BS-11 PLL clock source / calibration

[Harald Welte]

On Wed, Apr 08, 2009 at 07:44:02PM +0200, Dieter Spaar wrote:

> The BS-11 takes the clock from the E1 line as reference. So you somehow
> have to make sure that this clock is stable and accurate. If you don't
> use another ISDN line, you have to generate a stable and accurate clock
> for the E1 card yourself.

Dieter, what I just found out is that the LI object has a user-configurable
setting, where we can force it to be stand alone or locked to the E1.

We could add this setting to the bs11_config program so people can try
if their E1 clock or their [10 years uncalibrated] BS11 internal oscillator
is better.

What do you think?

> Another approach might be to calibrate the BS-11 internal oscillator,
> this can be done by software. However it is not yet sure if this will
> solve the problem in a reliable way, also I have not yet found a way
> to measure the BS-11 clock without opening the case.

I'm quite sure there must be an option to do this externally.  The internal
oscillator must be calibrated every two years, and I'm sure they do this
without opening the case (in the field...)

Regards,
-- 
- Harald Welte <laforge at gnumonks.org>           http://laforge.gnumonks.org/
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