X-GM-THRID: 1239629356776615040 X-Gmail-Labels: rsgb lf Delivered-To: daveyxm@gmail.com Received: by 10.78.172.10 with SMTP id u10cs322729hue; Mon, 18 Jun 2007 15:00:34 -0700 (PDT) Received: by 10.78.97.7 with SMTP id u7mr2557934hub.1182204034905; Mon, 18 Jun 2007 15:00:34 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.google.com with ESMTP id 7si798280nfv.2007.06.18.15.00.31; Mon, 18 Jun 2007 15:00:34 -0700 (PDT) Received-SPF: neutral (google.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1I0PDi-0006Li-Cx for rs_out_1@blacksheep.org; Mon, 18 Jun 2007 22:57:10 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1I0PDh-0006LZ-Sg for rsgb_lf_group@blacksheep.org; Mon, 18 Jun 2007 22:57:09 +0100 Received: from imo-m28.mx.aol.com ([64.12.137.9]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1I0PDg-0004Tg-Us for rsgb_lf_group@blacksheep.org; Mon, 18 Jun 2007 22:57:09 +0100 Received: from GandalfG8@aol.com by imo-m28.mx.aol.com (mail_out_v38_r9.2.) id l.d44.b606035 (43932) for ; Mon, 18 Jun 2007 17:56:05 -0400 (EDT) From: GandalfG8@aol.com Message-ID: Date: Mon, 18 Jun 2007 17:56:05 EDT To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Mailer: 9.0 SE for Windows sub 5022 X-Spam-Flag: NO X-Spam-Score: 0.6 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,NO_REAL_NAME=0.55 Subject: Re: LF: RE: Broad band QRM-500khz Content-Type: multipart/alternative; boundary="-----------------------------1182203765" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.3 required=5.0 tests=HTML_30_40,HTML_FONTCOLOR_BLUE, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE,NO_REAL_NAME autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Status: O X-Status: X-Keywords: X-UID: 1240 -------------------------------1182203765 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 18/06/2007 22:31:47 GMT Daylight Time, Nick.Mclean@foxtel.com.au writes: It should be a fairly simple matter to build some telephone line low pass filters using a handful of inductors and capacitors and fitting to each line as close to the telephone system as possible. Has anyone on the group made such devices before we re-invent the wheel here? ---------------------- I'm not familiar with this particular equipment but have used older Lucent internal exchanges that operated on a 4 wire system, 2 for analogue speech and 2 for system data lines, where filtering the data lines would not have been a good idea. Later Lucent kit went back to a 2 wire system, but one that that was purely digital, the only place voice recorders, for example, would operate was straight off the handset, so again line filtering wouldn't be very helpful. With more and more systems going digital it might be advisable to investigate this particular system further before starting to add any form of filtering to the lines. regards Nigel GM8PZR -------------------------------1182203765 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 18/06/2007 22:31:47 GMT Daylight Time,=20 Nick.Mclean@foxtel.com.au writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000080 size= =3D2>

It should be a=20= fairly=20 simple matter to build some telephone line low pass filters using a handfu= l of=20 inductors and capacitors and fitting to each line as close to the telephon= e=20 system as possible. Has anyone on the group made such devices before we=20 re-invent the wheel here?

----------------------

I'm not familiar with this particular equipment but have used= =20 older Lucent internal exchanges that operated on a 4 wire system,=20= 2=20 for analogue speech and 2 for system data lines, where filtering the da= ta=20 lines would not have been a good idea.

Later Lucent kit went back to a 2 wire system, but one that that w= as=20 purely digital, the only place voice recorders, for example, would= =20 operate was straight off the handset, so again line filtering wouldn't=20= be=20 very helpful.

With more and more systems going digital it might be advisabl= e to=20 investigate this particular system further before starting to add any form o= f=20 filtering to the lines.

regards

Nigel

GM8PZR

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