Hi Marcus, Thanks, I was actually looking for a simplified block diagram, more than the schematics.
As per the get_rx_bandwidth. I checked, and it is 56MHz. I was guessing that this was more or less the config (my sampling frequency is actually 4MHz). Mainly because after sending the email this morning I checked some MHz away from my working freq (but still inside of ±16MHz) and the RFI was actually there and coming into my processing chain via subsampling. Hence, it seems it is not the USRP, there is an actual RFI at the end of the day coming into the USRP RF input. I may reduce the bandwidth, though. Thanks! Fran El mar, 26 dic 2023 a las 17:14, Marcus D. Leech (<patchvonbr...@gmail.com>) escribió: > On 26/12/2023 06:43, Francisco Gallardo lópez wrote: > > Hi all, > > I am seeing a quite strange pattern in an USRP B210, and I am trying to > figure out what it is. > > Right now this is more like an academic investigation, as this is not > causing malfunctions, but it got my attention. > > So, from time to time I am seeing a tone (20dB above noise) appearing just > in the middle of the band, to be precise ±2KHz around the central frequency > that I configured in the USRP. > > I was not paying attention at all, until I noticed that it appears every > day seven times a day, and always (more or less) at the same times. Hence, > this is not random. > > Gut feeling is that this is caused by some sort of signal induced into the > cables or locally radiated interference, not intended, of course. > > I was trying to further investigate, and for that I was trying to get a > detail blocks diagram of the B210, as I saw the following information in > the B210 website: "If you, however, happen to have a very strong > interferer within half the master clock rate of your RX LO frequency, you > might want to reduce this analog bandwidth. You can do so by calling > uhd::usrp::multi_usrp::set_rx_bandwidth(bw)." B200/B210/B200mini/B205mini > - Ettus Knowledge Base > <https://kb.ettus.com/B200/B210/B200mini/B205mini#FAQ> > > Now the thing is, I realized I don't really know what the internal > settings of the USRP are, also in terms of the Analog Devices AD9363. I > know that the clock rate is 32 MHz, but from there I don't clearly know > what is the LO frequency that the USRP set. > > Also, I would like to know the setting that the USRP is using for the > Analog bandwidth. > > In short, I would like to: > > a) Get a diagram like this one, but for the detailed case of B210. Is > there something like this? (File:2920 simplified system diagram.gif - > Ettus Knowledge Base > <https://kb.ettus.com/File:2920_simplified_system_diagram.gif>) > b) Know what is the LO freq that the USRP is setting (I assumed based on > the 32MHz clock rate) > c) Know where I can get the information on the setting the USRP is putting > for the analog bandwidth filter. > > Thanks! > Fran > > > > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com > > Francisco: > > There's the schematics here: > > https://files.ettus.com/schematics/b200/ > > Nearly all SDRs use direct-conversion, which means the LO is the same as > the desired RF frequency. The B2xx series works like this. > > Bandwidth can be set with a set_rx_bandwidth call, formally described here: > > > https://files.ettus.com/manual/classuhd_1_1usrp_1_1multi__usrp.html#a4e026819f286e69c48c2e1956d95c6fb > > Normally, UHD (the driver) will set the analog bandwidth to something > "appropriate" given your sample rate. > > If you change to a slightly different frequency, does this occasional RFI > stay at the same frequency? > > If you lower the RF gain, does it go away? > > > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >
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