel reference is in the center of the graph. A variation from the center
of the graph depicts frequency instability on the channel.
Basically a thin smooth graph offers a more optimum frequency selection over a thick or
uneven line. For optimal operation, select the frequency level with the lowest value of Q
∆
f.
For values of Q
∆
f higher than 15-20, the Noise Filter option (see Section 2.1.3.2) should be
considered.
2.1.3.2 NOISE FILTER
For installations where the effects of cross-talk or resulting frequency instability are higher
than normal, additional noise filtering can be applied. Three levels of filtering are provided;
Normal, Maximum, and Off. The Maximum level is intended for installations with a high
level of cross-talk between loops where the frequency separation between adjacent loops
is not adequate for reliable operation. Setting the filter mode to Off is intended only for high
speed applications where minimum response time delay is required.
2.1.4 SENSOR MODES (ORACLE EC SERIES)
The Oracle EC series support three different inductive loop types; normal loop, point probe,
and rail mode. The Normal sensor mode is used with conventional inductive loops. The
Probe mode and Rail mode are for special applications.