Hi Thomas, This is a known hardware issue with earlier revisions of the B200mini and has been fixed on newer versions. Please contact supp...@ettus.com and they can help get the boards reworked.
Regards, Michael On Sun, Feb 25, 2018 at 6:54 AM, Thomas Teisberg via USRP-users < usrp-users@lists.ettus.com> wrote: > I'm sorry, which thread are you referring to? > > I have tried implementing the changes in the thread I originally linked to > and it doesn't seem to have made any difference. > > Best, > Thomas > > On Feb 25, 2018 4:52 AM, "Steven Knudsen" <ee.k...@gmail.com> wrote: > >> Hi, >> >> This is a known problem with the B20xmini. Have a look at this thread and >> then follow it up. >> >> You are right, you are seeing caps charge and discharge, basically. >> >> Since I made the changes myself on my units, I am not sure where things >> were left with Ettus and their policy for fixing the problem. But I can say >> that once you make the changes, the transients are gone and the minis work >> really well. >> >> regards, >> >> steven >> >> >> On Sat, Feb 24, 2018 at 3:25 PM, Thomas Teisberg via USRP-users < >> usrp-users@lists.ettus.com> wrote: >> >>> I'm working on a radar project that requires sending a series of short >>> pulses. Looking at the pulses on a scope, I'm seeing large voltage spikes >>> at the beginning and the end of each transmission. >>> >>> As shown in the attached screenshot, before the transmission starts, >>> there is a 90 mV spike lasting about 10 us. After the transmission, there's >>> a -25 mV spike lasting about 20 us. >>> >>> The setup for this is simply a USRP B205mini-i connected to a 50 ohm >>> input on a scope through a 30 dB attenuator. The signal is at 435 MHz with >>> the scope sampling at 20 Gsps. >>> >>> Our initial thought was that we must be seeing some effects of some of >>> the RF frontend components turning on and off. I found this previous >>> mailing list post and tried the suggested fix in b200_impl.cpp but nothing >>> changed: >>> >>> http://lists.ettus.com/pipermail/usrp-users_lists.ettus.com/ >>> 2015-January/012269.html >>> >>> Any ideas why we might be seeing these spikes or what we could do about >>> it? Does the fix suggested in the above mailing list post still apply to >>> the current codebase? >>> >>> Thanks, >>> Thomas >>> >>> _______________________________________________ >>> USRP-users mailing list >>> USRP-users@lists.ettus.com >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >>> >>> >> >> >> -- >> K. Steven Knudsen, Ph.D., P.Eng. >> > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >
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