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/UmTRX@lists.osmocom.org/.
Alexander Chemeris alexander.chemeris at gmail.comJohn, On Sun, Oct 14, 2012 at 12:24 AM, John Orlando <john at epiqsolutions.com> wrote: > On Sat, Oct 13, 2012 at 4:30 PM, Alexander Chemeris > <alexander.chemeris at gmail.com> wrote: >> Hi John, >> >> On Sat, Oct 13, 2012 at 11:11 PM, John Orlando <john at epiqsolutions.com> wrote: >>> On Sat, Oct 13, 2012 at 3:47 PM, Alexander Chemeris >>> <alexander.chemeris at gmail.com> wrote: >>>> Hi Srdjan, >>>> >>>> We're looking into re-purposing UmTRX for LTE and there a few things which >>>> we need to understand better. >>>> >>>> 1. Is it possible to support 15MHz and 20MHz LTE channel bandwidths? To >>>> achieve this we at least need to sample at 23.04Msps and 30.72Msps >>>> respectively. LMS6002D datasheet specifies the maximum I/Q samplerate of >>>> 14Msps, which is not enough. But at the same time, datasheet claims that ADC >>>> and DAC are specified up to 50Msps. How does this fits together? >>> >>> Alexander, >>> Can you provide a reference to where the datasheet calls out a max I/Q >>> sample rate of 14 Msps? The analog low pass filters support a max >>> bandwidth of 14 MHz (which leads to 28 MHz RF bandwidth assuming >>> zero-IF operation)...is this what you're referencing? >> >> The datasheet is not very clear on this topic. I'm referring to the >> following line at the Table 1: >> Baseband Bandwidth 14MHz >> >> Originally I read this line as "digital I/Q bus has limitation of >> 14Msps" and this is what confuses me. > > Yes, this refers to the analog baseband filter bandwidth. Ok, thanks for the clarification. >>> We run the A/D >>> converters in the LMS6002d at sample rates greater than 14 Msps all >>> the time, including 30.72 Msps. >> >> Just to be sure - do you mean you feed RX_CLK and TX_CLK of LMS6002D >> with 61.44MHz clock? It's divided by 2 internally, so if you feed them >> with 30.72MHz clock you actually get only 15.36Msps out of LMS6002D. > > Correct, when running the A/D at 30.72 Msps, the RX_CLK signal needs > to run at 61.44 MHz. Great! In case you know a good 61.44 MHz oscillator with a reasonable price - I would appreciate a pointer. -- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru