Spectrogram
Equipped with option R&S FPH-K15, you can view measurement results in a 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 Spectrum Rider 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 As the spectrogram in the R&S Spectrum Rider runs from top to bottom, the outdated timeline moves down one position, so that the present frame is always on top of the diagram.
Therefore, the sequence of frames is chronological.
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 Spectrum Rider. The R&S Spectrum Rider 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.