402 WM-OM-E Rev I
nbph Narrow Band Phase
Definition Provides a measurement of the phase at a specific frequency for a
waveform.
Description nbph is the phase of the Discrete Fourier Transform (DFT) computed on a
waveform at a specific frequency. The result is the phase of the
corresponding frequency sine wave component of the waveform at the
first data point between the parameter cursors. The nbph parameter
calculates one bin of a DFT centered at the frequency provided. The bin
width is 0.105% of the frequency selected if the waveform trace displayed
by the DDA is 960 x (1/frequency) or more in length (i.e., the trace is equal
to or longer than 960 cycles of a waveform at the selected frequency).
Otherwise, the bin width is:
100 / integer[(trace length)/(1/frequency)] %,
where integer[ ] designates discarding any fractional portions in the result.
Thus, if the waveform trace is 48.5 times longer than 1/frequency, the bin
width will be:
100/48 = 2.1% of the selected frequency.
nbph is very sensitive to frequency, and it is important that the frequency
value provided be as accurate as possible if accurate results are to be
obtained.
Parameter Settings Selecting this parameter accesses a frequency setting dialog.
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