The Field View graph continuously updates as each frequency is measured.
This forms a wavy measurement line (trace) across the entire frequency
range. When excessive ingress noise occurs at a specific frequency, the
measurement line develops a peak on the graph.
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.
Viewing Options
Several viewing options are available to assist you with data assessment.
Press the VIEW softkey. Use the arrow keys to choose the menu item
you prefer and press ENTER to make your selection.
- Select Auto Reference to automatically view measurement results
in the best reference setting on the graph (Keystroke shortcut: SHIFT
9). NOTE: For best reference setting results you may have to select
the Auto Reference button more than once (up to three times).
- Select 5 dB/div or 10 dB/div to adjust the vertical resolution
of the graph for the best viewing.
- Select (or deselect) Peak Hold to turn on and off the Peak Hold
function, which persists the highest level trace at each frequency for
improved noise isolation. NOTE: It is recommended to use the Peak
hold option to verify the Return Signal Generator Field View gain/loss.
- Select Reset to manually reset the Peak Hold function.
- Select Spectrum to display the local Upstream Spectrum measurement
mode.
- Select Pause to suspend measurement updates (Keystroke shortcut:
SHIFT 8).
- Use the arrow keys to select Marker A or Marker B as the
active marker, then press ENTER. Use the Left and Right
Arrows to move the marker.