Return-Path: Received: (qmail 14826 invoked from network); 5 Dec 2002 00:54:19 -0000 Received: from netmail01.services.quay.plus.net (212.159.14.219) by mailstore with SMTP; 5 Dec 2002 00:54:19 -0000 Content-Transfer-Encoding: 8bit Received: (qmail 14898 invoked by uid 10001); 5 Dec 2002 00:54:16 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: from post.thorcom.com (193.82.116.70) by netmail01.services.quay.plus.net with SMTP; 5 Dec 2002 00:54:16 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.10) id 18JkGc-0006Bj-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 05 Dec 2002 00:53:26 +0000 Received: from [209.226.175.4] (helo=tomts16-srv.bellnexxia.net) by post.thorcom.com with esmtp (Exim 4.10) id 18JkGb-0006Ba-00 for rsgb_lf_group@blacksheep.org; Thu, 05 Dec 2002 00:53:25 +0000 Received: from lsk.sympatico.ca ([216.208.85.176]) by tomts16-srv.bellnexxia.net (InterMail vM.5.01.04.19 201-253-122-122-119-20020516) with ESMTP id <20021205005317.FGHB15542.tomts16-srv.bellnexxia.net@lsk.sympatico.ca> for ; Wed, 4 Dec 2002 19:53:17 -0500 Message-ID: <5.2.0.9.0.20021204193347.00a8d3f8@pop2.sympatico.ca> X-Sender: b1aemm59@pop2.sympatico.ca (Unverified) X-Mailer: QUALCOMM Windows Eudora Version 5.2.0.9 Date: Wed, 04 Dec 2002 19:52:01 -0500 To: rsgb_lf_group@blacksheep.org From: "Larry Kayser" In-reply-to: <006e01c29bd5$724a3380$09dc9384@jka> References: <036201c29bcc$641d4a30$0101a8c0@athlon> <3DEE6227.7060107@virgin.net> MIME-Version: 1.0 Subject: LF: Re: ADSL EMC with LF operation? Content-Type: text/plain; charset=us-ascii; format=flowed X-Spam-Status: No, hits=-0.5 required=5.0tests=IN_REP_TO,REFERENCES,SPAM_PHRASE_00_01version=2.42 Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Greetings All. Maybe I can add a tiny bit of information to this discussion. Back when we started ADSL with the HDSL work in 1987 we quickly learned that the UK had a special problem (through the work of British Telecom) because of the very wide use of QUAD wire in the distribution plant. QUAD was four wires twist wound uniformly together rather than two pairs, each twisted independently. This caused the much modified ISDN (2B1Q and 4B3Q codes) based HDSL/ADSL and the multi tone modes (now almost the universal way to go) to have a special lower bit rate option for use in the UK. I was able today to find one of the current popular ADSL chip sets, in this case a multi tone type, and I see a four pins out of well over a hundred that "implement the UK option" so this must still be an issue in the UK. At the end of the day, this means the UK will have a large extra power bulge at the very low frequencies. Beyond this, there were tests done in 1990 that showed the proposed 2B1Q and multi tone models would not reach any where close to the range on UK QUAD wiring. One final point, if you doing the ADSL setup yourself. The North American ADSL/HDSL systems are largely line powered. It takes a major effort to deliver 1W of DC to the far end of a long local loop so they regularly see both sides of the 120VDC office battery for a total of nearly 250 V DC on the loop from the central office. This can cause some very strong reactions when ones fingers get into the stuff so if your doing it yourself it is best to be careful, many of us have forgotten how to live with higher voltages with all this 5 and 12 v stuff hi. Good Luck.... Larry VA3LK