[time-nuts] Frequency from telco

Hal Murray hmurray at suespammers.org
Sun Sep 24 16:19:20 EDT 2006

Has anybody tried using the phone company as a frequency reference?

Are the telco master clocks locked to GPS or national frequency sources?  Or 
do they just use their own Cesium box?

Is that a useful way to get a good clock without a GPS antenna?

I worked with T1 many years ago.  It wouldn't be hard to extract a signal to 
feed to a PLL.

Has anybody done that and collected data?  I'd expect lots of short term 
jitter and wander but the long term should be pretty good.

Does anybody know how DSL works?  If I poke around with a scope in my DSL 
modem/router, will I find a clock locked to the telco's master clock?

How many different versions of DSL are there?

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