Chapter 10
Measure Mode – Spectrum Tab
Field View
DSAM Help User Guide
Rev. 001
265
Field View measurement mode provides increased troubleshooting
accuracy by allowing you to compare spectrum measurements at the
test point with the current conditions at the headend. In the Field View
measurement mode, the DSAM displays all or part of the return path
spectrum which can be in the 40, 50, or 60MHz range.
Graph
As multiple updates occur, the maximum level trace changes only if
new levels exceed the levels of the current trace. A gray trace shows
you the current data when Peak Hold is on. If Peak Hold is turned on,
it ensures that the highest amplitude at each frequency point over
multiple sweeps is captured. The thick black vertical line is the active
marker; the gray vertical line is the inactive marker and does not move.
Graph Information
Bar
This bar displays the start and stop frequencies as well as the dwell
time and telemetry level.
Marker Information
Area
The Downstream Spectrum measurement mode also contains an area
referred to as the Marker Information Area (area below the graph).
This area consists of the marker name, carrier frequency (in MHz), and
measured signal level for the frequencies which the markers are on.
The black square around the letter A or B below the graph displays the
active marker. The Peak Hold levels and the delta value (in dB)
between the peak.
Viewing Field
View Results
To view Field View results
1
Press the
View
softkey.
2
Highlight one of the following:
–
Auto Reference (Shift, 9)
to automatically view measurement
results in the best reference setting on the graph.
–
5 dB/div
or
10 dB/div
– Enables you to adjust the vertical
resolution of the graph for the best viewing.
–
Peak Hold
– Turns Peak Hold on and off. When Peak Hold is
turned on, it displays the highest level trace at each frequency
for an extended view of the noise isolation.
NOTE
For best reference setting results you may need to press the Auto
Reference button up to three times.
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