On 05/03/2021 05:47 AM, Nieland, Michael wrote:
Dear all,
I am using two B210 USRP’s to generate and receive DQPSK Signals
around 1.53 GHz (two TX and two RX channels). The USRP’s use FW
Version 8.0 and FPGA Version 16.0 (Hardware Revision 4). I am having
some trouble properly changing the RX frequency at runtime using the
message interface. When the RX frequency is varied using a QT Gui
Range slider I encounter no issues. However, in my application I have
to use the message interface. In general, I assume that my pmt message
structure must be correct, since it works fine when the frequency is
only changed by a few MHz. Also other commands (like setting tx and
rx gains) work as expected. If, however, the frequency is requested to
be set to let’s say 2 GHz from 1.53 GHz, an overflow is indicated and
the respective USRP Channel completely stops streaming (does not
restart).
I tried using the “freq” command (both with indicating the channel and
without since it should not make a difference on the B210) and the
tune_request. I tried several different message structures but for
some reason it only works for the TX Usrp (When using the message port
of the TX Usrp to change frequency it is indicating some underflows
right when the frequency is changed and is then working fine without
any underflows or other issues).
To eliminate the error I am right now testing in an isolated FG with
only a USRP source and a Message Edit Box (FG is attached) and the
issue occurs here as well.
Any help would be appreciated and maybe someone was/is facing the same
issue?
Best regards
Michael
Have you tried using the "direct" interface for tuning--bypassing, for
now, the message infrastructure? Just use your rx_freq
variable directly in the UHD source block frequency input field? If
that also produces overruns during tuning, then the issue
is deeper inside than the message interface.
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