Chapter 10
Measure Mode – Spectrum Tab
Downstream Spectrum
DSAM Help User Guide
Rev. 001
255
Understanding
Downstream
Spectrum Results
The Downstream Spectrum screen displays a 50 MHz or 10 MHz
(zoom) frequency span. Each frequency span is determined by the
center frequency. Within each frequency span, the DSAM forms and
continuously updates a graph with 201 frequency points. The total
Downstream spectrum frequency range extends from 4 MHz to 1 GHz.
Measurement
Information Area
The Measurement Information area (area above the graph) displays
information about the frequency currently selected by the active
marker. The left side of the Measurement Information Area displays
the RBW and VBW values. If Peak Hold is active, a Peak Hold icon is
displayed. If zoom is active, a zoom icon is also displayed. The right
side of the Measurement Information area displays the active marker
frequency.
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 center
frequency and duration of the dwell.
NOTE
Each arrow key press changes the reference setting by a single dB.
The reference level range is -100 to +60 dBmV.
Figure 233
Spectrum – Downstream Spectrum
Graph Information Bar
Marker Information Area
Graph
Measurement
Information Area
21128026 R001 DSAM Help User Guide.book Page 255 Thursday, February 5, 2009 2:02 PM
