From: Neven Pischl ([email protected])
Date: Mon Mar 05 2001 - 19:20:40 PST
SCV EMC Society Meeting
"OPTIMIZING GBIT ETHERNET IDLE PATTERN FOR BETTER EMC PERFORMANCE"
Tuesday, March 13, 2001
The March meeting of the Santa Clara Valley EMC Society will be held at SGI in
Mountain View, 1600 Amphitheatre Pkwy., building 40, in the Presentation Center
above the lobby. The social gathering will start at 5:30 PM, and food and
drinks will be available. The technical presentation will start at 7:00 PM.
You can visit us at:
Author - Todd Knibbe, Agilent SPG
BS+MS in Electrical Engineering from Massachusetts Institute of Technology
1993. Worked for MIT Lincoln Laboratory on satellite free-space laser
communication links 1991-1994. Worked for Hughes Network Systems designing
satellite radio transceivers (DirecTV) 1994-1999. Currently an Applications
Engineer with Agilent Technologies.
Of all the possible data patterns used in a Gigabit-Ethernet system, the Idle
Pattern dominates the EMC emissions. It is typically used as a worst case
scenario for EMC characterization and testing. This is because in many
systems, the steady state Idle Pattern consists of a repeating 20-bit sequence,
causing a very distinct emissions spectrum which can be radiated by high-speed
serial components when no data is being sent. However, the Gigabit Ethernet
standard allows for some flexibility in the implementation of Idle Pattern.
Software/Firmware can be modified to lengthen/randomize the Idle Pattern,
lowering peak emissions and improving EMC compliance dramatically. Reduced
emissions in a multi-port Gigabit Ethernet system using these alternative Idle
Patterns was demonstrated. The 10-Gigabit Ethernet Alliance is already
applying these lessons to reduce Idle Pattern emissions in next generation
10-gigabit Ethernet systems.
GbE Idle Pattern and EMC Performance in GbE systems 8B/10B Encoding
Basic discussion of 8B/10B encoding system used by GbE systems Idle Pattern
Implementation of GbE Idle Pattern using 8B/10B encoding
Initial experiment with alternative GbE Idle Patterns to reduce EMI
EMC Testing of Alternative GbE Idle Patterns
EMC testing with commercial system and alternative GbE Idle Patterns
10GbE Committee Recommendations
Alternative (Randomized) Idle Pattern included in 10GbE standard
Anyone interested in presenting an outline of EMC-related topics may contact
Tom Cokenias ([email protected]) at 650-726-1263.
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