Spectrum Analyzer Mode
R&S
®
Cable Rider ZPH
194
User Manual 1321.0950.02 ─ 07
Equipped with option R&S ZPH-K15, you can view measurement results in a spectro-
gram.
The spectrogram result display shows the spectral density of a signal in the frequency
domain and over time simultaneously.
Like other result displays, the horizontal axis represents the frequency span. The verti-
cal axis represents time. Time in the spectrogram runs chronologically from top to bot-
tom. Therefore, 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
result is therefore a two-dimensional diagram.
The color the R&S Cable Rider ZPH assigns to a power level that was measured
depends on:
●
Color table
●
Spectrogram reference level
●
Spectrogram level range
The spectrogram consists of horizontal lines, each of one pixel height, which is called
frames. In the default state, a frame is added to the spectrogram after each sweep.
This means that the amount of data in a frame depends on the sweep time. As the
spectrogram in the R&S Cable Rider ZPH runs from top to bottom, the outdated time-
line moves down one position, so that the present frame is always on top of the dia-
gram.
Therefore, the sequence of frames is chronological.
1. Press the [MEAS] key.
2. Select the "Meas Mode" softkey.
The R&S Cable Rider ZPH opens a submenu to select the measurement mode.
3. Select the "Spectrogram" menu item.
The R&S Cable Rider ZPH starts the spectrogram result display.
By default, the spectrogram result display consists of two windows. The upper window
shows the measured spectrum as a trace line. The lower window shows the measure-
ment results in a spectrogram. The chronological information in the spectrogram is
restricted by the internal memory of the R&S Cable Rider ZPH. The R&S Cable Rider
ZPH stores 1024 frames or spectrums that have been measured in its memory. As the
height of the display is smaller, some of the data becomes invisible after a time.
Performing Spectrum Measurements
