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sergey kostanbaev sergey.kostanbaev at gmail.comJust use our ClockTamer to see how it works :) On Sun, Oct 14, 2012 at 11:30 AM, Alexander Chemeris < alexander.chemeris at gmail.com> wrote: > Hi Robin, > > Do you mean to use ADF4002 to double the frequency? > > Right now I want a simple solution - just replace the TCXO on UmTRX > from 26MHz to 61.44MHz and see how it works. Doubling the frequency > would require PCB rework and is possible for the next generation of > UmTRX only. > > On Sun, Oct 14, 2012 at 4:18 AM, Robin Coxe <coxe at close-haul.com> wrote: > > Something like the attached Taiten VCTCXO @ 30.72 MHz + ADF4002 Phase > > Detector/PLL synthesizer might work. I have no idea how much the > oscillator > > costs. (The Pletronics oscillator on the UmTRX and the GAPfiller GSM900 > > isn't available at this frequency.) > > > > > http://www.analog.com/en/rfif-components/pll-synthesizersvcos/adf4002/products/product.html > > > > -Robin > > > > On Sat, Oct 13, 2012 at 11:54 PM, Alexander Chemeris > > <alexander.chemeris at gmail.com> wrote: > >> > >> John, > >> > >> 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 > >> > > > > > > > > -- > > Robin Coxe | Close-Haul Communications, Inc. | Boston, MA > > +1-617-470-8825 > > > > -- > Regards, > Alexander Chemeris. > CEO, Fairwaves LLC / ООО УмРадио > http://fairwaves.ru > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/umtrx/attachments/20121014/440155b3/attachment.htm>