I have removed OpenBTS and USRP drivers and reinstalled with same results. On the USRP the 'E' LED is active which indicates a reference lock. When I ran kalibrate with the -x option this comes off and ./kal -s GSM900 finds nothing. Is there any additional info I can provide to assist with troubleshooting this problem?
 
> From: alexander.chemeris@gmail.com
> Date: Thu, 23 Feb 2012 17:39:34 +0400
> Subject: Re: [Openbts-discuss] Network does not appear in list
> To: ttsou@vt.edu
> CC: sammy_gy@hotmail.com; openbts-discuss@lists.sourceforge.net
>
> Thomas,
>
> On Thu, Feb 23, 2012 at 11:05, Thomas Tsou <ttsou@vt.edu> wrote:
> > On Wed, Feb 22, 2012 at 6:18 AM, Samuel Liverpool <sammy_gy@hotmail.com> wrote:
> >> Hi Alex,
> >>
> >> No I am not sure that it is being used by the USRP, but I did follow the
> >> instructions to enable it and therefore assumed that it is working. I also
> >> see a reference to it in kal. Here is the output from kal -s GSM900
> >
> > Let me say first that there was a bug in Kal that would prevent
> > auto-configuration of the GPSDO. It should  have worked fine if you
> > explicitly specified the external reference.
> >
> > https://github.com/ttsou/kalibrate-uhd/commit/3809ed65
> >
> > That said, the GPSDO should configure itself automatically in OpenBTS
> > and kal. However, you can explicitly specify the 'external' reference
> > in either case. External means the internal on-board reference is
> > disabled and the front panel connection _or_ GPSDO is used - which one
> > is determined by the jumper setting.
> >
> > In kal you can specify the reference on the command line. With OpenBTS
> > there is the "--with-extref" option at build time.
>
> Hum. Should we probably make it a runtime configuration option?
>
> >> linux; GNU C++ version 4.6.1; Boost_104601; UHD_003.004.000-122b947
> >>
> >> -- Opening a USRP2/N-Series device...
> >> -- Current recv frame size: 1472 bytes
> >> -- Current send frame size: 1472 bytes
> >> -- Found a Jackson Labs GPS
> >> -- Setting references to the internal GPSDO
> >> -- Initializing time to the internal GPSDO
> >
> > It is possible that kal started with the GPSDO and then proceeded to
> > disable it, which would be very confusing. Sorry about that.
> >
> >> UHD Warning:
> >> The hardware does not support the requested RX sample rate:
> >> Target sample rate: 0.270833 MSps
> >> Actual sample rate: 0.271739 MSps
>
> I wonder, is automatically Kal doing resampling with USRP2?
>
>
> --
> Regards,
> Alexander Chemeris.