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From: | Luis Felipe Albarracin Sanchez |
Subject: | [Discuss-gnuradio] Constellations, EVM and SNR Questions |
Date: | Thu, 7 Jun 2018 12:24:12 +0200 |
Hello Everyone,I am trying to run a model with different modulations, and to see different measurement values ( Constellation Diagram, EVM, and SNR). i have done the following but it does not seem to work:1- I try plotting a DQPSK modulation with "QT GUI Constallation Sink" (directly form the modulating block and it shows a graph like this:As you can see i have dots that are not where they are supposed to be (in every corner), to try to solve this i placed a "sink file" block from the out of the "modulating block", and i tried to plotted in matlab to see if i had a better image. Unfortunately it went worse. In matlab i read the bin file it showed a row with many numbers (none of them bigger than 255) so i assumed it came formatted every 8 bits .Fist thing i separated what i have read is the real and the complex part, and i tried to plotted, and it did not work....show many points none of them in the corners where they are supposed to be. After that i thought maybe the Most Significant Bit is the "sign", so i adjusted the program in matlab and ran the plot, but it also did not work.Below the plot i get:I wanted this so i can design a program on Matlab to calculate EVM for future measurements, nevertheless i wanted to measure EVM on GNURadio, and also i am looking for a way to measure SNR with different modulations.Given this, i would appreciate your help with the following:1- How can i have a graph of the constellation for different modulations in GNURadio, that is accurate.2- How can i export data file form GNURadio (the output of a modulator block) and plot the costellation in matlab properly?3- Is there any git repository where i can find blocks for EVM and SNR for different modulations, if not is there a way or known resources, or flowgraphs to do SNR measurements and EVM measurements?Once again thanks for all the help.Kind regards.
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