UmTRX

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189 discussions

Multicarrier OpenBTS on UmTRX
by Thomas Tsou 30 Oct '12

30 Oct '12

Hi all, I spent some time yesterday testing UmTRX with MCBTS. Aside from some trivial fixes (inverted sample rate), the code ran fine with no issues. The default bandwidth of the LPF was insufficient, so that was widened. I tested with 9 handsets between 3 and 7 carriers on a Core2 Duo (P7570) laptop. git://github.com/ttsou/openbts-multi-arfcn.git umtrx Configuration is through sqlite database, which is unchanged from mainline; just set the number of ARFCN (7 max) and C1 channels. Because of the bandwidth involved, be sure to increase the maximum buffer sizes for UHD. The uhd_usrp_probe utility will warn if the target size cannot be set. http://files.ettus.com/uhd_docs/manual/html/transport.html#linux-specific-n… Design ===== There are three resampling stages. 1. Outer resampler converts from the device rate to a multiple of the 400 kHz channel spacing. 2. Channelizer demultiplexes input stream to M channels 3. Inner resampler converts from 400 kHz to a multiple of the GSM symbol rate. UmTRX rates: Channelizer Rate Device Rate Decimation 1.6 Msps 1.625 Msps 8 3.2 Msps 3.250 Msps 4 Options ====== To broadcast dummy bursts on all carriers for spectrum testing, uncomment the following preprocessor declaration in radioParams.h. #define ENABLE_ALL_CHANS With dummy bursts on all carriers: http://filebox.vt.edu/users/ttsou/http/7carrier_umtrx.PNG Calibration ======== Calibration remains a concern. With single carrier, the carrier leakage and and IQ imbalance appear as in-band distortion. For MCBTS, OpenBTS offsets C0 on to the lowest carrier. This makes the carrier and image quite visible, as shown in the following uncalibrated capture. I checked with a swept tone to verify that this issue was not a result of baseband DSP. The USRP also shows similar effects. http://filebox.vt.edu/users/ttsou/http/carrier_image.PNG Any idea how much carrier and image suppression we should expect with calibration on UmTRXv2? Thomas

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UmTRXv2 Beta: Whats the maximum # of simultaneous callers
by SoftwareRadioGuy 30 Oct '12

30 Oct '12

Hello, I've read that the # of maximum callers is 15. Since there are "Beta" version coming out will these be able to handle 15 simultaneous callers too? SoftwareDefinesRadio

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Superb potential! Re: UmTRXv2 Beta: Whats the maximum # of simultaneous callers
by SoftwareRadioGuy 30 Oct '12

30 Oct '12

Alexander, Superb potential of the device you and the Fairwaves team are bringing to fruition. I also look forward to your future potential product, UmTRXv3 4G/LTE. I know its just something your team and you have thought about publically, alot of us would love to see such. Thank you for your responses. SoftwareDefinesRadio On Tue, Oct 30, 2012 at 5:07 AM, Alexander Chemeris < alexander.chemeris(a)gmail.com> wrote: > Hi, > > On Tue, Oct 30, 2012 at 12:36 PM, SoftwareRadioGuy > <softwaredefinesradio(a)gmail.com> wrote: > > I've read that the # of maximum callers is 15. > > > > Since there are "Beta" version coming out will these be able to handle 15 > > simultaneous callers too? > > A short answer is "yes, after a software update". > > A longer answer is that hardware supports dual-TRX operation, but > software support is not there yet. We might be able to fix software > before we ship beta units, but even if not - you will be able to get > the software update later. > Also keep in mind, that UmTRX should be able to run multi-ARFCN > OpenBTS and in this case it'll be able to handle much more calls. We > haven't tested this mode of operation extensively yet, but > theoretically we might be able to support 14ARFCNs (2x7ARFCN) which > equals to (14*8-1)=111 calls. At this scale you're most likely limited > by computing power of your PC rather then UmTRX hardware. Whether we > could get UmTRX in Multi-ARFCN mode through certification or not is > still a question, but it should be fine for lab testing. > > > -- > Regards, > Alexander Chemeris. > CEO, Fairwaves LLC / ООО УмРадио > http://fairwaves.ru >

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Re: Question regarding UmTRXv2 for early adopters should be ready in just few weeks
by SoftwareRadioGuy 30 Oct '12

30 Oct '12

> > Alexander, > > >> >> Does this mean people whom purchase the UmTRXv2 Samples will be able to >> >> obtain the Schematics/Gerber Files ? >> > >> > Yes. >> > Schematics are already published, btw: >> > https://github.com/chemeris/umtrx-schematics >> > > >> Just curious - what do you need gerbers for? Want to make some >> improvements? >> > > Prospectively, but if that wasn't in your plans, no problems. > > I support your efforts! > > > -- > Regards, > Alexander Chemeris. > CEO, Fairwaves LLC / ООО УмРадио > http://fairwaves.ru > > Sincerely, > > > SoftwareDefinesRadio > >> >

