Dear Huacheng,
while it's hard to rule something like that out, it'd be surprising. Maybe you had a very
strong interferer that led to undesired intermodulation? Next time it happens, try to scan
through the overall spectrum (not only within your bandwidth of interest!) with a spectrum
analyzer, or drastically reduce the RF gain in your N310: if reducing the frontend gain
improves DC offset performance, chances are the mixer doesn't operate in the expected
regime due to external power.
Best regards,
Marcus
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On 13.12.21 15:53, Zeng, Huacheng wrote:
Hi Marcus,
I constantly observed the DC offset and harmonic peaks yesterday. But they simply
disappeared today. I am pretty sure I did not make any changes on hardware or software.
One possibility is that they were caused by a long time use or the temperature change
(room temperature < 25C).
I will report here if I can reproduce the problem. Thanks anyway!
Huacheng
On Sun, Dec 12, 2021 at 2:24 PM Marcus D. Leech <patchvonbr...@gmail.com> wrote:
On 2021-12-12 11:57, Zeng, Huacheng wrote:
Hello,
I am using N310 to observe its received signal in its four channels. I
observed
some unexpected DC offset and harmonics as shown in the attached figure. It
happened only at channels RF0 & RF2; the signal from channels RF1 & RF3
looks
normal. I disconnected the antennas but the DC and harmonics are still
there. And
they would not change if I change the center frequency, sampling rate, or
RF gain.
The GNU RADIO and UHD versions are below:
[INFO] [UHD] linux; GNU C++ version 7.5.0; Boost_106501;
UHD_3.15.0.HEAD-0-gaea0e2de
I also attached my python script code in case it would be useful for you to
identify the problem.
Any suggestions? Thank you in advance!
Hua
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Also, could you try explicitly specifying a subdev-spec of:
"A:0 A:1 B:0 B:1"
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