[USRP-users] [Openbts-discuss] new uhd breaks uplink?

Ian Buckley ianb at ionconcepts.com
Fri Apr 10 11:04:37 EDT 2015

A lot of big changes and bug fixes just propagated to the B2x0 public repo.
They include the long awaited digital filter upgrades. In the case of OpenBTS that is probably disruptive because it increases the group delay of the filter chains in the DDC and DUC significantly, so the uplink is probably not targeting timeslots accurately after the update. My (limited) understanding of OpenBTS is that it simply uses a hardcoded value currently to account for this delay. So that value is going to need an update, perhaps conditional on the FPGA compat number (>= 5). I'll get you a better answer later today.

On Apr 10, 2015, at 2:25 AM, "Ralph A. Schmid, dk5ras via USRP-users" <usrp-users at lists.ettus.com> wrote:

> I forward this to find out if I am the only one with this issue...
>> -----Original Message-----
>> From: Ralph A. Schmid, dk5ras [mailto:ralph at schmid.xxx]
>> Sent: Friday, April 10, 2015 8:21 AM
>> To: 'OpenBTS Discuss'
>> Subject: [Openbts-discuss] new uhd breaks uplink?
>> Hi,
>> Yesterday I updated uhd and the FPGA image for my B210, recompiled
>> OpenBTS, and suddenly the uplink did not work any more. Downlink was
>> fine, but no mobiles were able to register. As I needed a quick solution I
>> simply restored the backup of the VM, I will test this during the weekend
>> somehow more structured.
>> OPenBTS is latest release, uhd is compiled from sources, and I do a git
> pull /
>> make / install for uhd every few days, usually with no issues. OS is
> Kubuntu
>> 14.04 64bit.
>> Anybody else with such observations?
>> Ralph.
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