The FDR graph presents a view of distance on the X-axis and amplitude
on the Y-axis. Your LST-1700 is transmitting signals down the cable and
is looking for RF energy being reflected back. Reflections occur when
there is a change in impedance possibly caused by such things as cable
damage,
A reflection will appear on the graph as a peak in amplitude located at
the distance where the impedance has changed. The amplitude of the reflection
will indicate the severity of the impedance change. For example, a large
reflection will result if the cable is broken or un-terminated.
Using this graph, you can locate faults and determine how far away they
are.
To fully understand FDR measurement results, you should be familiar with
the graph and the viewing options available in FDR mode.
FDR SUB-TITLE BAR (above graph)
This area shall display information about the currently selected settings
as follows:
Velocity of Propagation (VOP)
The VOP is the speed at which signals travel down the length of a cable.
It is determined by the dielectric material used to separate the two conductors
and is usually specified by the manufacturer. NOTE:
The VOP value entered in the Settings display is the displayed VOP value.
Max Precision
The Max Precision is the cable attenuation selected.
GRAPH AREA
The graph presents a view of distance on the X-axis and amplitude on the
Y-axis.
Vertical Distance Marker
You can position the vertical distance marker over a reflection so that
you can pinpoint its distance and amplitude. You can see the marker information
directly beneath the graph. NOTE:
Use the left or right arrows to adjust the distance marker.
Progress Bar (below graph)
Displays status of the measurement cycle.
STATUS INFORMATION AREA (below graph)
This area consists of the following:
- Horizontal status
- Selected dBRL
- Selected Zoom
- Cable Compensation status (ON or OFF) from Settings screen.