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Jean-Samuel Najnudel - BJT PARTNERS SARL jsn at bjtpartners.comHi Robin, Thank you very much for your help. This could be very convenient. Thanks a lot. Best regards. Jean-Samuel. :-) On Fri, Mar 16, 2012 at 12:08 AM, Robin Coxe <coxe at close-haul.com> wrote: > ** > Hittite is located in Massachusetts about 40 km from Boston. Let me know > if I can help with sourcing components or requesting samples. > > -Robin > ------------------------------ > *From: * Andrey Sviyazov <andreysviyaz at gmail.com> > *Date: *Fri, 16 Mar 2012 02:54:51 +0400 > *To: *Jean-Samuel Najnudel - BJT PARTNERS SARL<jsn at bjtpartners.com> > *Cc: *Alexander Chemeris<alexander.chemeris at gmail.com>; < > gsm-internal at lists.fairwaves.ru>; Robin Coxe<coxe at close-haul.com>; > Project Mayotte<project-mayotte at sysmocom.de> > *Subject: *Re: Selectivity improvement solutions proposal for UmTRX > > Hi Jean-Samuel! > > About ADL5802, you can't use it as Down and Up converter simultaneously. > Also I'm afraid that we can't yet receiving 2 GSM carriers simultaneously. > So lets done single channel first but 2 or more keep in mind for > experiments. > > I try to find better components too. > ADI mixers have internal IF AMP and it is not good in this case. > Components of Hittite are known for me as a very good through my main job. > I'd like to recommend to use any of the next: > for GSM900 > 1/ HMC830LP6GE + HMC483MS8GE + TB0130A. (20.6+4.69+3=$28.29) > 2/ HMC830LP6GE + HMC686LP4E + TB0448A. (20.6+9.67+3=$32.97) > for DCS1800 > 1/ HMC830LP6GE + HMC485MS8GE + TB0130A . (20.6+4.69+3=$28.29) > 2/ HMC830LP6GE + HMC687LP4E + TB0448A. (20.6+9.67+3=$32.97) > By the way, LMS lower limit 0.3GHz as per datasheet. > > About GSM 05.05 specs I still can't understand blocker requirements: > MS spectrum with RBW=200kHz have -65dBc level at 600-1200kHz offset, > therefore blocker MS with -26dBm will be jammer for wanted MS with level > less then -91dBm and noise level of receiver's heterodyne isn't matter in > this case. > I really can't understand why CW levels -26dBm and -16dBm blocking tests > required. > May be it just universal test of heterodyne quality? > > I think we should be reasonable people, and therefore we should use > parameters which really necessary for us. > So, ADRF6601 parameters seems to be quite enough even if it pass only mBS > requirements. > On the other hand, BOM difference between ADRF and HMC's around $20-25 > only and it isn't much for normal BS. > In short, it seems that we should do three options front-end mezzanines: > 1/ without channel preselector for picoBS or nanoBS upto 0.5W/ch. > 2/ preselector ADRF based for microBS upto 2W/ch. > 3/ preselector HMC based for normal BS with 10-20W/ch TMB. > > Please find attached pictures that my simple calculations for RX chain. > Also, please let me know real PA parameters which you decide to use > for TMB. > > Best regards, > Andrey Sviyazov. > > > > 15 марта 2012 г. 4:42 пользователь Jean-Samuel Najnudel - BJT PARTNERS > SARL <jsn at bjtpartners.com> написал: > >> Hi Andrey, >> >> Thank you for your e-mail. >> >> Yes, you are all right. >> >> It think your calculations are good. I just did not knew how hard was the >> GSM macro BTS spec. >> >> I browsed a bit the web and found the GSM 05.05 specs which confirm what >> you say. I also found some similar information and calculations in an >> academic paper which confirm your figures. >> http://www.uta.edu/rfmems/Conferences/2001_SPIE_MicroMEMS/4592-20.pdf(page 5 and 6) >> >> Anyway, I tried to look at other components than the ADRF6601. >> >> I found a quite low phase noise VCO/PLL from Hittite which seems to be >> able to let us probably pass the macro BTS spec or at least the micro BTS >> spec. >> http://www.hittite.com/products/view.html/view/HMC830LP6GE >> >> For the mixer, we may use a separate component like the ADL5801. >> >> Please let me