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RARENOIS.TXT
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1993-04-02
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RARE LINE NOISE PROBLEM CAUSES
On-Line Version
Last Revised: March 25, 1993
Supra Corporation - World Headquarters
7101 Supra Drive SW, Albany, OR 97321
General: (503) 967-2400
Fax: (503) 967-2401
Sales: 7:00am - 5:00pm PST, M-F
(503) 967-2410
(800) 727-8772
Supra Tech Support: 8:00am - 4:30pm PST, M-F
(503) 967-2440 GENERAL
(503) 967-2490 IBM DOS & Other Products
(503) 967-2491 IBM WINDOWs
(503) 967-2492 MAC
(503) 967-2493 AMIGA
Supra BBS........(503) 967-2444 8 lines 24 Hours v.32bis v.42bis LAPM 2-5
CompuServe.......76004,565
BIX..............SupraCorp
America Online...SupraCorp2
GEnie............SupraTech
AppleLink........D2456
UseNet EMail.....supratech@supra.com
------------------------- (Article Begins Here) -------------------------
If you have an older SupraFAXModem with pre-version 1.2H ROM chips, you need
to get a ROM upgrade from Supra instead of using this checklist. To find out
what version ROM chips your modem has, type AT I3 from your telecom software's
terminal mode.
Once you've verified that your ROM chips are version 1.2H or greater, here are
several uncommon line noise problems you may want to consider.
Building Wiring:
Wiring in older buildings can cause line noise problems. There are two such
wiring problems:
1. Lack of "twisted-pair" wiring. Non-twisted pair wiring consists of four
wires: green, red, yellow, and black. Twisted pair wiring consists of a
matched pair of wires: one wire that is colored with a white stripe, and one
that is white with a colored stripe (i.e. white with blue stripe and blue with
white stripe). To solve this problem, you need to replace the present wiring
with twisted pair wiring. Your local telephone company may be able to help
you with this.
2. Routing next to AC power wires. To solve this problem, the phone wire
must be re-routed, away from the AC power wires.
Distance from Telephone Company Central Office:
Another problem is one that you can't easily do anything about. Simply put,
the farther you are from the telephone company Central Office (CO) the more
likely it is that line noise will be introduced into the lines by nearby AC
power lines and other sources. This will most likely be a bigger problem for
people in rural locations. Moving is about the only sure way to fix the
problem.
Magnetic Fields Interference:
You could also experience line noise problems because you have your computer
monitor or a stereo speaker on top of or very near your modem. These devices
can interfere with the modem transformer, despite the modem's aluminum case.
To solve the problem, move the modem away from these devices.
-------------------------- (Article Ends Here) --------------------------
Copyright 1993 Supra Corporation
Supra Corporation, and SupraModem are registered trademarks of Supra
Corporation.
SupraFAXModem, SupraSmartUART, SupraTurbo, and Silent Answer are trademarks
of Supra Corporation.