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Re: MIMO with LimeSDR
Re: MIMO with LimeSDR
Wed, 3 Nov 2021 16:24:04 +0200
Thanks Dave, read your previous post, indeed this is something similar to what I did.
Eventually I found the problem... I am used to LimeSDR having an automatic channel selection (L/W/H), and it appears that for channel B, you actually need to select one on your own :) After doing so, it works well!
Now I just need to figure out what to do with those two parallel streams :)
Will try to follow that and see how it goes.
A few months ago, I had I believe a similar situation with the LimeSDR-mini you describe below and show in your attached spectrum plots. Although not a MIMO configuration.
For me the solution was to not use the gnu radio in-tree modulation blocks in gnuradio version 3.8 with the LimeSDR sink block. I used my own modulator blocks for BPSK and later QPSK with the LimeSDR block. I sent a square wave pulse shape baseband signal to the input of the LimeSDR-mini.
The full discussion and solution for this work-around with flowgraphs and spectrum plots is on a Lime Myriad RF site thread in August that I established to get some input from the Lime Microsystems folks: "LimeSDR-Mini GR-3.8 Block Transmit Distortion"
---------- Forwarded message ---------
From: Evgeny Hahamovich
Date: Thu, Oct 28, 2021 at 11:57 AM
Subject: MIMO with LimeSDR
I am interested in checking the MIMO (well, actually it's SIMO for now) work mode for my LimeSDR with GNURadio (v.18.104.22.168). Getting into the MIMO mode was simple by setting RxChannel = A+B, but I got stuck just after this...
In the attached screenshots you can see the spectrum and constellations I got for QPSK. As you can see, one of the channels offers terrible performance :( Have you encountered something similar? This is strange to me, I didn't expect such a major difference between the 2 channels performance. Maybe I'm doing something wrong...
Also, can you advise on some blocks I can use for 2 antenas detection to improve performance or point me to some documentation or examples for using this mode?
Thank you,Evgeny Hahamovich
Technion - Israel Institute of Technology