On 06/10/2021 04:50 AM, Skyvalakis
Gnu Radio does NOT emit code that wraps the tuning requests in timed
commands, so the synthesizers won't be properly
I set up the following flowchart:
Multi_usrp_source -----> complex_to_real -------> WX GUI
I repeated the phase identical test tone experiment multiple
times and I could clearly see that the phase offset between the
2 channels was different almost every time.
Phase offsets were ranging from almost 0 degrees up to 90
tuned for phase synchronization. ALSO the WX GUI Scope sink had
(as I recall) a bug that caused things to appear out
of phase even if they weren't. You should probably use the QT GUI
time sink instead--what version of GR are you using?
The WX GUI widgets have been deprecated for several years now, and
don't even appear in later versions of GR.
You'd have to modify the generated code to have it wrap the tuning
requests in timed commands.
Sent from my iPhone
Οk, I know the way of the atan2 method
you are proposing. I will try it tomorrow when I will
have access to the equipment again.
When you said injecting a phase
identical test tone earlier you meant, driving the
signal from the generator to the RX2 port of each one
of the SBX daughterboards (using a splitter), with equal
length cables and then checking the phase offset between
the 2 channels?
Exactly this, yes. You want to measure the phase offset that
is dominated by the receivers and not external path length
Your generated tone should be OK as long as the
path lengths are the same during phase calibration.
Measuring mutual phase offset can be done in a
number of ways like taking the atan2 of the two
channels and averaging.
Sent from my iPhone
You assumed correctly. I am doing this in
a single multi_usrp object, so it is ok. I
will also remove that sleep command.
I don't know how I can measure
the phase difference between the two RX
channels. In my DoA experiment I am just
transmitting a tone @ 868MHz from an RF
generator and I'm receiving it from the 2 RX
Also could you elaborate more
on the last thing you mentioned, the one
about the phase identical test tone....