# Using uhd\_fft with USRP1 **URL:** \ **Category:** GNU Radio\ **Created:** [April 29, 2014, 10:00pm UTC](https://www.ruby-forum.com/t/using-uhd-fft-with-usrp1/240764 "2014-04-29T22:00:20Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\ **Post date:** [April 29, 2014, 10:00pm UTC](https://www.ruby-forum.com/t/using-uhd-fft-with-usrp1/240764/1 "2014-04-29T22:00:20Z")
Ok, I got the address correct, I know the usrp and daughtercard are there. I can’t get the simplest uhd\_fft to run from GRC. I get the following message on trying to execute, Generating the graph works. – Opening a USRP1 device… – Using FPGA clock rate of 64.000000MHz… Using Volk machine: avx\_64\_mmx\_orc thread[thread-per-block[0]: \]: LookupError: KeyError: Cannot find an item size: The error output, as usual, has no meaning for me, entirely arcane. I’m running Ubunu 12.04.4 64 bit and gnuradio installed without a burp. Actually, the error message looks like something to do with multithreading. I tried the archives, no help. uhd\_usrp\_probe says the usrp1 is there and reports the daughterboards that are really there. so, need an interpreter, please. Thanks, Don – “The power of accurate observation is commonly called cynicism by those who have not got it.” -George Bernard Shaw Dr. Don L. AJ7LL Six Mile Systems LLC 17850 Six Mile Road Huson, MT, 59846 mail: POBox 404 Frenchtown MT 59834-0404 VOX 406-626-4304 Skype: buffler2 [www.lightningforensics.com](http://www.lightningforensics.com) [www.sixmilesystems.com](http://www.sixmilesystems.com) ---
**Author:** ![Don\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@Don\_L](https://www.ruby-forum.com/u/Don_L)\ **Post date:** [April 29, 2014, 10:18pm UTC](https://www.ruby-forum.com/t/using-uhd-fft-with-usrp1/240764/2 "2014-04-29T22:18:40Z")
Hey Don, this is a bug in UHD, which is fixed on the current ‘master’. If you’re using ‘master’, you can simply update UHD and reinstall (git pull etc.). If you can’t update for some reason right now, --wire-format=sc16 might help. Cheers, Martin ---
**Author:** ![Don\_L](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@Don\_L](https://www.ruby-forum.com/u/Don_L)\ **Post date:** [April 29, 2014, 11:03pm UTC](https://www.ruby-forum.com/t/using-uhd-fft-with-usrp1/240764/3 "2014-04-29T23:03:36Z")
It is also fixed on maint for 003.007.001. Regards, Andy