# Signal drought **URL:** \ **Category:** GNU Radio\ **Created:** [May 6, 2014, 1:53am UTC](https://www.ruby-forum.com/t/signal-drought/240899 "2014-05-06T01:53:46Z")\ **Posts on this page:** 12\ **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:** [May 6, 2014, 1:53am UTC](https://www.ruby-forum.com/t/signal-drought/240899/1 "2014-05-06T01:53:46Z")
Hi, I built all the code today using the build-gnuradio script and when I create a simple GRC flow graph going from the USRP source to the waterfall plot, I get no data coming in. I then built gqrx and ran it and it too doesnt get any data in from the device to display on its waterfall. I ran the rx\_samples\_to\_file example and captured some data, but when looking at it in a hex editor, it doesnt look like it captured anything in particular ([http://test.utr-software.com/sdr/rxdump.dat](http://test.utr-software.com/sdr/rxdump.dat)). I ran it with ./rx\_samples\_to\_file freq=107700000 rate=1000000 file=~/rxdump.dat. I am new to gnu radio and sdr so Im not yet sure how to dig in to debug these issues. Anything help is greatly appreciated. Thanks, Greg ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 2:01am UTC](https://www.ruby-forum.com/t/signal-drought/240899/2 "2014-05-06T02:01:08Z")
On 05/05/2014 07:52 PM, Greg Hulands wrote: > Hi, > I built all the code today using the build-gnuradio script and when I create a > simple GRC flow graph going from the USRP source to the waterfall plot, I get no > data coming in. I then built gqrx and ran it and it too doesnt get any data in > from the device to display on its waterfall. I ran the rx\_samples\_to\_file example > and captured some data, but when looking at it in a hex editor, it doesnt look > like it captured anything in particular > ([http://test.utr-software.com/sdr/rxdump.dat](http://test.utr-software.com/sdr/rxdump.dat)). I ran it with ./rx\_samples\_to\_file > freq=107700000 rate=1000000 file=~/rxdump.dat. > > I am new to gnu radio and sdr so Im not yet sure how to dig in to debug these > issues. > > Anything help is greatly appreciated. > > Thanks, > Greg How about something really, really simple: uhd\_fft -a type=b200 -f 107.7e6 -s 1.0e6 -g 40 --fft-rate 8 --averaging – Marcus L. Principal Investigator Shirleys Bay Radio Astronomy Consortium > **[Live Draw HK Tercepat | Result HK | HK Pools | Live HK | HK Prize Hari Ini](https://www.sbrac.org)** > > Temukan live draw hk tercepat melalui halaman hk pools yang resmi dan dapatkan result hk prize melalui live hk secara langsung di situs kami. ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 2:04am UTC](https://www.ruby-forum.com/t/signal-drought/240899/3 "2014-05-06T02:04:50Z")
It just looks like noise. ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 2:41am UTC](https://www.ruby-forum.com/t/signal-drought/240899/4 "2014-05-06T02:41:11Z")
> It just looks like noise. Well, “noise” isn’t the same as “no signal at all”. Do you _expect_ there to a signal at 107.7MHz? Do you have an antenna plugged in to the correct port on the device? > > > Thanks, > > > [http://www.sbrac.org](http://www.sbrac.org) > > > > * * * > > > > Discuss-gnuradio mailing list > > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) – Marcus L. Principal Investigator Shirleys Bay Radio Astronomy Consortium > **[Live Draw HK Tercepat | Result HK | HK Pools | Live HK | HK Prize Hari Ini](https://www.sbrac.org)** > > Temukan live draw hk tercepat melalui halaman hk pools yang resmi dan dapatkan result hk prize melalui live hk secara langsung di situs kami. ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 2:45am UTC](https://www.ruby-forum.com/t/signal-drought/240899/5 "2014-05-06T02:45:29Z")
> I changed antennas and I see a signal now in uhd\_fft. I just noticed that when > in GRC and I run the flow graph, i dont see the RX light come on the board like > when running uhd\_fft. > > I have put the grc file up here [http://test.utr-software.com/sdr/test.grc](http://test.utr-software.com/sdr/test.grc) > > Thanks, > Greg The default antenna port if you don’t specify one is always TX/RX – because you might be wanting to do half-duplex. You can explicitly specify the RX2 antenna port in the GRC source block, or just remember that “unspecified” means, typically, TX/RX. > > > > I am new to gnu radio and sdr so Im not yet sure how to dig in to debug these > > > > issues. > > > > – > > > > * * * > > > > Discuss-gnuradio mailing list > > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > > [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) – Marcus L. Principal Investigator Shirleys Bay Radio Astronomy Consortium > **[Live Draw HK Tercepat | Result HK | HK Pools | Live HK | HK Prize Hari Ini](https://www.sbrac.org)** > > Temukan live draw hk tercepat melalui halaman hk pools yang resmi dan dapatkan result hk prize melalui live hk secara langsung di situs kami. ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 2:42am UTC](https://www.ruby-forum.com/t/signal-drought/240899/6 "2014-05-06T02:42:25Z")
I changed antennas and I see a signal now in uhd\_fft. I just noticed that when in GRC and I run the flow graph, i dont see the RX light come on the board like when running uhd\_fft. I have put the grc file up here [http://test.utr-software.com/sdr/test.grc](http://test.utr-software.com/sdr/test.grc) Thanks, Greg ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 2:53am UTC](https://www.ruby-forum.com/t/signal-drought/240899/7 "2014-05-06T02:53:27Z")
* * * Discuss-gnuradio mailing list removed\_email\_address@domain.invalid [https://lists.gnu.org/mailman/listinfo/discuss-gnuradio](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 3:00am UTC](https://www.ruby-forum.com/t/signal-drought/240899/8 "2014-05-06T03:00:12Z")
> I changed to RX2 and still not activating the receiver on the board. Try changing the “Wire Format” to complex-int16 ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 3:12am UTC](https://www.ruby-forum.com/t/signal-drought/240899/9 "2014-05-06T03:12:29Z")
* * * Discuss-gnuradio mailing list removed\_email\_address@domain.invalid [https://lists.gnu.org/mailman/listinfo/discuss-gnuradio](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 2:49am UTC](https://www.ruby-forum.com/t/signal-drought/240899/10 "2014-05-06T02:49:10Z")
* * * Discuss-gnuradio mailing list removed\_email\_address@domain.invalid [https://lists.gnu.org/mailman/listinfo/discuss-gnuradio](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio) ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 3:18am UTC](https://www.ruby-forum.com/t/signal-drought/240899/11 "2014-05-06T03:18:37Z")
On 05/05/2014 09:11 PM, Greg Hulands wrote: > Just use a subdev spec of A:A Are you getting any error messages when you run the graph? ---
**Author:** ![Greg\_Hulands](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/f17d59/32.png) [@Greg\_Hulands](https://www.ruby-forum.com/u/Greg_Hulands)\ **Post date:** [May 6, 2014, 3:21am UTC](https://www.ruby-forum.com/t/signal-drought/240899/12 "2014-05-06T03:21:05Z")
I just worked it out - the run parameter in the Options block was set to Off instead of autostart. Doh. Thanks so much for your help. I really appreciate it. Cheers, Greg