Offtopic: By the way, I'm looking forward to buying the um-TRX to play around with. Is it still due to start shipping the new batch in July? Does the standard um-trx work well with GSM or do we have to also purchase the clocktamer?
The UmTRX comes standard with a high quality VCTXO (or optionally OCXO IIRC) based clock source and supports GPS calibration. No need for external clocking.
Cheers,
Sylvain