[Discuss-gnuradio] timestamps inband

[Dimitris Symeonidis]

Hi list,

we're trying to use the inband FPGA image (inband_2rxhb_2tx.rbf)
trying to get the samples coming from two channels (for now, maybe
more later) on the same rev4 USRP aligned. Our ultimate goal is to do
beamforming with the USRP.

We have noticed that the distance between the timestamps of packets
from the two channels is linearly increasing, instead of being
fixed... Does anyone have any idea what could be at fault here?

We also noticed that the timestamp distance between packets of the
same channel is not fixed, as we would expect, but varying. If
sampling is synchronous, shouldn't the packets have a fixed distance
between them?

Do we even need timestamps, or are the samples aligned (interleaved)
anyway, even with the standard FPGA image? We don't care about
absolute time, just time (phase) difference between the two channels.

Thanks in advance, and sorry for the multiple questions in the same email

Dimitris Symeonidis
"If you think you're too small to make a difference, try sleeping with
a mosquito!" - Amnesty International