Hi John,

yes we are using the internal clock. It is just a bit weird that the exact same setup worked in the past. We then had the SDR deployed in another project and now wanted to try the setup again and it stopped working because of the shift.

But if it is technically within spec and we can't really do anything to fix this, I guess we just need a new SDR

On 6/12/26 10:42, Rognskog, John-Harry wrote:
Hi,
I assume you are using internal clock? 5kHz is within its spec (barely). My 
units vary in that range, although not as much individually.
Kind regards,
John

-----Original Message-----
From: Christian Zäske via USRP-users <[email protected]>
Sent: Friday, June 12, 2026 10:35 AM
To: usrp-users <[email protected]>
Subject: [USRP-users] B200 frequency shifted

Hello,

(Sorry if this is a duplicate, I think there went something wrong with my last 
email to the mailing list)

In the past, we used a B200 and srsRAN to build our own LTE cell, which always 
worked flawlessly. After some time, we wanted to build this setup again but we 
ran into an issue: The phone never found the cell.

After looking into the problem I noticed, that the output frequency of the B200 
is shifted around +5 kHz at around 2.6 GHz (Verified it with another SDR). Too 
much for the phone to get the signal properly. When I manually adjust the 
frequency in srsRAN to compensate for the 5 kHz shift, the phone immediately 
detects the cell.

At lower frequencies, the shift also gets lower.

Is there something we can do to revive the B200?  Because this exact setup 
worked in the past, I think something happened to the b200 that causes this 
shift.

Thanks in advance,
Christian

--
Christian Zäske
IT-Security Consultant
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