The Spectrum Application
FPC1000
63
User Manual 1178.4130.02 ─ 02
Changing the span
Usually, the span that the R&S
FPC1000 selects yields optimal results. But sometimes
you also need to see the spectrum outside the current span to detect other signal com-
ponents that you need to include in the measurement. Therefore, you can adjust the
span to up to ten times the channel bandwidth and hence still be able to see the spec-
trum outside the measurement channel.
1. Press the "Span" key to open the span menu.
2. Select the "Manual Span" menu item.
The R&S
FPC1000 opens an input field to define the span.
3. Enter the span you need.
Note:
The largest possible span for the channel power measurement is ten times
the channel bandwidth. At larger spans, the result of the channel power measure-
ment would be increasingly imprecise, because too few points of the trace would
be in the channel you are measuring.
9.2.3 Working with the Spectrogram Result Display
Access
(measurement menu): "Meas" > "Measurement Mode" > "Spectrogram"
Access
(measurement menu): "Meas" > "Measurement Mode" > "Spectrogram Play-
back"
Remote commands to control the spectrogram:
●
not supported
Available with the optional "Advanced Measurements" application.
The spectrogram result display shows the spectral density of a signal in the frequency
domain and over time simultaneously.
Like other result displays, the x-axis represents the
. The y-axis repre-
sents time. Time in the spectrogram runs chronologically from top to bottom. There-
fore, the top of the diagram is the present. A third dimension shows the amplitude for
each frequency by mapping different colors to every power level.
The color the R&S
FPC1000 assigns to a power level that was measured depends on:
●
The color table you have selected.
●
The spectrogram reference level.
●
The spectrogram level range.
The spectrogram consists of horizontal lines, each one pixel high, that are called
frames. In the default state, a frame is added to the spectrogram after each
.
This means that the amount of data in a frame depends on the sweep time. Because
the spectrogram in the R&S
FPC1000 runs from top to bottom, the outdated time
line(s) move down one position, so that the present frame is always on top of the dia-
gram. Therefore, the sequence of frames is chronological.
Measurements and Result Displays
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