Rohde and Schwarz ZVH-K14 - Spectrogram Measurement Application Option for ZVH

Equipped with the R&S ZVH-K14 spectrogram measurement application, the R&S ZVH can provide a history of the spectrum. This application can be used to analyze intermittent faults or time-dependent frequency and level variations. Specific analyses can be made by replaying recorded data and setting time lines and markers.

The spectrogram result display shows the spectral density of a signal in the frequency domain and over time simultaneously.

Screen layout for the spectrogram

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 ZVH 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 sweep. This means that the amount of data in a frame depends on the sweep time. As the spectrogram in the R&S ZVH runs from top to bottom, the outdated time line(s) move down one position, so that the present frame is always on top of the diagram. Therefore, the sequence of frames is chronological.