Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site wdl1.UUCP Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!godot!harvard!seismo!hao!hplabs!hpda!fortune!wdl1!jbn From: jbn@wdl1.UUCP Newsgroups: net.dcom Subject: Re: Having trouble with a cable under a Message-ID: <207@wdl1.UUCP> Date: Thu, 17-Jan-85 22:55:14 EST Article-I.D.: wdl1.207 Posted: Thu Jan 17 22:55:14 1985 Date-Received: Mon, 21-Jan-85 04:38:18 EST Sender: notes@wdl1.UUCP Organization: Ford Aerospace, Western Development Laboratories Lines: 12 Nf-ID: #R:fritz:-160000:wdl1:11700008:000:664 Nf-From: wdl1!jbn Jan 17 18:53:00 1985 There are all kinds of neat ways to get polyphase hum, but the real question is whether the hum is common-mode or not. If you short one end of the line together and put an isolated scope across the other end, is the hum unreasonable? If not, all you need is some kind of short-haul modem with good common-mode rejection. You might even be able to get away with sending RS-232 signals down the line if the devices at both ends really implement the spec right, which calls for a -12 to +12 swing with anything in the -3..+3 range ignored. Just some RS-232 booster might be good enough. Get a Glasgal Communications catalog and look for something suitable.