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Dr. Spine #44 @3473
Sat Feb 16 12:16:13 1991
MINIMUM LINE TESTING REQUIREMENTS
AS SET BY THE FCC
Your local telephone company is required by the FCC to
provide a minimum level of quality on the lines it maintains
for your use. Many lines do not meet these standards, and so
are a source of considerable noise in the transfer of data
between computers. A noisy line can make it very difficult
to upload or download messages and files to a BBS.
If a sysop complains to the telephone company about line
noise, there is usually only one option offered: line condi-
tioning. This is an extra cost item that they would like to
sell you. However, if their line to your computer meets the
minimum standards, there is no reason you cannot have error
free transfers at 2400 bps and, if an error correcting proto-
col is used, reliable operation at 9600 bps is the norm.
If the telephone company seems reluctant to test your line
and assure that it meets the minimum requirements (and they
will), request that they run the following tests and provide
you with the results. Let them understand that if they do not
comply, you will refer the matter to the FCC. They will NOT
be happy!
The following tests should be run:
1) Frequency sweep. 300 to 3000 Hz
2) Roll off. 500 - 2500 Hz, with -2 to +8 range,
and request 300 - 3000 HZ, -3 to +12 range.
1000 Hz tone loss: -16, 1% in either direction
3) Signal to noise ratio. 24 Db level
4) White noise C, message Dbrnco
5) Envelope delay measurement.
6) Phase jitter. Not to exceed 10%
7) Impulse noise test. Minimum 15 minute count
Don't worry if you do not understand what all these tests
mean, the telephone company knows. These standards are all
available from the FCC upon request. When the lines provided
to you meet these minimums, you will experience reliable,
accurate, and noise free data transfers.