Hi Andrew,
On Fri, Jun 04, 2021 at 02:38:06PM +0000, Andrew Back wrote:
limesdr mini does not have a onboard-clock which is good (precise) enough for gsm requirements. there is no input which can easily be used with an external source like a gpsdo. thus there is no realistic way to reliably do gsm with the -mini, sorry.
External clock can be enabled with LimeSDR Mini, but requires moving (soldering) a 0R link and then you always have to use external clock.
yes,that is possible. I tried that, too, some years ago. The bigger problem, as far as I recall, are the extremely stringent clock jitter requirements at this input. There's no on-board PLL anymore, but it was directly the sampling clock of the ADC, right?
In any case, at least as I recall, I didn't manage to get a spec compliant GSM signal out of the LineSDR-mini with that approach using the clocks I had at my disposal at the time.
But in any case, that jitter / phase noise is mostly a conformance related topic and the signal definitely would be good enough to be properly decoded by commercial UE, particularly in a lab setup with otherwise near ideal conditions.
Regards, Harald