Teledyne LeCroy HDO 4000 Operators Manual - Manual (Page 37)

HDO4000 High Definition Oscilloscope
Pre-Processing Settings
Averaging - performs continuous averaging or the repeated addition, with unequal weight, of successive
source waveforms. It is particularly useful for reducing noise on signals drifting very slowly in time or
amplitude. The most recently acquired waveform has more weight than all the previously acquired ones:
the continuous average is dominated by the statistical fluctuations of the most recently acquired
waveform. The weight of old waveforms in the continuous average gradually tends to zero (following an
exponential rule) at a rate that decreases as the weight increases.
Deskew - adjusts the horizontal time offset by the amount entered in order to compensate for
propagation delays caused by different probes or cable lengths. The valid range is dependent on the
current timebase setting. The Pre-processing deskew and the Math deskew functions perform the same
activity. See
Deskew Channels .
Invert - Inverts the waveform for the selected channel.
Interpolation - Linear interpolation, which inserts a straight line between sample points, is best used to
reconstruct straight-edged signals such as square waves. (Sinx)/x interpolation, on the other hand, is
suitable for reconstructing curved or irregular wave shapes, especially when the sample rate is 3 to 5
times the system bandwidth.
Noise Filter (ERes) - Enhanced Resolution (ERes) filtering increases vertical resolution, allowing you to
distinguish closely spaced voltage levels. The tradeoff is reduced bandwidth. The functioning of the
instrument's ERes is similar to smoothing the signal with a simple, moving-average filter. Use ERes on
single-shot waveforms, or where the data record is slowly repetitive (when you cannot use averaging).
Use it to reduce noise when your signal is noticeably noisy, but you do not need to perform noise
measurements. It also may be used when performing high-precision voltage measurements: zooming
with high vertical gain, for example. For more information, see
Enhanced Resolution .
Probe Dialog
The Probe Dialog displays probe attributes and (depending on the probe type) allows you to AutoZero or
DeGauss Teledyne LeCroy probes from the oscilloscope touch screen. When a probe is not connected, the
Channel dialog shows only the C1 tab for vertical setup.
Channel dialog with tab for connected probe.
Probe Information on Channel Dialog
After a Teledyne LeCroy probe is connected, it is recognized by the oscilloscope.
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For passive probes, attenuation is automatically set, and these fields are disabled on the Channel
setup dialog.
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For active voltage and current probes, an additional tab with the probe model name is displayed to
the right of the C1 tab. Click on the tab to display the probe dialog.
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