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From: | Γιώργος Γιώργος |
Subject: | Απ: Issue with USRP signal reception when stream is produced by a Vector Source |
Date: | Wed, 9 Jun 2021 07:17:03 +0000 |
Hello Marcus,
Thank you very much for the swift answer. You're quite right, I should have noticed that. I will adjust accordingly and report back to update/close the thread.
Best regards,
George
Από: Discuss-gnuradio <discuss-gnuradio-bounces+zulkir=hotmail.gr@gnu.org> εκ μέρους του Marcus Müller <mmueller@gnuradio.org>
Στάλθηκε: Τρίτη, 8 Ιουνίου 2021 8:07 μμ Προς: discuss-gnuradio@gnu.org <discuss-gnuradio@gnu.org> Θέμα: Re: Issue with USRP signal reception when stream is produced by a Vector Source Just from very quickly over your attached images:
Your receiver is clipping, you can see that: the receive waveform should never even touch "1". You need to substantially reduce gain, potentially both in your receiver and transmitter. Best regards, Marcus On 08.06.21 16:32, Γιώργος Γιώργος wrote: > Hello to everyone on the list, > > To begin with, my overall goal is to build an adaptive modulation scheme using GnuRadio > and USRPs. Concept-wise, this will be implemented by calculating the BER at the receiver, > feeding this data to the transmitter, and switching between two different modulation > schemes based on threshold BER values. > > I am currently working on an 8DPSK modulation format. After succesfully building and > testing the flowchart in simulation, I split the transmit and receive chain in order to > actually test the setup using two B210 USRPs. > > After a little bit of experimentation, transmission is great when using a random source at > the transmitter. The FFT plot and the Constellation appear as expected. However, when > using a vector source, which is mighty helpful for my purpose since I have a known bit > sequence to compare at the receiver, my ouputs are unexpected (screenshots attached). This > is baffling because the only thing that changed is the bit sequence and nothing in the > actual signal processing chain (to be frank a packed to unpacked, and upacked to packed > block were used after the vector source, but I'm getting pretty much the same results > without them). I have experimented with different parameters but to no avail. It is > important to note, that the simulations were working fine, regardless of the source that > was used. > > Any thoughts on why this is happening? I have also attached screenshots of the flowcharts. > > Thank you very much for all the effort you are putting into the project. > > Best regards, > George > > |
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