know what you think about these chips. Please do not >> hesitate to let us know some other suggestions if you know or if you can >> find some other components that would have better performances. >> >> Actually, even if the specs are not easy to pass, I still feel quite >> optimistic as it was possible to pass these specs 15 years old components. >> Anyway, if the macro BTS specs are really too hard to pass, we may focus on >> the micro BTS spec. This would already be great to convince the market you >> may be interested in and the performances would be good enough for most >> practical situations in my deployment in Mayotte. >> >> Best regards. >> >> Jean-Samuel. >> :-) >> >> >> >> 2012/3/14 Andrey Sviyazov <andreysviyaz at gmail.com> >> >>> Hi all! >>> >>> I am again about far-near problem. >>> >>> If we have heterodyne noise -135dBc/Hz at 600kHz offset (ADRF6601), then >>> for blocking signal at the same offset and at 200kHz RBW we get additional >>> noise level 135-53=72dBc relative to blocking signal level. >>> To keep "normal GSM900 BS" sensitivity -104dBm we must keep additional >>> noise as low as -107dBm, therefore blocking signal maximum level must less >>> then -107+73=-39dBm. >>> But in GSM-05.05 (sec 5.1) I saw blocking characteristics requirements >>> for normal BTS must be -26 dBm at 0.6-0.8 MHz offset and -16 dBm at 0.8-1.6 >>> MHz offset. >>> So, I do not know how and who can meet those requirements and I am >>> really hope that there are fundamental mistakes in my calculations. >>> Correct me please. >>> >>> Best regards, >>> Andrey Sviyazov. >>> >>> >>> >>> 16 января 2012 г. 19:22 пользователь Jean-Samuel Najnudel - BJT PARTNERS >>> SARL <jsn at bjtpartners.com> написал: >>> >>> Hi Alexander, >>>> >>>> These last days, I tried to find a solution for the selectivity >>>> improvement. >>>> >>>> I have 5 solutions to propose. 1st and 2nd are inboard solutions. 3rd, >>>> 4th and 5th uses an external board. Some seems to be much better than >>>> others. >>>> >>>> 1/ We could use an IF frequency above 375 MHz to be able to connect the >>>> IF signal dirtectly to the LMS, without any upconvertion back to RF >>>> frequency. This would save some components. >>>> We could use the ADRF6601 (PLL/VCO + mixer) and the TB0448A IF SAW >>>> filter. >>>> The ADRF6601 is single chip PLL/VCO and mixer. This would be quite >>>> convenient. >>>> The TB0448A is cheap (< 3 USD), narrow band (good selectivity) and 400 >>>> MHz center frequency (> 375 MHz LMS lower limit). >>>> >>>> Cost of this solution would be about 60 USD and selectivity would be >>>> really good. >>>> The main disadvantage of this solution is the filter would restrict the >>>> signal to a single GSM carrier. This would avoid us to get both GSM >>>> carriers on each LMS. We would not be able to get true diversity. We would >>>> only be able to get switched diversity. >>>> >>>> After the LNA, RF SAW filter and the RF switches, we can split the >>>> signal between the current RX path to LMS RX LNA 3 and a new alternate RX >>>> path (ADRF6601 => TB0448A => LMS RX LNA 1). >>>> Depending of our need for selectivity, we would be able to select 1 of >>>> these 2 RX path (direct RX path to LMS RX LNA 3 or IF filter RX path to LMS >>>> RX LNA1). >>>> >>>> This would allow to use the board either as a normal wideband SDR board >>>> or with a very selective filter. >>>> >>>> >>>> 2/ A very nice option would be to use a variant of the 1st solution >>>> with a wider bandwidth SAW IF filter. For example, if we use a 400 to 600 >>>> KHz bandwidth IF filter, we would also get a very good selectivity and we >>>> would also be able to sample both GSM carriers on each LMS. This would >>>> allow a good selectivity and full diversity. >>>> >>>> The problem is we would need a 400 to 600 KHz SAW IF filter, with good >>>> selectivity, reasonable price and an IF center frequency above 375 MHz. I >>>> was not able to find such a