On 2021-09-05 11:28 a.m., zhou via USRP-users wrote:
Hi All,
I have a problem in using X310 USRP after upgrading UHD from 3.10 to
4.1.0. I am using it to capture NR5G radio signal in UL. After
analyzing the captured signal, the quality in the last subframe is
worse than the earlier subframes.
EVM =
[1.014, 1.08, 1.055, 1.053, 0.954, 1.043, 1.145, 1.112, 1.162, 1.072,
1.131, 1.125, 1.038, 1.08, 1.003, 1.1, 0.972, 0.941, 1.046, 0.917,
1.01, 1.023, 1.025, 0.982, 1.101, 1.044, 1.089, 0.987, 0.923, 1.022,
1.012, 1.009, 1.021, 1.037, 0.998, 1.112, 1.112, 0.981, 0.987, *2.785*]
When using UHD 3.10, I had no such problem.
If I deliberately capture one more subframe with UHD 4.1.0 but ignore
it when analyzing the signals, I will have good EVM.
Is this a bug in FPGA for UHD4.1.0 in X310?
Thanks for any input.
Hongwei
My guess is that there are just slight timing and/or group-delay
deifferences between the two FPGA releases, and your capture time is
just slightly too short
to account for that.
It is inevitable that going from a quite-old release to very much newer
(latest) release that there will be subtle things like group delay
differences between the
two FPGA implementations.
How do you decide when you are "done" capturing? How are you
capturing? Do you do your processing in real-time, or do you capture to
a file then
process the file.
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