To Learn More About Equalization - Agilent Technologies 89410A Operator's Manual

Using Adaptive Equalization (Options AYA and AYH)

To learn more about equalization

Adaptive equalization is a powerful feature that you can use in many
applications. The following paragraphs include additional information that
may help you use adaptive equalization for your application.
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Equalization is available only for Digital and Video Demodulation instrument
modes. Equalization is not available for EDGE measurements when the
EDGE(winRC) measured filter is selected. To use equalization with EDGE
measurements, set the measured filter to OFF.
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The primary application of the equalizer's impulse-response display is for
evaluating multi-path environments. Multi-path environments usually require
longer filter lengths.
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The primary application of the equalizer's frequency-response display is for
evaluating the transmitter or receiver signal-path for errors such as passband
ripple and group-delay distortion. Short filter lengths usually work well for
these types of measurements.
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By default, the equalization filter has a unit impulse response (only one tap in
the filter has a non-zero value and data simply passes through the filter). The
position of the unit impulse is a function of the filter length and is positioned to
provide the most optimum efficiency for most situations. The position cannot
be adjusted.
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The filter length and points/symbol determine the number of taps in the
equalization filter, as follows:
# Taps = (( filter_length − 1 ) times points_per_symbol )) + 1
Press [Instrument Mode], [demodulation setup], [more], [eq filt len] to set the filter length.
Press [Time], [points/symbol] to set the points/symbol.
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Generally, there is no advantage to using more than 2 points/symbol when using
equalization. You may want to use more than 2 points/symbol for better
resolution of such displays as eye diagrams, but the tradeoff is slower
measurement speed.
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To see the channel frequency-response over the entire bandwidth of your signal,
use 2 points/symbol or greater. You cannot see the channel frequency-response
over the entire bandwidth of your signal if you use 1 point/symbol.
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Online help for the equalization-filter softkeys includes additional information.
Select Digital or Video demodulation, then press [Help], [Instrument Mode],
[demodulation setup], [more] and any equalization softkey.
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