Hi, everyone.I am doing the estimation angle of arrival by using USRP.
The problem I want to fix is the initial phase offset of each dboards.
From now on, I have searched some knowledge about this issue. But I can
not implement the concept.
those concept I got are below:
- Some kinds of dboard’s initial phase offset can remain constant after
re-tune by timed command (code)
http://files.ettus.com/manual/page_sync.html
- I saw some AOA finding hardware set using another usrp or dboard to
transmit a reference signal into the USRPs which are receivers connected
to antenna array elements.
https://decibel.ni.com/content/docs/DOC-25716
Because the dboards I use is not only one type(SBX), so I prefer to use
the reference signal to do calibration of dboard.
My simple hardware set is below:
Two usrp 2932 (with SBX)
One trimble GPSDO to provide 1PPS and 10MHz
I use GNUradio 3.7.5.1 , UHD_003.008.002-0-unknown
I receive a signal by Two usrps which is connected to ‘one antenna’.
Theoretically, when I plot the I Q data from two usrps, I will get same
waveform(phase). But I get the offset still and I find the offset is not
constant!!
summary of the problems I am suffering:
-
I do not know where and how to add those ‘timed commands’ which
taught in the USRP Hardware Driver and USRP Manual.
(I saw someone said that I can do nothing and the initial offset of SBX
will remain constant after retuning. But the result tell me it’s not
true.) -
Can anybody provide or teach me the code of phase calibration by
using another USRP ??? I saw some presentation but there is no source
code I can learn…
I try to use the two port (RX1 and RX2) to receive the signals in the
same time, but I failed.
I really do not understand how to set the gnuradio blocks to complete
these work.
any example could provide to me or anyone can help me??
(I think I know those concepts and knowledge but I can implement it in
hardware and software)
thx a lot !!