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Andrey Sviyazov andrey.sviyazov at fairwaves.ruSergey. 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<http://code.google.com/p/umtrx/issues/list?can=1&q=&colspec=ID+Type+Status+Priority+Milestone+Owner+Summary+Modified&cells=tiles>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. >>> >>> >>> >> > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/umtrx/attachments/20120719/dd933190/attachment-0001.htm>