Mode measurement

Alvin.Cox at Alvin.Cox at
Thu Dec 14 09:56:37 PST 2006

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This information also included in the minutes of the 12/14 PHY WG call:
To make a mode measurement, create a histogram over the portion of the 
waveform in question, then use the peak value from the histogram, which 
represents the most commonly occurring value.
If a vertical histogram is created on a scope (assuming you want to 
determine the amplitude mode), a graphical representation of the 
distribution of values that occur within the histogram will be displayed. 
The peak value is the mode.
A timing mode measurement may be creating with a horizontal histogram.
The next key element of mode measurements is the placement of the 
histogram on the waveform. The choice is often specified in the associated 
specification. The results obtained vary depending on if looking at a 
histogram that covers the entire 100000 UI of a waveform, or only a 
portion of that waveform.
With regards to the de-emphasis measurement, the mode amplitude value 
would be the average value of the flat area since the portion without 
de-emphasis would be a separate node on the histogram of all measured 
values of the waveform.
Alvin Cox
Seagate Technology, LLC
Tel 405-350-7424
Cell 405-206-4809

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