This isn't for garlic's benefit, as I don't interact or answer questions from people who won't post under their name. Life is too short to waste time on such foolishness. But since he's posting gobs of misinformation to the list, I'll explain for everyone else's benefit. First bit of misleading information is that the control (signalling) bits can somehow maintain ones density. It should be obvious to a anyone that this is impossible as the signalling bits need to have multiple values if they are going to signal anything. The only way the signalling bits could enforce ones density would be if they were always ones, and if the were, they wouldn't actually be able to signal anything. Second problem with the signalling bits is that they only occur every 6th and 12th frames. So even if they were always ones, they would only affect ones density during those frames. So "lots" (8) consecutive zero can and do occur on a CT1 line. Without B8ZS, the framer has to enforce ones density by stuffing ones, this causes a drop in the S/N ratio. (I seem to remember 4db as the figure, but I don't have any reference material in front of me to back that up.) B8ZS is able to handle these strings of zeros by inserting a bipolar violation that the receiver knows to remove. Since B8ZS doesn't have to force ones, it doesn't have the associated S/N degradation of AMI only. So try and get B8ZS if you can. On Sun, 23 Jan 2000, Garlic wrote:
Before you go demand they do something, make sure you are not going to waste your time.
B8ZS is of no help on a CT1. The purpose of B8ZS is to ensure timing by preventing lots of consecutive zeros on the line. This can't happen with a CT1. The control bits in each channel will ensure enough ones density to maintain timing.
-- Aaron Nabil - To unsubscribe to usr-tc, send an email to "majordomo@xmission.com" with "unsubscribe usr-tc" in the body of the message. For information on digests or retrieving files and old messages send "help" to the same address. Do not use quotes in your message.