LeCroy HDO6000, Руководство оператора

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Operator's Manual
Determining Rise and Fall Times
Once top and base are estimated, calculation of the rise and fall times is easily done (see figure). The
appropriate threshold levels are automatically determined by the instrument, using the amplitude (ampl)
parameter.
Threshold levels for rise or fall time can also be selected using absolute or relative settings (r@level,
f@level) if these parameters are included in your oscilloscope. If absolute settings are chosen, the rise or
fall time is measured as the time interval separating the two crossing points on a rising or falling edge.
But when relative settings are chosen, the vertical interval spanned between the base and top lines is
subdivided into a percentile scale (base = 0 %, top = 100 %) to determine the vertical position of the
crossing points.
The time interval separating the points on the rising or falling edges is then estimated to yield the rise or
fall time. These results are averaged over the number of transition edges that occur within the
observation window.
Rising Edge Duration
Falling Edge Duration
Where Mr is the number of leading edges found, Mf the number of trailing edges found, the time when
rising edge i crosses the x% level, and the time when falling edge i crosses the x% level.
Determining Time Parameters
Time parameter measurements such as width, period and delay are carried out with respect to the mesial
reference level, located halfway (50%) between the top and base reference lines or with respect to the
specified level for @level parameters.
Time-parameter estimation depends on the number of cycles included within the observation window. If
the number of cycles is not an integer, parameter measurements such as rms or mean will be biased.
However, only the last value is actually displayed, the mean being available when statistics are enabled.
To avoid these bias effects, cyclic parameters can be chosen, including crms and cmean, that restrict the
calculation to an integer number of cycles.
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