I wanted to give you an update on the analysis I did relating the draft 11801-1 SPE alien crosstalk specs vs. IEEE 802.3
- Class T1-A is specified only to the frequency extent of 10BASE-T1L. It would be useful to extend the specifications to at least 66 MHz and possibly 100 MHz to align with 100BASE-T1
(at shorter reaches) and discussions in the IEEE 802.3 Greater than 10 Mb/s long-reach SPE Study Group about a possible 100BASE-T1L.
- Class T1-B has a bandwidth of 600 MHz which aligns with 1000BASE-T1, but the PSAACR-F (alien far end crosstalk) spec does not align with either segment A or optional segment B. It
is substantially overspecified for 100BASE-T1. I would recommend aligning this specification with segment A (since it is close), which is a minor adjustment to the spec. Wayne Larsen suggests that some specification involving length scaling might accomplish
this; however, the PSAACR-F spec in the document is not currently subject to length adjustment.
- Class T1-C would meet the 1000BASE-T1 A specification, but is overspecified both in bandwidth and crosstalk. Similar to the relation between the Class T1-B and 1000BASE-T1 type A,
Class T1-C and 1000BASE-T1 type B link segment specs similarly fails alien fext (PSAACR-F), but seems to require a minor modification, possibly by length-scaling. The bandwidth overspecification is another issue, as the cabling is overspecified for the application
and would be confusing to the user.
None of the classes match to the clause 149 2.5G/5G/10GBASE-T1 specifications, and 2.5GBASAE-T1 would align more in bandwidth with class T1-C at least on the transmission parameters, if not the alien crosstalk parameters.
-george
George Zimmerman, Ph.D.
President & Principal
CME Consulting, Inc.
Experts in Advanced PHYsical Communications
george@xxxxxxxxxxxxxxxxxxxx
310-920-3860
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