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KIMBARQ (TechnicalUser) (OP)
10 Sep 04 11:47
Is there anyone that can explain D4, ESF, AMI & B8ZS to me as if I were an 8 year old.  Or point me to a document that could do the same.


Helpful Member!  SYQUEST (TechnicalUser)
10 Sep 04 12:28
Hi kimzymes,

In the T1 transmission system these terms describe protocols and parameters: D4/SF  & ESF = are the framing formats of the digital signal. D4 and SF are the same thing, stands for Superframe. ESF stands for Extended Superframe. AMI and B8ZS are line code parameters. AMI stands for Alternate Mark Inversion, in relation to framing only allows 56kb channel bandwidth. B8ZS stans for Bipolar Eight Zero Substitution, in relation to framing allows 64kb clear channel bandwidth.

There are many sources that provide reference and tutorial info on the T1 transmission system, one that comes to mind is BellCore/Telcordia. You might do a "Google" and find some good information. Also companies like Tellabs or Telecommunications Techniques Corp(TTC) in the past had some tutorial stuff.

Hope this helps!

Helpful Member!(2)  jerryreeve (Vendor)
10 Sep 04 12:42
a good primer:

another is

let us know if you could use some more detailed info.

If voting could really change things, it would be illegal.

Communications Systems Int'l

SYQUEST (TechnicalUser)
11 Sep 04 5:06
Hi jerryreeve,

Those two links are very good! I downloaded them to refresh my brain every now and then. The RBOCs used to make available some "Tech Pubs" covering the same thing years ago. But I don't know if they are still available. Even though they might be too technical for some, those are the facts of T1!

Just an aside, Quabbin Cable ( has some excellent info on cable for T1 applications and how to do it RIGHT!

jerryreeve (Vendor)
13 Sep 04 10:25
Yes, even if looking at the date of last update makes you wonder what is new about t-1 circuits, it is still the basis of how we send data.

If voting could really change things, it would be illegal.

Communications Systems Int'l

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