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Question regarding UmTRXv2 for early adopters should be ready in just few weeks
by SoftwareRadioGuy 30 Oct '12

30 Oct '12

Alexander, " UmTRXv2 samples for early adopters should be ready in just few weeks " per here: http://lists.osmocom.org/pipermail/umtrx/2012-October/000252.html And this page states: " Note: PCB layout will be published here when we start selling UmTRX boards. Prior to that it's available per request to our partners. " https://github.com/chemeris/umtrx-schematics Does this mean people whom purchase the UmTRXv2 Samples will be able to obtain the Schematics/Gerber Files ? Sincerely, SoftwareDefinedRadio

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UmTRX housing for labs usage.
by Andrey Sviyazov 29 Oct '12

29 Oct '12

Hi all. I spend this day in tries to find enclosure for UmTRX which are suggested to use in labs. I decided to return to my idea about fanless 5.25" tray form factor. I think they must look good, low cost and popular. It's all because mass production for competitive market. Examples: http://market.yandex.ru/model.xml?modelid=4957720&hid=818965 http://market.yandex.ru/model-spec.xml?modelid=2435964&hid=818965 http://market.yandex.ru/model.xml?modelid=1587657&hid=818965 http://www.amazon.de/gp/product/B004BUBND8/ref=olp_product_details?ie=UTF8&… http://www.amazon.de/Silentmaxx-HD-D%C3%A4mmung-Rev-2-0/dp/B001CKY4Y0/ref=p… http://www.amazon.de/Scythe-SCH-1000-Himuro-Festplattenk%C3%BChler/dp/B0017… And one question: Does anybody really uses USRP in closed enclosure? Best regards, Andrey Sviyazov.

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Re: UmTRX Digest, Vol 4, Issue 35
by Darby 29 Oct '12

29 Oct '12

1. Power supply, 12V-18V DC, >=20W. I think it's easier to find a PSU with a standard round DC connector, like this one and thus we need a converter cable to our Molex power connector. http://domino2.kycon.com/catalog_PDF/KLDX_SMT2.pdf Not knowing center pin polarity or exact center pin size, it seems as though digikey (http://www.digikey.com/product-search/en/power-supplies-external-internal-o…) has 348 that are 12-18v output, 10-20w, and have connectors that are 2.1mm ID to 2.5mm ID On a side note, for power -Something that could come in useful since its got ethernet, PoE? 2. Enclosure. We'd love to have a nice table-top enclosure for UmTRX, but it requires a significant effort to source, design and assemble. If anyone has some preexisting case designs, there's always protocase (protocase.com) or Rapid sheet metal (http://www.rapidsheetmetal.com/parts/enclosures.aspx) -Im sure theres plenty of other sheetmetal fabshops that will do custom work though, If youre wanting to use something a bit more generic -Theres enclosurehub.com

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UmTRX power adaptor
by Alexander Chemeris 27 Oct '12

27 Oct '12

Hi all, UmTRXv2 samples for early adopters should be ready in just few weeks and we're looking at what to put an a package. Below is a preliminary list of items which I think we should include. Please comment on the list and suggest particular items: 1. Power supply, 12V-18V DC, >=20W. I think it's easier to find a PSU with a standard round DC connector, like this one and thus we need a converter cable to our Molex power connector. http://domino2.kycon.com/catalog_PDF/KLDX_SMT2.pdf 2. Converter cable from the Molex power connector to a standard round DC connector. 3. U.FL-to-SMA-F pigtail cable. 4. Two small antennas - omni or patch. One for Tx and one for Rx. Below is a list of items which are non-essential and which we unlikely to include in the package for this batch. We do no have them ready yet and we don't want to delay shipping. We focus our effort on polishing UmTRX and UmSEL performance and software development which we see as a more important tasks at this moment. 1. Duplexer. Without a power amplifier UmTRXv2 is pretty low-power (50-100mW) and thus it works good enough without a duplexer in a normal environment. For our testing we use two small antennas - one for Rx and one for Tx without any issues. 2. Enclosure. We'd love to have a nice table-top enclosure for UmTRX, but it requires a significant effort to source, design and assemble. 3. UmSEL. It's not clear whether we will have UmSEL production setup in time. Software to control UmSEL is yet to be developed as well. Since it's only an improvement frontend, I don't think we should include it into the basic package. If you want to help us make those items faster - by all means feel free to offer your help! :) * If you provide a valuable contribution, you'll get the item you're contributed to for free. * If you provide significant contributions on a regular basis, you'll get all our future hardware versions for free and recognition on the web-site. -- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru

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Storing calibration values in EEPROM
by Alexander Chemeris 26 Oct '12

