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 :) Saw a nice lecture from the last conference by Matt Ettus: https://youtu.be/Qx8uFhumgGM?t=26826 Will try to follow that and see how it goes. On Tue, Nov 2, 2021 at 7:56 PM Dave Miller <dave.todd.mil...@gmail.com> wrote: > Hi Evgeny, > > 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" > > Regards, > Dave > > > > > ---------- Forwarded message --------- > From: Evgeny Hahamovich > Date: Thu, Oct 28, 2021 at 11:57 AM > Subject: MIMO with LimeSDR > To: <discuss-gnuradio@gnu.org> > > > Hi all, > > I am interested in checking the MIMO (well, actually it's SIMO for now) > work mode for my LimeSDR with GNURadio (v.3.8.3.1). 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 > -- Thank you, Evgeny Hahamovich Cell: +972-55-6633583 Biomedical Imaging and Sensing <http://lbis.net.technion.ac.il/>Laboratory <http://lbis.net.technion.ac.il/> Technion - Israel Institute of Technology
