Jump to content

B8ZS: Difference between revisions

Add links
From Wikipedia, the free encyclopedia
Browse history interactively
← Previous edit
Content deleted Content added
VisualWikitext
I realize now what the author was trying to show.
m Twinkle glitching
 
(23 intermediate revisions by 14 users not shown)
Line 1: Line 1:
#REDIRECT [[Modified AMI code#B8ZS]]
'''B8ZS''' is an abbreviation for '''binary eight with zero substitution''', which is a method of line coding used in the [[T-carrier]] system which allows full 64 kbit/s per second per channel, though it does not allow for Clear Channel Capability (CCC - 64 Kbit/s)in and of itself. The service would still have to be point-to-point(PTP)and not switched through a digital switching network. The standard is to use B8ZS as the line encoding option when providing PTP circuits and services. The older AMI scheme was implemented in channel cards that always robbed a bit for signaling regardless if the service on that channel was switched or P2P. B8ZS cards can be optioned not to rob that bit.

On a [[Digital Signal 1|T1]], ones are sent by applying voltage to the wire, where a zero is sent by having no voltage on the wire. Sending excessive zeros in a row could cause receiving equipment to lose synchronization with sending equipment, so it is important that such a pattern not be sent.

The original standard of line coding, [[Alternate Mark Inversion]], specifies that there are three states of the line, no voltage is a zero, positive voltage is a one (or mark), and negative voltage is also a one (or mark). Because of the inversion of the voltage for each "mark," or one, sent, the receiving equipment can easily determine the data rate of the line and not lose synchronization.

B8ZS builds upon this, by using violations of this rule to replace a pattern of eight zeros in a row.

<table border="1" width="50%" cellspacing="0" cellpadding="0">
<tr>
<td colspan="8">Original signal:</td>
</tr>
<tr>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">0</td>
</tr>
<tr>
<td colspan="8">B8ZS encoded signal (V=bipolar violation)</td>
</tr>
<tr>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">V</td>
<td align="center">1</td>
<td align="center">0</td>
<td align="center">V</td>
<td align="center">1</td>
</tr>
<tr>
<td colspan="8">Signal Polarity (assuming that the previous mark was negative)</td>
</tr>
<tr>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">0</td>
<td align="center">-</td>
<td align="center">+</td>
<td align="center">0</td>
<td align="center">+</td>
<td align="center">-</td>
</tr>
</table>

B8ZS is used in the North American hierarchy at the T1 rate. When European E1 was developed much later than T1, it was then common knowledge that forcing 'ones' into a DS0 would corrupt data. E1 uses another method called High Density Bipolar Three ([[HDB3]]) code.

[[Category:Line codes]]
[[Category:Line codes]]


{{Redirect category shell|
[[de:B8ZS]]
{{R to anchor}}
[[fr:B8ZS]]
{{R from merge}}
}}

Latest revision as of 11:11, 11 August 2022

Redirect to:


Retrieved from "https://en.wikipedia.org/w/index.php?title=B8ZS&oldid=1103892799"