Hi Ralph, as usual, there can be a trick or two applied to that "data volume" problem: If you need two channels that are fairly far apart, i.e. close to the edges of what's sampled, just instruct UHD to digitally tune by half the master clock rate - you'll be doing a low/highpass transform on the signal, and then you can get them both in a smaller baseband bandwidth.
Cheers, Marcus On 08/31/2017 08:26 AM, Ralph A. Schmid, dk5ras via USRP-users wrote: > > And to add, the possible bandwidth is even 61.44 MHz with the B210. > The attenuation at the band edges gets a bit higher with this mode, > and it is not too clearly mentioned in the AD9361 specs, but I am > using the B210 with this setting and have no issues with it. This > clock appears being a tribute to LTE demands, based on the typical > 30.72 MHz from LTE. > > > > However 56 MHz are just fine for GSM bands with the typical 45 MHz > shift between uplink and downlink. Just handling the amount of data > may be a problem :) > > > > Ralph. > > > > *From:*USRP-users [mailto:usrp-users-boun...@lists.ettus.com] *On > Behalf Of *Marcus Müller via USRP-users > *Sent:* Wednesday, August 30, 2017 10:33 AM > *To:* usrp-users@lists.ettus.com > *Subject:* Re: [USRP-users] Capturing GSM downlink and uplink signal > with USRP B210 > > > > Dear Erik, > > in general: No, but in a specific Up/Downlink scenario, it might work. > > To explain: > > The B210 indeed has two RX chains, but they are both mixed with the > *same* LO. That means that the spectrum you get can only be within the > analog bandwidth around that LO at f_RF: > > spectral aspects > > This figure just shows a single receive channel with a digital tuning > offset of f_offset. You might imagine a second one, just with > -f_offset, i.e. to the left of f_RF. > > At the most, you could cover a piece of spectrum that is b_analog > wide. That b_analog is adjustable on the B210, but it's limited on the > upper end to 56 MHz. > > So, if the lowest channel of your Uplink and the highest channel of > your Downlink fit within 56 MHz, you're fine, and this is > theoretically possible (still have to choose sampling rates that work > for the 56 MHz analog bandwidth, and still have to have a USB3 > controller strong enough to not break down under heavy load if the > combined load of your two RX channels are rushing through it)! > > So: that's an "it depends, but in many cases, it might work"! > > Best regards, > Marcus > > On 30.08.2017 10:16, erik via USRP-users wrote: > > Hi List, > > I would like to capture GSM downlink and uplink signals with USRP > B210. > > I have done this previously with 2 units of USRP and connected via > MIMO cable. My question, is it possible to perform this activity > with USRP B210, which already have 2 RF channels and do i have to > add additional clock source or is it enough with USRP B210? > > Thanks and best regards, > > Erik > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com <mailto:USRP-users@lists.ettus.com> > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
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