Talk:Bit error ratio

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Contents 1 Test time 2 Bit error rate 3 Good connection? 4 Equation terms defined?

[edit] Test time

How long would it take to test a 56kb/s modem connection? I estimate several days.

--TerrorBite 30/1/06 13:03 AEST

It depends on the error rate and the data rate. A rough rubric is to transmit 10-times the inverse of the expected BER. For example, if you have 1E-6 (one out of a million) BER, then test 10 million bits. This should provide about 10 errors, which is enough to make the calculation of BER have some significance. You need a significant number of errors to have confidence in the BER. Most people expect modem connections to be error free, which is technically impossible to measure. Therefore, a quasi-error free level, such as 1E-9, or one error in a billion, is used. How long would it take to communicate 10 billion bits on a 56kb/s modem connection? About 48 hours. (Jim Waschura, SyntheSys Research, Inc.)

[edit] Bit error rate

Isn't it supposed to be bit error rate? I have never heard the term bit error ratio. I tried to move the page but it was unsuccessful.

These are synonymous terms. Each are used in different contexts. (Jim Waschura, SyntheSys Research, Inc.)

berriz (talk) 13:48, 25 November 2007 (UTC) I was wondering the same thing, so I searched both terms in the wikipedia search box. I found out that they are not synonyms precisely, and although I'd never heard the term "bit error ratio" before either, it's easy to conclude that 'bit error ratio' is actually the most correct name for that relation, since it's unitless. A 'rate' is a specific type of 'ratio'.

[edit] Good connection?

Isn't it presumptuous to say "On good connections the BER should be below 10-9."? A good connection is a subjective decision...

[edit] Equation terms defined?

The equations are a little too vague for me. When measuring the BER in a real system, what numbers do you "plug in" to the equation? (And which equation should you use?) I think I can figure out symbol time and sampling time (though I'd like them clarified to be sure), but I have no idea what "bit energy" etc. are. Could someone please clear this up with a specific example? Thanks!