FORWARD
SWEEP
With forward sweep, DSAM performs simply as a passive analysis receiver.
It does not transmit any sweep pulses or telemetry. The headend transceiver
does all the active work and communicates the headend measurement results
over telemetry to the field DSAM for comparison to the local measurements
on DSAM.
Forward sweep is accomplished with a transceiver and measurement system
in the headend or hub site, such as the SDA-5500 Stealth Sweep Transceiver.
It transmits and measures active sweep points as well as measures reference
carriers. Multiple field DSAMs can be used at the same time with a common
SDA-5500. Typically the headend technician or network engineer is responsible
for an accurate forward sweep plan within the SDA-5500 transceiver.The
following topics explain the user functions available within the Forward
Sweep mode.
Softkeys
Four softkeys on the FORWARD SWEEP screen
provide the following options (same as REVERSE SWEEP screen):
FILE
Save Reference...
Saves the current measurement as a reference file.
Save File...
Saves the current measurement as a static measurement file. NOTE:
When a saved static measurement file is opened, the graph will be one
similar to the live measurement graph.
TIP: To assure exact measurement recording of current display, always
pause (SHIFT 8) measurement updates before saving or printing a measurement
file.
Load Reference...
Proceeds to a work folder associated with forward sweep reference files.
From the work folder select a desired reference file. If the file selected
is not compatible with the current received sweep plan, a message will
alert the user. NOTE: This feature
allows you to display the difference of the live data and the data stored
in the file
When a reference file has been chosen for display, the name of the reference
file appears in the subtitle bar in place of 'REF: NONE'.
The maximum length of the file name is 12 characters. When an additional
file is saved, the file name field in the "save a file" display
will contain the last label saved. This label may be appended, altered,
cleared or simply saved unchanged. If saved unchanged, an "overwrite?"
warning will be displayed that must be acknowledged. NOTE:
Since a reference file is essentially an average of the data obtained
from four previous sweeps, enough traces need to accumulate before a file
can be saved and used as a reference file. Thus, when the forward sweep
screen is accessed for the first time, the subtitle bar initially displays
a cross in place of the reference file name. Once enough traces have accumulated
"REF: NONE" is displayed.
Load File...
Loads a file as a static measurement file.
Clear Reference
Removes reference file from measurement and returns the subtitle bar to
"REF: NONE".
VIEW
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.
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.
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 1 dB/div, 2 dB/div, 5 dB/div, or
10 dB/div to adjust the vertical resolution of the graph for the
best viewing.
Select (or deselect) Zoom to turn
on and off graph magnification. When selected, the Zoom feature produces
a display that has a frequency span that is defined by the position of
the markers in the original non-zoomed view.
Select Pause to suspend measurement
updates (Keystroke shortcut: SHIFT 8).
FORWARD or REVERSE
The third softkey toggles (changes) between FORWARD and REVERSE sweep modes.
Press this soft key to select the opposite direction sweep mode than what
you are currently viewing. If you are testing on directional test points
in the system, you will need both ports 1 and 2 on DSAM connected to the
test points to easily shift back and forth between the two modes.
SETTINGS
Test Point Comp...
Proceeds to the test point compensation configuration screen.
Changes are made and stored within the DSAM Configuration mode.
Telemetry Frequency...
Proceeds to the telemetry frequency screen.
Changes are made and saved within the active channel plan (label viewed
in upper right-hand corner of display).
Sweep Tilt and Limit ...
Proceeds to the sweep settings screen.
Changes are made and stored within the DSAM Configuration mode.