Technology Notebook

T1 Terminology::Line Parameters

AMI = Alternate mark inversion - line coding that provides 56K channels (the other 8 K is for "overhead.")
BPV = Bipolar violation
B8ZS = Bipolar eight zero substitution = framing mechanism using intentional BPV's to encode "overhead" for "clear channel" T1's.
"Clear channel coding" = 64K channels (A T1 has 24 channels) = B8ZS
ESF = Extended Super Frame, a DS-1 framing format of 24 frames. In this format, 2 Kbps are used for framing pattern sequence, 4 Kbps are used for the Facility Data Link, and the remaining 2 Kbps are used for CRC
D4 = Fourth generation digital channel bank = "Super Frame"
DS-1 = Digital signal, level 1; 1.544 megabits per second, the North American standard = T1
Choices for T1 configuration:
- ESF or D4, if EMS choose ANSI or non-ANSI
- B8ZS or AMI
-LBO="Line Build Out" - a configurable attenuator at the CSU to adjust signal to a lower level. This may be necessary for "short" connections in which the voltage may be too high.
Resources
http://www.dcbnet.com/notes/9611t1.html Tutorial
http://www.laruscorp.com/t1tut.htm It's main topic is repeated T1 lines, but has excellent foundational materials and is very well presented.
http://www.lucent.com/livelink/162120_Whitepaper.pdf Encoding, Encapsulation, Management