LeCroy DDA 7 Zi series, Руководство оператора

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Operator's Manual
WP700Zi-OM-E-RevA
482
p@lv Period at Level
Definition Calculates the period of each cycle in an acquired waveform
Description
For each cycle in a waveform, p@lv determines the time from the beginning of the cycle as
defined by a user specified threshold and slope to the end of the cycle as shown in the diagram
below.
Parameter
Settings
Selecting this parameter accesses a dialog to set hysteresis, level and slope. A hysteresis value
defines the hysteresis, in divisions. That is, a voltage band is extended equidistantly above and
below the selected level. In order for the signal to be considered valid, and not as noise, the
signal must exceed the upper or lower limits of this band by half the hysteresis-division setting.
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.
nbpw Narrow Band Power
Definition Provides a measurement of the power at a specific frequency for a waveform.
Description
nbpw is the magnitude of the Discrete Fourier Transform (DFT) computed on a waveform at a
specific frequency. nbpw 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 on the DDA is 960*
(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 then the bin width will be:
100/48 = 2.1% of the selected frequency.