Hello Alvin: Agree with what Nick said. Does the flowgraph run without overruns or underruns at 5 or 10 Msps?
Does your system have an NVMe solid-state disk? Also, have you done any performance tuning? http://files.ettus.com/manual/page_transport.html Have you set the read and write socket buffer sizes? sudo sysctl -w net.core.rmem_max=16777216 sudo sysctl -w net.core.wmem_max=16777216 Have you set the CPU governors to "performance" mode? Note that this must be done on a core-by-core basis. You also need to explicitly set the CPU clock speed to its maximum value. https://askubuntu.com/questions/20271/how-do-i-set-the-cpu-frequency-scaling-governor-for-all-cores-at-once https://ubuntuforums.org/showthread.php?t=2176315 --Neel Pandeya On 23 May 2018 at 00:12, Nick Foster <[email protected]> wrote: > For starters, you almost certainly cannot write to your hard drive at > 15Msps. You might not even be able to reliably read that fast without > underruns. > > Reduce the sample rate until things start working. Disable or simplify > parts of your flowgraph to see what's causing your problems. Isolate each > problem and understand it before moving on. Start simple and validate each > part instead of building something complex to start with. > > Nick > > On Wed, May 23, 2018, 8:02 AM Yeo Jin Kuang Alvin (IA) < > [email protected]> wrote: > >> Hi all, >> >> >> >> Btw in this flowgraph, I’ve noticed there is nothing transmitting out >> when I change the file source from repeat to no repeat. Originally, I >> thought the waveform stored in file sink is immediately transmitted out >> from file source and continue the process till I stop the flowgraph. >> >> >> >> When I on the repeat, signal starts transmitting out. Why is this so? >> >> >> >> Thank you in advanced! >> >> >> >> *From:* Kevin McQuiggin [mailto:[email protected]] >> *Sent:* Wednesday, 23 May 2018 11:35 AM >> >> >> *To:* Yeo Jin Kuang Alvin (IA) >> *Cc:* [email protected] >> *Subject:* Re: [Discuss-gnuradio] Underflow and Overflow >> >> >> >> Hi Alvin: >> >> >> >> >> >> >> >> On May 22, 2018, at 6:38 PM, Yeo Jin Kuang Alvin (IA) < >> [email protected]> wrote: >> >> I want to do a transceiver, so instead of receiving a signal elsewhere >> out of the board. I self-generate out a chirp signal internally in USRP >> B210 and do a loopback to the receive port and then re-transmit out using >> another transmit port. >> >> >> >> You will have to be very careful with this. Looping back the USRP output >> port back to the input port can blow the front end of the USRP receiver. >> Make sure that you use an external attenuator, not just a loopback cable. >> I would start with 30 dB. >> >> >> >> Please tell the group more about your “transceiver": this is a broad >> statement, what are you trying to achieve? There are several different >> types of transceivers and the implementation will depend upon the >> application you have in mind. >> >> >> >> Kevin >> >> >> >> >> >> >> >> Thank you in advanced! >> >> >> >> *From:* Kevin McQuiggin [mailto:[email protected] <[email protected]>] >> *Sent:* Wednesday, 23 May 2018 9:03 AM >> *To:* Yeo Jin Kuang Alvin (IA) >> *Cc:* [email protected] >> *Subject:* Re: [Discuss-gnuradio] Underflow and Overflow >> >> >> >> Hi Alvin: >> >> >> >> Well, for one thing, you are trying to write USRP output samples to a >> file at 30 MB per second. That is likely to generate overflows. >> >> >> >> Your flowgraph indicates to me that you haven’t fully internalized how >> gnuradio works and how it interacts with whatever front-end hardware you >> are using. >> >> >> >> Don’t take this comment as overly critical, we all (myself included) >> started with only basic understanding, and had to build our skills from >> there. >> >> >> >> I suggest going to the gnuradio web site and following, as a start, the >> set of tutorials that have already been recommended by others on the list. >> They will help you as you start to climb the learning curve! >> >> >> >> Kevin >> >> Sent from my iPhone >> >> >> On May 22, 2018, at 17:48, Yeo Jin Kuang Alvin (IA) <[email protected]> >> wrote: >> >> Does anyone know this? >> >> >> >> *From:* Discuss-gnuradio [mailto:discuss-gnuradio- >> [email protected] >> <[email protected]>] *On Behalf Of *Yeo >> Jin Kuang Alvin (IA) >> *Sent:* Tuesday, 22 May 2018 5:42 PM >> *To:* [email protected] >> *Subject:* [Discuss-gnuradio] Underflow and Overflow >> >> >> >> Hi all, >> >> >> >> May I know what causes my flowgraph to have so many U’s and O’s, is there >> any block that causes this? I am trying to hit a higher sampling rate >> possibly 20 MHz or higher. I have searched online and some suggest switching >> to a different OS and I did switch from windows to Ubuntu, only a >> slight difference. Some say is the computer’s processing speed not fast >> enough, thus, changing a better one will help. Others did mentioned that >> the flowgraph connection might cause this problem. >> >> >> >> I am getting “OOOUOO” when transmit a sine wave sampling at 20 MHz and >> receive to a file sink. >> >> >> >> I am using USRP B210, running on a Intel Core i7-4700MQ CPU @ 2.40 GHz x >> 8, 64 bit computer. >> >> >> >> Any help would be appreciated! >> >> >> >> <image001.png> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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