Path: utzoo!attcan!uunet!prindle@nadc.nadc.navy.mil
From: prindle@nadc.nadc.navy.mil (Frank Prindle)
Newsgroups: comp.sys.cbm
Subject: Analog loopback mode of a modem
Message-ID: <POSTNEWS23940@NADC.NADC.NAVY.MIL>
Date: 28 Sep 90 02:11:47 GMT
Sender: prindle@NADC.NADC.NAVY.MIL
Lines: 11

Analog loopback is a test mode in which the modem goes into originate mode
on its send half, and answer mode on its receive half, thereby talking into
its own ear, so to speak. A properly functioning modem thus tests all of
its circuits, both analog and digital, by echoing each transmitted character
back to its received data. Not a wholly useful mode for normal operations,
it is reserved for testing a potentially defective modem.  Since AL mode will
cause the modem to drop carrier out the phone line, you generally cannot
select this mode if the modem is off-hook.
Sincerely,
Frank Prindle
Prindle@NADC.navy.mil