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git-artes / gr-isdbt

DTV ISDB-T in GNURadio
http://iie.fing.edu.uy/investigacion/grupos/artes/gr-isdbt/
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Overflow and Underflow Issue #41

Open ceeae10 opened 4 years ago

ceeae10 commented 4 years ago

Hello Artes Team!

I have reached another bottleneck with my research and I would like to ask for your help. I'm currently executing your flowgraph on the Receiver(with Full measurements) and the Transmitter. I didn't change any of the parameters and just executed it as it is. However, the transmission wasn't going as expected. I was not necessarily able to receive the video file since the byte count was fewer than 10 kbytes. When examining the diagrams, I have no clear diagram of the constellation though there were random shows of the signal being received as shown in the video attached. The USRP also indicates that it was not continuously receiving as seen in blinking led on the circuit board shown on the other attached video. The GNU Radio also printed U's in Transmitter side and O's on the receiving side, indicating underflows and overflow happening.

USRP Board when Receiving Constellation Diagram and Signal Graph

One theory that I have is that my laptops are not able enough to process the data being transmitted. With this, I have increased the allocation of the core and memory for my Virtual Machines. I have also done several ways to check the functionality of my boards such as an FM Tranceiver and USRP tests. To give you context on my set up, I have two laptops, one with i5 10 gen and one with i3 7th gen, and both of them using VMware Workstation Pro for the dual boot so that I can use Ubuntu 18.04. I'm using 2 USRP B200 and a Log Periodic Antenna.

I was wondering if you have encountered a similar situation and would be able to know to go around with this current situation. I would really be grateful for your help

git-artes commented 4 years ago

Hi, You should avoid using virtual machines, specially with this system that requires high throughput. In the second video it seems that the signal is being transmitted intermittently, as the spectrum goes up and down. Moreover, as you say yourself, Us and Os are also signs of problems on the transmission I would thus recommend installing an Ubuntu directly into the machine and try again.