Teledyne LeCroy QPHY-UWB - Manual (Page 14)

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QPHY-UWB-OM-E Rev C
SPECTROGRAM ANALYSIS
This view displays a spectrogram of the input waveform. Forming a spectrogram does not require UWB
processing, so you can zoom in on the source (as shown below) to any part of a packet. A spectrogram is a 3
dimensional plot in which the power is plotted on the z-axis, as a color-graded intensity, as a function of both
frequency on the vertical axis and time along the horizontal axis. The time scale for the spectrogram is identical as
that for the source waveform. As you zoom in and out on the source waveform, the spectrogram’s horizontal axis
will automatically rescale to track. The following screen-shot shows the spectrogram of a segment of the input
UWB packet on M1. We can immediately see that the band hopping has a sequence of 1,2,3,1,2,3 which we
immediately recognize as TFC 1. On the spectrogram menu we can control the vertical frequency scale that is
looked at as well as the z-axis dynamic range. These controls are described below.
Setting the Center Frequency and Frequency Span
These values automatically default to the Center Frequency and appropriate Span for the band group that is set
on the main UWB menu. This menu allows them to be changed from the default values.