Hello Yeo Jin,
First, find the maximum effective sampling rate that you can achieve with your computer. Connect a constant source to a USRP sink (for USRP sink underruns), or connect a USRP source to a null sink (for USRP source overruns) and run the flow graph. Try different sampling rates to find the maximum achievable sampling rate for your hardware (max samp rate that gives no underruns or overruns). If the maximum stable sampling rate that you can achieve is still 4MS/s, then you are pretty much out of luck. You can try installing different versions of GNU Radio and UHD (older version/newer version, version with AVX support, etc) and then try again. If that does not help (very likely), then you WILL have to upgrade your computer. In some cases, using a different network card (for network-based USRPs) or USB card (for USB-based USRPs) may improve the achivable rate (when the bottleneck is the link between the USRP and the PC). If that doesn't work either, then you will have to get a faster machine. If you can achieve a higher sampling rate with the simple flow graphs stated above, then the problem is the maximum throughput of your code. You can try optimizing your GNU Radio flow graphs and blocks. Try using simpler filters, and parallelize the bottlenecks within your flow graphs if possible (so as the CPU usage would go up to approx. 100% during the execution). You can run top and press H to see which block is taking the most CPU time (assuming a typical GNU/Linux distro). If you do not need to generate your I-Q data in real time, then generate your data before the execution of the flow graph and simply play back the pre-generated data (with a File Source block). You can also push down some of your DSP logics to the FPGA of the USRPs, if you have licences for the needed software (and if you are okay with HDL). Regards, Kyeong Su Shin ________________________________ 보낸 사람: Yeo Jin Kuang Alvin (IA) via USRP-users <usrp-users@lists.ettus.com> 대신 USRP-users <usrp-users-boun...@lists.ettus.com> 보낸 날짜: 2018년 5월 4일 금요일 오후 6:29:09 받는 사람: usrp-users@lists.ettus.com 제목: [USRP-users] USRP Underruns "UUUUU" Hi all, I am getting underruns and overruns when trying to run the UHD programs, both GNU radio and C++. The maximum my computer can handle is 4MHz sampling rate before seeing “UUUUU”. I’ve searched online and most people say, change a new computer into quad core etc. Are there any other ways to solve this problem? I want to hit around 20 MHz, but 30 MHz – 40MHz if possible. Thank you in advance!
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