This is merely a historical archive of years 2008-2021, before the migration to mailman3.
A maintained and still updated list archive can be found at https://lists.osmocom.org/hyperkitty/list/baseband-devel@lists.osmocom.org/.
Dario Lombardo dario.lombardo.ml at gmail.comOn Tue, Jul 3, 2012 at 3:27 PM, Alexander Huemer <alexander.huemer at xx.vu> wrote: > On Tue, Jul 03, 2012 at 03:08:02PM +0200, Dario Lombardo wrote: >> On Tue, Jul 3, 2012 at 1:44 PM, Sylvain Munaut <246tnt at gmail.com> 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? >> > There are different revisions of the USRP. Sylvain is talking about the > USRP1, you of a later rev. > The USRP1 has an (unpopulated) direct clock input. > The other USRP revisions have a reference clock input, which is > something different. > You are definitly right. I was taling about N210, which can be fed by reference clock input. >> > 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? >> > See [1,2,3] >> 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... >> > > There are many ways to provide a stable reference clock. A OCXO (e.g. > [4]), a cheap rubidium standard, the clock tamer[5], ... > Every option has up and downsides. > Just the "pirelli" way uses clock from existing GSM network. As said before I think that "reusing" the clock from network could be very useful, but I don't know if it is more difficult than generate the signal itself. Is that possible using motorola phones? Did anyone investigate that possibility?