Re: [Openbts-discuss] openbts with external clock - can't camp

[Orkhan B. <orx...@gm...>]

Thanks for the reply Thomas

About antennas - I am using SBX daughterboard with 2 VERT900s on both TX/RX
and RX.

The rxgain was typically 10dB, but I also tested with 20dB.

The uhd version is 3.4.0 - UHD_003.004.000-299-g2033713d

Also, while reinstalling for using with external clock, is there any need
to change anything else other than including "--with-extref"?

On Sat, Mar 24, 2012 at 6:52 PM, Thomas Tsou <tt...@vt...> wrote:

> On Sat, Mar 24, 2012 at 12:18 PM, Orkhan Badirkhanli <orx...@gm...>
> wrote:
> > Hello list
> >
> > I am using USRP n210 to run openbts. I used to run it using the internal
> > clock of the device, the ppm value of which was roughly 3ppm based on the
> > results of kalibrate application.
> >
> > I was able to camp a handset from a short distance(about 2m) only, from
> > longer distances it was displaying openbts on the list on operators but
> was
> > not camping. I tried to change the power, but obviously that was not the
> > issue. My guess was that it was because of the clock.
>
> Distance based issues are almost always gain related. The more typical
> experience is the opposite of what you described where one side of the
> connection saturates. Clock issues won't have a significant effect
> over a 2m distance change. What are your antenna configuration and
> attenuation / rxgain values?
>
> > I connected a signal generator as an external clock and ran kalibrate
> again
> > and this time the ppm value was 0.025. I reinstalled openbts with
> external
> > clock option, but this time the phone was not camping from even short
> > distance.
>
> What release or git version of uhd do you have installed? The current
> code uses the uhd-3.3.0 clock setting interface that was deprecated in
> uhd-3.4.0, which was officially released yesterday. It shouldn't
> matter, but there have been few reports that kalibrate only worked
> after changing to the new interfaces.
>
> I can push a similar changeset sometime this weekend.
>
> > Let me note that the device was not locking to the external clock when I
> > connected to the front REF-IN input, it only did lock when I connected to
> > the second external clock input inside the USRP n210(by the way, I did
> > change that jumper from 1-2 to 2-3).
>
> Strange. From an OpenBTS standpoint, the actual clock setting is
> simply 'uhd::clock_config_t::REF_SMA'. The jumper should allow use of
> either input.
>
>  Thomas
>



-- 
Orkhan