Spectrogram
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 vertical axis represents time. Time in the spectrogram runs chronologically from top to bottom. 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.
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 measurement 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.