26 Oct '12

Hi all, I've pushed an update to git to store some LMS6002D calibration values in UmTRX's EEPROM. The idea is to perform calibration once and do not worry about it anymore no matter what PC you connect UmTRX to. Intro ==== Right now we have the following values which could be stored in EEPROM: * tx-vga1-dc-i - DC offset calibration value for LMS6002D Tx I channel * tx-vga1-dc-q - DC offset calibration value for LMS6002D Tx I channel * tcxo-dac - TCXO calibration value Now, when the framework for UmTRX EEPROM is in place, we could store more values there as we see the need. E.g. we may want to store Rx DC offset calibration values or power limits of this exact units to be used by OpenBTS. The only limitation here is the size of the EEPROM. EEPROM is only 256 bytes large and some of them are already used, so we have about 200 bytes to use. With the strong dependency of calibration values on temperature and frequency, we might need a two-dimensional array for each value. In this case we may want to move those calibration values to flash instead of EEPROM. This would need some more work and thus is in our wish-list for now. Writing values =========== You could write values mentioned above to EEPROM as any other EEPROM value: ./host/build/utils/usrp_burn_mb_eeprom --key <name> --val <dec_val> (from the root of your UHD source tree) Reading values ============= You could read individual values from EEPROM as any other EEPROM value: ./host/build/utils/usrp_burn_mb_eeprom --key <name> --val <dec_val> (from the root of your UHD source tree) Or you could use `uhd_usrp_probe` to see them all at once at the top-level section: _____________________________________________________ / | Device: UmTRX Device | _____________________________________________________ | / | | Mboard: UMTRX-REV0 | | hardware: 64000 | | mac-addr: 00:50:c2:85:3f:ff | | ip-addr: 192.168.10.4 | | gpsdo: none | | serial: 1 | | tx-vga1-dc-i: 114 | | tx-vga1-dc-q: 138 | | tcxo-dac: 2022 | | | | Time sources: none, external, _external_, mimo | | Clock sources: internal, external, mimo | | Sensors: ref_locked | | _____________________________________________________ | | / | | | RX DSP: 0 | | | Freq range: -6.500 to 6.500 Mhz | | _____________________________________________________ | | / | | | RX DSP: 1 | | | Freq range: -6.500 to 6.500 Mhz | | _____________________________________________________ | | / | | | RX Dboard: A | | | ID: LMS RX (0xfa09) | | | Serial: 1 | | | _____________________________________________________ | | | / | | | | RX Subdev: 0 | | | | Name: LMS RX (0xfa09) - 0 | | | | Antennas: RX0, RX1, RX2, RX3, CAL | | | | Sensors: | | | | Freq range: 232.500 to 3720.000 Mhz | | | | Gain range VGA2: 0.0 to 30.0 step 3.0 dB | | | | Connection Type: IQ | | | | Uses LO offset: No | | | _____________________________________________________ | | | / | | | | RX Codec: A | | | | Name: LMS_RX | | | | Gain Elements: None | | _____________________________________________________ | | / | | | TX DSP: 0 | | | Freq range: -32.500 to 32.500 Mhz | | _____________________________________________________ | | / | | | TX Dboard: A | | | ID: LMS TX (0xfa07) | | | Serial: 1 | | | _____________________________________________________ | | | / | | | | TX Subdev: 0 | | | | Name: LMS TX (0xfa07) - 0 | | | | Antennas: TX0, TX1, TX2, CAL | | | | Sensors: | | | | Freq range: 232.500 to 3720.000 Mhz | | | | Gain range VGA: -35.0 to 21.0 step 1.0 dB | | | | Connection Type: IQ | | | | Uses LO offset: No | | | _____________________________________________________ | | | / | | | | TX Codec: A | | | | Name: LMS_TX | | | | Gain Elements: None PS I've added this text to the wiki for future reference: https://code.google.com/p/umtrx/wiki/UmTRXCalibration -- Regards, Alexander Chemeris. CEO, Fairwaves LLC / ООО УмРадио http://fairwaves.ru

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UmSEL Pdet and Vcnt
by Andrey Sviyazov 22 Oct '12

22 Oct '12

Hi Jean-Samuel. Pdet1&2 dedicated for Output power detectors and Vcnt1&2 for test points voltage control. For example, PA +24V and feeder supply voltage 28..36V of DC-DC converter (in case of positive type, i.e. minus connected to chassis). Each input of ADS1015 contains divider of 1:10, so it makes possible to measure up to 41V with 0.01V resolution. Best regards, Andrey Sviyazov. 2012/10/22 Jean-Samuel Najnudel - BJT PARTNERS SARL <jsn(a)bjtpartners.com> > Hi Andrey, > > I can see in the UmSEL 4 channels ADC. > > What do you plan to do with this ? > What is Pdet and Vcnt ? > > I ask you this because it would be really nice to use 2 of these ADC > channels to monitor each of the 2 PA RF Pout. > What would you think about this ? > > Best regards. > > Jean-Samuel. > :-) > >

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