On 2022-02-25 11:26, Zentarra, Michael wrote:
Hello everyone,
I was experimenting with two USRPs and encountered something I could
not explain. The setup is: HostA -> B210 -> Cable+Attenuator -> N310
-> HostB. GNURadio on the TX side is simply playing a signal via the
signal source block into the UHD USRP Sink. On the RX side the USRP
Source block is saving the signal through a head block into a file
sink. The received signal seems to contain sudden, periodic jumps as
can be seen in the picture below. For the attached picture the raw I
and Q signal is plotted. The jumps happen at different tested sample
rates, frequencies and gains on both sides. In the depicted example
the signal source block sent a constant with amplitude one. Center
frequency was set to 2,48 GHz with sample rates on both sides at 25,6
MHz. One can see the center frequency offset as expected but the
signal is sometimes jumping in 2 adjacent samples which indicates to
me that the receiver is adjusting something. This effect can also be
seen at other sent waveforms.
Does somebody know what causes such a behavior? Thank you in advance!
Kind regards
Michael
Try backing off the baseband amplitude a little bit. Also, if you're
sending a constant, that may cause the DC removal to "kick in".
Are you getting any "U" on the TX side or "O" on the RX side?