[asterisk-users] ISDN config: LBO values

[Tilghman Lesher]

On Sunday 16 May 2010 17:32:09 Jaap Winius wrote:
> Quoting Tilghman Lesher <tlesher at digium.com>:
> >> The value selected should almost always be zero. However, if the cable
> >> is of a significant length, another value must be selected, but which
> >> one? There are two columns: CSU and DSX-1. When is it appropriate to
> >> use the one or the other to determine the correct LBO value?
> >
> > Each LBO value is a different amount of loss to be expected on the
> > line, and therefore the signal is amplified a commensurate amount.
> > What it really comes down to is what works for you.
>
> That's the usual approach, but if I was still happy with it I would
> not have asked the question. According to the manual, the values are
> found in a table, but what good is that if you can't make any sense of
> it?

http://www.digchip.com/datasheets/parts/datasheet/222/82V2088-pdf.php

See pages 17-18 of the associated PDF.  While this is not the T1 framer chip
used, the values are identical, which leads me to believe that these values
are actually industry standard.  The values used are merely inputs into the
firmware and the T1 framer does the rest.  BTW, you can find the datasheet
for the actual T1 framer chip, but it's less helpful than the one above.

-- 
Tilghman Lesher
Digium, Inc. | Senior Software Developer
twitter: Corydon76 | IRC: Corydon76-dig (Freenode)
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