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From: jaborn@gemini.bbn.com (Justin A. Aborn)
Newsgroups: sci.electronics
Subject: Recommendation V.35
Message-ID: <60869@bbn.BBN.COM>
Date: 15 Nov 90 16:50:49 GMT
Sender: news@bbn.com
Organization: Bolt Beranek and Newman Inc.
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Does anyone out there have experience with V.35 interfaces.  What
are the real voltages that real equipment uses?

CCITT Recommendation V.35 for a balanced line driver says:

	"When terminated by a 100-ohm resistive load the
        terminal-to-terminal voltage should be 0.55 +- 20% volts
	so that the A terminal is positive to the B terminal when
	a binary 0 is transmitted, and the conditions are
	reversed to transmit binary 1."

However AT&T uses 1.1 volts terminal-to-terminal and claims it is
V.35.  I think AT&T misread the specification years ago; thinking
it said driver outputs should be +- 0.55 volts.  It seems that
the 1.1 V terminal-to-terminal voltage has become the defacto
standard.

Just to make sure it exists somewhere, does anyone out there know
of V.35 implemented with 0.55 volts?

Justin Aborn
617-873-3552