filter. >>>> >>>> >>>> 3/ As suggested a few days ago, we may use the external selectivity >>>> improvement board design I sent you. Instead of the Triquint 856378 IF SAW >>>> filter, we could use the TAISAW TB0448A narrow band filter. This TAISAW >>>> filter is really much cheaper than the Triquint. This would save a lot of >>>> budget. However, we would still need 4 mixer and 2 PLL/VCO for each LMS RX >>>> path. This external board would cost approximately 100 USD (excluding PCB >>>> and assembly). We would need 2 of these boards for each UmTRX board. This >>>> would make 200 USD per UmTRX. Including PCB and assembly, toatl cost would >>>> be around 300 USD. This is not compeltely unrealistic but it seems still >>>> quite expensive. >>>> >>>> >>>> 4/ Another solution would be to build a single carrier version of the >>>> 3rd solution design. We would need only 1 RF path (PLL/VCO + mixer) with >>>> only 1 narrow band filter per LMS RX path. This would not need any splitter >>>> or combiner. Design would be quite simple and cost would be about 2 times >>>> lower. However, as we will have only 1 carrier on each antenna, we would >>>> not be able to get diversity at all. >>>> >>>> This solution would finally not have many advantages compared to 1st >>>> solution. It would cost more and would not allow any kind of diversity. >>>> >>>> >>>> 5/ Last solution would be to build an external diversity improvement >>>> board, as 4th solution, but with a wider band IF SAW filter. >>>> >>>> We could use the following RF path: >>>> LNA => RF SAW filter => mixer => IF SAW filter => mixer => RF SAW >>>> filter. >>>> Dual mixer could be the ADL5802 connected to the ADF4350 PLL/VCO. >>>> >>>> We could use the TB0218A IF SAW filter. This filter is quite affordable >>>> (< 10 USD). Selectivity is good and bandwidth is wide enough to select 2 >>>> GSM carriers (separated by 400 KHz). >>>> >>>> Cost of such external diversity improvement board would be quite >>>> reasonable. >>>> This would be a very nice solution to select 2 GSM carriers. Connected >>>> to the UmTRX, this selectivity improvement board would allow to get both >>>> switched or true diversity. >>>> >>>> As TB0218A center frequency is 140 MHz, we would not be able to connect >>>> directly the IF signal to the LMS. We would need to up convert the signal >>>> back to the RF frequency. >>>> As IF down converted signal is upconverted back to the original RF >>>> frequency, it would be possible to use this selectivity improvement board >>>> with any kind of existing OpenBTS (UmTRX, USRP, SSRP...) or OpenBSC >>>> (Sysmocom BTS, IP.access nanoBTS...) hardware to improve the Rx >>>> selectivity. This would offer a wider potential market than an inboard >>>> solution. >>>> >>>> >>>> Considering all these solution, I believe 1st and 5th solutions seems >>>> to be the best choices. 2nd solution would also be really nice but I was >>>> not able to find the appropriate IF SAW filter. >>>> Please let me know your opinion regarding each of these two solutions. >>>> >>>> By the way, the TB0448A and TB0218A SAW filters looks really good but I >>>> am not 100% sure the GSM carrier spectrum distortion due to the pass band >>>> ripple of the SAW filter is acceptable. >>>> Center part of the GSM carrier (f +/- 100 KHz) is fine but side parts >>>> of the GSM carrier (bellow f - 100 KHz and above f + 100 KHz) may be cut a >>>> bit by the SAW filter. >>>> >>>> Could you also please check the TB0448A and TB0218A datasheets to >>>> double check if the usable bandwidth is wide enough ? Especially, do you >>>> think cutting a bit the side parts of the GSM carrier may cause problem ? >>>> >>>> Anyway, please let me know your point of view regarding these >>>> selectivity improvement solutions. >>>> >>>> Best regards. >>>> >>>> Jean-Samuel. >>>> :-) >>>> >>>> >>> >> > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/umtrx/attachments/20120316/554e4091/attachment.htm>