RE: [802.3ae] RE: [802.3ae_Serial] 802.3ae PRBSs are upside down
Tom,
Thanks for pointing this out. I was looking at the Agilent 81250 BERT which
has a box where you can select normal or inverted. Looking at the appendix,
it turns out that "normal" chooses a PRBS that is inverted from the output
of the generator. "Inverted" chooses the direct output of the inverter. That
is, normal chooses the PRBS with a run of n 0s for an order n polynomial and
inverted chooses the PRBS with a run of n 1s.
There is a note to the effect that if you are having trouble getting two
testers to work then try switching the inversion.
Well, you can select between two choices and they are inverses of each
other:
normal = inverted
inverted = not inverted
Charming.
Pat
-----Original Message-----
From: Tom Waschura [mailto:tom_waschura@xxxxxxxxxxxxxxxxxxxxx]
Sent: Wednesday, March 06, 2002 1:59 PM
To: stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
Subject: RE: [802.3ae] RE: [802.3ae_Serial] 802.3ae PRBSs are upside
down
Be careful, the normal pattern for an Agilent 86130A BERT (and probably
other Agilent BERTS) is an inverted polynomial (according to some CCITT
standard). If you select the user interface to invert the output data or
use inverted input data, you then get the PRBS pattern without an inverter.
-----Original Message-----
From: THALER,PAT (A-Roseville,ex1) [mailto:pat_thaler@xxxxxxxxxxx]
Sent: Wednesday, March 06, 2002 1:52 PM
To: Tim Warland; THALER,PAT (A-Roseville,ex1)
Cc: Tom Waschura; stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
Subject: RE: [802.3ae] RE: [802.3ae_Serial] 802.3ae PRBSs are upside
down
Tim,
Normal = not inverted. Some of the BERT manuals I was loooking at use the
labels "normal" and "inverted" for the choice of whether to invert the
signal. The word crept in from there.
Regards,
Pat
You changed your tag line. Personally, I spend a fair amount of time working
for what I want.
-----Original Message-----
From: Tim Warland [mailto:twarland@xxxxxxxxxxxxxxxxxx]
Sent: Wednesday, March 06, 2002 1:41 PM
To: pat_thaler@xxxxxxxxxxx
Cc: tom_waschura@xxxxxxxxxxxxxxxxxxxxx;
stds-802-3-hssg@xxxxxxxxxxxxxxxxxx
Subject: Re: [802.3ae] RE: [802.3ae_Serial] 802.3ae PRBSs are upside
down
pat_thaler@xxxxxxxxxxx wrote:
> That is consistant with what I've seen in the sampling of BERTs I've
looked
> at. They all handle both the normal and the inverted pattern.
What defines a normal PRBS31 pattern?
--
Tim Warland P. Eng.
Applications Engineer
Quake Technologies (613)270-8113 ext 2311
Pray for what you want, but work for what you need.