# TVRX2 and GRC **URL:** \ **Category:** GNU Radio\ **Created:** [October 3, 2014, 11:25pm UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349 "2014-10-03T23:25:43Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\ **Post date:** [October 3, 2014, 11:25pm UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/1 "2014-10-03T23:25:43Z")
Hello, ``` We have a new TVRX2, which we are using with a N200 USRP. The N200 ``` has a GPSDO. ``` The system seems to work fine when we test it with uhd_fft. ``` However, we are having trouble figuring out the correct configuration settings in for a custom GRC flow graph. The graph in question is simple, consisting of just the USRP and an FFT GUI, as shown in the first attached screen shot. ``` As the second attached screen shot shows, however, the system does ``` not run properly, producing a string of “DDDDD’s”, with the FFT window going dark. The warning that reads “Sensor ‘lo\_locked’ failed to lock within timeout on channel 0” seems like it might be related. ``` The 3rd and 4th screen shots show the setup menus for the USRP and ``` the FFT GUI. ``` Any advice on what might be going wrong would be greatly ``` appreciated. Sincerely, Dan Marlow ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 4, 2014, 1:31am UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/2 "2014-10-04T01:31:03Z")
> Sincerely, > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) > Unfortunately, those images are too small for my aging eyes to glean > useful data from them. ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 4, 2014, 1:33am UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/3 "2014-10-04T01:33:00Z")
> Sincerely, > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) > If you put your flow-graph itself (.grc file) somewhere, or attach it, > we can take a better look. What kind of comptuer? (OS, CPU/MEM specifics, etc). ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 4, 2014, 1:50am UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/4 "2014-10-04T01:50:26Z")
Dan, If you execute the various “sudo sysctl …” lines shown in the warnings, does it work any better? You can make these permanent. man sysctl.conf - Jeff ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 4, 2014, 8:24pm UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/5 "2014-10-04T20:24:54Z")
On Oct 3, 2014, at 7:30 PM, Marcus D. Leech wrote: > Shirleys Bay Radio Astronomy Consortium > [http://www.sbrac.org](http://www.sbrac.org) Hi Marcus, ``` Thanks. The .grc file is attached. Other details: o Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz o Memory 3GB o OS 14.1 Ubuntu ``` Cheers, Dan ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 4, 2014, 9:07pm UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/6 "2014-10-04T21:07:32Z")
> > – > > o Memory 3GB > > o OS 14.1 Ubuntu > > Cheers, > Dan Well, for one, your FFT block disagrees rather dramatically with your UHD source block about the same rate, which you’ve selected as 10Msps. I’d go for 6.25Msps, and make certain that your source block and FFT block agree on sample rate. And if you’re really wanting the 1.7MHz that you’ve programmed in the source to 1.7MHz, you don’t need more than about 2Msps sampling rate. Very few daughtercards have variable analog bandwidth, the TVRX2, DBSRX2, and perhaps XCVR are the only ones with variable analog baseband/IF bandwidth. ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 4, 2014, 8:27pm UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/7 "2014-10-04T20:27:29Z")
On Oct 3, 2014, at 7:49 PM, Jeff L. wrote: > Dan, > > If you execute the various “sudo sysctl …” lines shown in the warnings, does > it work any better? You can make these permanent. > > man sysctl.conf > > - Jeff Hi Jeff, ``` Thanks for the suggestion. We will give that a try. ``` Cheers, Dan ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 5, 2014, 12:40am UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/8 "2014-10-05T00:40:44Z")
> > – > > o Memory 3GB > > o OS 14.1 Ubuntu > > Cheers, > Dan I’ve attached updates to your graph that should make it behave more rationally: 2Msps sample rate – consistent with your programmed 1.7MHz analog bandwidth Deleted antenna spec in source block–it contained invalid specification Made the device address spec valid Moved things into user-changable variables: freq and gain Made both source and FFT use the “samp\_rate” variable, so changing that variable will change both source and FFT sink Made FFT sink turn on averaging, and use “freq” variable to set center frequency I’d suggest looking it over carefully, and comparing against what you originally had. ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 6, 2014, 8:15am UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/9 "2014-10-06T08:15:04Z")
On 10/03/2014 11:23 PM, Daniel M. wrote: > ``` > As the second attached screen shot shows, however, the system does > > ``` > > not run properly, producing a string of “DDDDD’s”, with the FFT window > going dark. The warning that reads “Sensor ‘lo\_locked’ failed to lock > within timeout on channel 0” seems like it might be related. On top of what Jeff + Marcus have said, that warning was a result of an over-zealous checking, which is removed in the latest version. Cheers, M ---
**Author:** ![danmcb](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/13edae/32.png) [@danmcb](https://www.ruby-forum.com/u/danmcb)\ **Post date:** [October 5, 2014, 2:02pm UTC](https://www.ruby-forum.com/t/tvrx2-and-grc/232349/10 "2014-10-05T14:02:39Z")
On Oct 4, 2014, at 6:39 PM, Marcus D. Leech wrote: > > > Marcus L. > > > o OS 14.1 Ubuntu > > > Made the device address spec valid > > > Principal Investigator > > > Shirleys Bay Radio Astronomy Consortium > > > [http://www.sbrac.org](http://www.sbrac.org) > > > \ Hi Marcus, ``` Many thanks. We will give that a try. ``` Cheers, Dan