Clock from phone

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Dario Lombardo dario.lombardo at
Tue Jul 3 13:08:02 UTC 2012

On Tue, Jul 3, 2012 at 1:44 PM, Sylvain Munaut <246tnt at> wrote:
>> In some past post of the ML, I've read that someone was trying to get
>> the GSM 10MHz clock reference from the motorola phones.
>> This aimed at feeding usrp with a stable reference, if I'm not wrong.
>> Anything new this side? This would be extremely useful if GPS signal
>> can't be got but GSM cell can.
> 1) It's not 10 MHz but  26 MHz

Mmm... but the front panel of usrp is fed by 10 MHz/1pps... isn't it?

> 2) Yes it works, but you can't feed the USRP directly, you need to
> multiply it by 2 (using a PLL chip) to get 52 MHz for the USRP.

Can you provide some link to read something about it?

Don't you think that this way could be much more preferrable than the
GPS way, if USRP is under GSM coverage? I mean: the clock from GSM is
next to us... why just don't use it? Probably there's something I'm
missing, since this approach is much less used than GPS clocking...

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