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Andrey Sviyazov andrey.sviyazov at fairwaves.ruAlexander. I think that few pulses of LMS hardware reset (LMS_NRST-1 and LMS_NRST-2 pins) will be much easily than all registers checking. BTW, are there reset pulses after power up or not? Best regards, Andrey Sviyazov. 2012/7/19 Alexander Chemeris <alexander.chemeris at gmail.com> > Guys, please keep track of all LMS configuration values which are not > set to default during power on and we'll add them to our manual > initialization script. > > On Thu, Jul 19, 2012 at 6:56 PM, Andrey Sviyazov > <andrey.sviyazov at fairwaves.ru> wrote: > > Sergey. > > I'll play around GPS power and RTC supply, thank you for your help. > > > > Thomas. > > About r0x16 please be sure that sometimes it isn't set to default value > > after power up (I saw it few times). > > Also I think that possible those bad "power on reset" gave us unstable > > result of LMS autocalibration. > > > > Best regards, > > Andrey Sviyazov. > > > > > > > > 2012/7/19 sergey kostanbaev <sergey.kostanbaev at gmail.com> > >> > >> Which gives ~1.5khz cut-off, that's strange > >> > >> Also I'd check GPS VDD and AVDD nosies > >> > >> > >> On Thu, Jul 19, 2012 at 6:41 PM, Andrey Sviyazov > >> <andrey.sviyazov at fairwaves.ru> wrote: > >>> > >>> 1kOhm resistor and 0.1uF capacitor already exist between DAC and VC > >>> input. > >>> Of course I'll increase capacitance or resistance to be sure about VC > >>> pin. > >>> > >>> Best regards, > >>> Andrey Sviyazov. > >>> > >>> > >>> > >>> 2012/7/19 sergey kostanbaev <sergey.kostanbaev at gmail.com> > >>>> > >>>> No :) But it may cause. > >>>> > >>>> I'd check all the line from FPGA to DAC to VCTXCO because VC pin is > >>>> really sensible to any noise. > >>>> - caused by power supply of DAC. > >>>> - output noise of DAC. > >>>> - algorithm of changing values > >>>> > >>>> At first I'd inspect VC pin at VCTXCO and try to filter it with > cut-off > >>>> frequency 1-0.1 Hz > >>>> > >>>> > >>>> On Thu, Jul 19, 2012 at 6:29 PM, Andrey Sviyazov > >>>> <andrey.sviyazov at fairwaves.ru> wrote: > >>>>> > >>>>> Sergey. > >>>>> Is it really so frequently (32k/s updates at 1pps reference)? > >>>>> > >>>>> Best regards, > >>>>> Andrey Sviyazov. > >>>>> > >>>>> > >>>>> > >>>>> 2012/7/19 sergey kostanbaev <sergey.kostanbaev at gmail.com> > >>>>>> > >>>>>> > >>>>>> > >>>>>> On Thu, Jul 19, 2012 at 6:10 PM, Andrey Sviyazov > >>>>>> <andrey.sviyazov at fairwaves.ru> wrote: > >>>>>>> > >>>>>>> Hi all. > >>>>>>> > >>>>>>> I've found spurs on the LO noise plot at ~33kHz and ~66kHz offset > >>>>>>> when GPS antenna used and position locked. > >>>>>>> This spurs begin grow up when GPS just near to lock position and > >>>>>>> after locking spurs stopped to grow as you can see at picture. > >>>>>>> If thereafter GPS disconnected then noise coming back to normal > plot. > >>>>>>> I think that it is result of 32768Hz clock in the GPS module > EB-230, > >>>>>>> but can't understant how it can impact to 26MHz clock or VCO. > >>>>>> > >>>>>> > >>>>>> As another idea it can be caused by continues GPS correction lead to > >>>>>> DAC changes to the VCTXCO. > >>>>>> > >>>>>>> > >>>>>>> Please tell me something who know. > >>>>>>> > >>>>>>> Thomas. > >>>>>>> Was GPS antenna connected when noise measured like on the picture > >>>>>>> which you sent us (also attached here)? > >>>>>>> I would to know because of anomal peak near to 30kHz offset too. > >>>>>>> > >>>>>>> Best regards, > >>>>>>> Andrey Sviyazov. > >>>>>>> > >>>>>>> > >>>>>>> > >>>>>>> 2012/7/19 Andrey Sviyazov <andrey.sviyazov at fairwaves.ru> > >>>>>>>> > >>>>>>>> Sorry, that was meant to be sent to the mailing list :) > >>>>>>>> > >>>>>>>> Best regards, > >>>>>>>> Andrey Sviyazov. > >>>>>>>> > >>>>>>>> ---------- Forwarded message ---------- > >>>>>>>> From: Andrey Sviyazov <andreysviyaz at gmail.com> > >>>>>>>> Date: 2012/7/18 > >>>>>>>> Subject: LMS TxLO noise > >>>>>>>> > >>>>>>>> Hi Thomas. > >>>>>>>> > >>>>>>>> Here forwarded my last e-mail with noise plots when I stopped work > >>>>>>>> around it at first time, please see below. > >>>>>>>> > >>>>>>>> Please try to play around Tx PLL charge pump current (register > 0x16) > >>>>>>>> for better RMS phase stability. > >>>>>>>> I think we should reach 1 degree or below. > >>>>>>>> > >>>>>>>> Alexander gave me the second UmTRX board and after checking and > >>>>>>>> fixing all known hardware issues I've got roughly the same LO > noise plot. > >>>>>>>> Possible Robin had no time to fixing all of our issues, so check > >>>>>>>> them all please. > >>>>>>>> And also check please what type of TCXO installed on your board. > >>>>>>>> > >>>>>>>> Best regards, > >>>>>>>> Andrey Sviyazov. > >>>>>>>> > >>>>>>>> ---------- Forwarded message ---------- > >>>>>>>> From: Andrey Sviyazov <andreysviyaz at gmail.com> > >>>>>>>> Date: 2012/4/13 > >>>>>>>> Subject: Re: LMS TxLO noise > >>>>>>>> > >>>>>>>> Hi all. > >>>>>>>> > >>>>>>>> There is progress with LMS PLL :) > >>>>>>>> Pictures are attached here. > >>>>>>>> t was discovered that 80 kHz spurs come from Ethernet, or rather > >>>>>>>> from the ET1011. > >>>>>>>> I unknowingly put the choke between transistor of 1V regulator and > >>>>>>>> analog power 1V. > >>>>>>>> As a result, the regulator has become unstable and oscillated 80 > kHz > >>>>>>>> with amplitude of 200 mV, which climbed into the LMS PLL. > >>>>>>>> To correct this problem L46 should be replaced by jumper on all > alfa > >>>>>>>> version PCB's. > >>>>>>>> > >>>>>>>> Also I just played with current in the PLL loop, shown on the > >>>>>>>> picture for clarity. > >>>>>>>> Proved to be the optimal current 1,9 mA (you should write 0x93 in > >>>>>>>> the register of 0x16). > >>>>>>>> But, I think, for the RxPLL will be better use of the current 2.4 > >>>>>>>> mA, because the nearest noises more important for Rx (you should > write 0x98 > >>>>>>>> in the register 0x26). > >>>>>>>> > >>>>>>>> Best regards, > >>>>>>>> Andrey Sviyazov. > >>>>>>>> > >>>>>>>> > >>>>>>> > >>>>>> > >>>>> > >>>> > >>> > >> > > > > > > -- > Regards, > Alexander Chemeris. > CEO, Fairwaves LLC / ООО УмРадио > http://fairwaves.ru > -------------- next part -------------- An HTML attachment was scrubbed... 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