Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!killer!vector!nobody From: ssr@cos.com (Dave Kucharczyk) Newsgroups: comp.dcom.telecom Subject: Re: Modem noise Message-ID: Date: 13 Dec 88 16:25:15 GMT Sender: chip@vector.UUCP Lines: 30 Approved: telecom-request@vector.uucp X-Submissions-To: telecom@bu-cs.bu.edu X-Administrivia-To: telecom-request@vector.uucp X-TELECOM-Digest: volume 8, issue 200, message 3 In article chen@cunixc.cc.columbia.edu (Bill Chen) writes: >X-Administrivia-To: telecom-request@vector.uucp >X-TELECOM-Digest: volume 8, issue 198, message 3 > >We've been having progressively worsening noise problems on our dial >up modem pool for our PBX. It seems to occur mainly at nights and >consists mostly of "{" characters. These { comes periodically, about 1 >every 30 secs to 2 minutes. [rest of description deleted] I had this problem for a few months when i moved to a place served by a #5 ESS. the problem is that the T1 line between two offices is not synced properly which causes the bit stream to slip (ie the offset between the two clocks becomes greater than one pulse width and a bit is missed). Why this causes "{" to appear I haven't figured out yet. My friend posted something about this (he got them to fix it), so I'll just repost it. dave [the entire message appears in 187...here are excerpts] .........forget to install, or improperly configure a board in the T1 carrier system equipment (this is not the analog switch, but before the switch) called an "OIU board". He didn't know what OIU stood for, but he tells me that it's fairly standard telco terminology. He said that this board provides the clocking for the link going from the analog office to the digital office. Without the board, the T1 carrier system uses a different clocking source (presumably an internal clock within the T1 equipment) which is not always quite in sync with the correct source. That's why things appear to work ok for voice, but not for data......