Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

[802.3ae_Serial] Ideas for fixing stressed receiver sensitivity test



Ideas for fixing stressed receiver sensitivity test, from a discussion of
the serial ad hoc, Wednesday 14 November, led by Tom Lindsay.  Notes by Bob
Zona.  With thanks to all participants for such a constructive approach.

1) Measure crossing height instead of DCD (correlation of crossing height
and DCD may depend on rise/fall time)

2) Is attenuation ~= ISI?

3) Total DJ = DCD + SJ

4) sigma is less harmful than W

5) Separate jittered eye (with fast edges) and vertically closed eye tests

6) Use bandwidth test with lower and higher limits for receiver and
eliminate ISI component of stressed sensitivity test

7) Vertical BERT scan

8) Use swept SJ to test receiver jitter tolerance. Can we develop supporting
evidence that this is sufficient? How do we correlate this with our
transmitter specs?

9) Keep looking for ideas on calibrating equipment for jitter bathtub and
current stressed eye tests

10) Use scope to allocate jitter in stressed test setup during calibration

11) Build a quantifiable stressed source using only measurable or
calculatable components from Piers's matrix.

And a couple of notes from Piers: the green stressed eye shown in the draft
standard illustrates DCD without significant amounts of other DJ.  It was
suggested that a scope shot of a more realistic stressed eye could be used
in the standard.  Tom and Jonathan had slightly different definitions of
DCD.  Maybe we need one of those dictionary lists of what our words mean.

Below the line, I have given the matrix in tab-delimited form which (After
removing the line breaks caused by the reflector) you can paste into a
spreadsheet.  There are six columns.  Also I have attached it as an Excel 4
file.  Let's see if it passes the reflector!

Piers
-------------------------------------------------------
Eye  impairment	Current value	Useful?	Do-able?	Measurable
(quantitatively)?	Quantified source?
SJ LF	<~10 MHz	Yes?	Yes	Yes	Yes
SJ HF >~10 GHz	0.05 UI	for W	Try relative (noise stressed jitter
tolerance) measure like ITU-T?	Yes	Yes?
sigma	0.015 UI	Yes	White noise	Yes? Find a (upper?) bound

ISI (VECP)	e.g. 2.2 (-L)	Redundant with OMA?  If no DCD?	Yes
Accuracy and pattern?	Not yet
DCD	6 ps	How much?  PP thinks 6 ps is too much	Yes?	Look at
crossing height instead?	
OMA		Yes	Yes	Yes	Yes
Other DJ	0.25 UI		Yes	No!	
"W" effective DJ		Yes	By SJ (not all) and other DJ	No

-------------------------------------------------------

Stressed_eye.xls