Hi Thomas,

I applied the change suggested by you to enable 10 Mhz external clock.
I see a strange behavior now when measuring frequency offset using Kalibrate.
Below are the observations-

Board used- USRP2, Transmitting frequency = 945.2Mhz (GSM 900 band, ARFCN 51)

When Internal clock is configured, Frequency offset = +1.873Khz
When external clock is configured and switched on, Frequency offset = +2.721Khz
When external clock is configured and switched off, Frequency offset = -36.78Khz

Do you have any idea whats going on here ??

Thanks,

--
Abhinav

On Mon, Mar 21, 2011 at 9:56 AM, Thomas Tsou <ttsou@vt.edu> wrote:
On Mon, Mar 21, 2011 at 12:38 PM, abhinav anand <a.abhinav100@gmail.com> wrote:
> Hi Users,
>
> Is there any other code change required in OpenBTS for using external 10Mhz
> clock
> on USRP2 except the one in public-trunk/Transceiver/UHDDevice.cpp
>
> //Set the reference variable on line 44 to true.
> const bool enableExternalRef = true;

Nope. Just rebuild the transceiver and you're done.

http://gnuradio.org/redmine/wiki/gnuradio/OpenBTSUSRP2

It would be preferable to enable this at runtime, but that involves
changes outside of the transceiver code.

 Thomas