Thanks for the suggestion about the noise source -- that's what I would normally do. Unfortunately I haven't actually purchased the hardware yet -- I was hoping to clarify this issue before raising a purchase order.
Perhaps I should follow this up with one of the application engineers at NI? They might have access to an X310+UBX-160 system that they can use to answer my question directly. Thanks again for your help in this matter. Regards, Brendan. On Wed, 19 Feb 2025 at 09:55, Marcus D. Leech <patchvonbr...@gmail.com> wrote: > On 18/02/2025 18:45, Brendan Horsfield wrote: > > Yes, I assumed that was the case. However, it is not clear from the X300 > documentation how sharp those filters are. Can you tell me how wide the > transition band is at the lower sample rates? > > To give you some context, I would like to use an X300 (or X310) with a > UBX-160 daughterboard to digitise the entire 2.4 GHz Wi-Fi band, which is > 83.5 MHz wide. Ideally I would like to use a sample rate of 100 Msps to > minimise the data rate between the USRP and the host PC. However, before I > do this I need to be certain that the usable bandwidth at this sample rate > will be greater than 83.5 MHz. Is this information documented somewhere? > > > It somewhat depends on the decimation. If the decimation has a factor of > two or 4, the edge roll-off is fairly sharp. Otherwise, > there's a half-band filter in-place that causes a less-desirable > pass-band. > > But I don't know, precisely, what the transition band is in the "nicer" > filter shapes. > > > If you have an X310+UBX-160, you can always just use a noise source, and > measure it yourself to see if it's appropriate for > your application. > > > > > On Tue, 18 Feb 2025 at 23:11, Marcus D Leech <patchvonbr...@gmail.com> > wrote: > >> There will always be some edge roll off. Decimation includes filtering >> and those filters cannot be infinitely steep. >> Sent from my iPhone >> >> > On Feb 18, 2025, at 2:12 AM, Brendan Horsfield < >> brendan.horsfi...@vectalabs.com> wrote: >> > >> > >> > Hi All, >> > >> > I have a question about the usable bandwidth of the X300 USRP / UBX-160 >> daughterboard combo at sampling rates below 200 Msps: >> > >> > As I understand it, the UBX-160 receiver has an analog (hardware) >> filter before the ADC that limits the usable bandwidth to 160 MHz, while >> the ADC runs at 200 Msps. Therefore the usable bandwidth is around 80% of >> the sample rate. >> > >> > My question is: What is the usable bandwidth at lower sampling rates? >> Does the 80% factor always apply? >> > >> > For example, if I set the decimation factor to 4, so that my sampling >> rate is 50 Msps, does this mean that the usable bandwidth will be 40 MHz? >> > >> > Thanks & Regards, >> > Brendan. >> > >> > _______________________________________________ >> > 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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