Date: Wed, 9 Feb 2000 06:45:09 +1000 From: "Doug Young" <dougy@gargoyle.apana.org.au> To: "Bob" <bob@home.windsong.net>, <freebsd-questions@FreeBSD.ORG> Cc: "Bob" <bob@home.windsong.net> Subject: Re: weird problems Message-ID: <087801bf7275$641fd0d0$827e03cb@ORACLE> References: <Pine.BSF.4.10.10002080749480.46363-100000@home.windsong.net>
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Been there done that but I would have thought that US phone lines were of decent quality instead of the "barbed fencing wire strung between trees" type we have in OZ :) When people complain about weird data transmission issues here our local phone company Tel$tra always trots out the standard line "we only guarantee data transmission to 2400bps" so one has to have connections there to get anywhere. I've had a LONG history of complaining about problems there, starting with the erstwhile Frank Blount (ex AT & T) when he was CEO of Tel$tra, so now I at least know the ropes .... anyway to cut a long story short there are two really common issues we find here in OZ The most common is the "zellweiger" tone injected into the power cables to allow remote control of the off-peak relays for stuff like hot water systems. Many of the phone & power cables here are installed in close proximity so induction is a real problem. A variation of the induction issue is found where phone lines are close to the high voltage supply for electric trains ... although it appears this is only a problem in certain states (poor shielding or something I guess). The problem typically occurs on the hour or half hour, is simple to test, and can be resolved by use of a special filter. A second problem area is intermittent high resistance in local phone cables .... possibly a very old cable thats been subjected to stress / damaged insulation. This can be extremely difficult to locate as one can guarantee that the problem won't surface when its tested, and for that matter the standard testing procedures used in OZ are designed for voice transmission, not data. Judging from the symptoms you have reported, it sounds very similar to a number of instances here where the phone wires themselves were eventually found to be the cause ..... there are diagnostic tests that can be used to test data transmission on PSTN cables, but Tel$tra keeps them a very well kept secret here unless a subscriber really screams the roof down. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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