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