# FM Receiver doesn't work **URL:** \ **Category:** GNU Radio\ **Created:** [February 19, 2014, 7:47am UTC](https://www.ruby-forum.com/t/fm-receiver-doesnt-work/239254 "2014-02-19T07:47:14Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Detlef\_R](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/58f4c7/32.png) [@Detlef\_R](https://www.ruby-forum.com/u/Detlef_R)\ **Post date:** [February 19, 2014, 7:47am UTC](https://www.ruby-forum.com/t/fm-receiver-doesnt-work/239254/1 "2014-02-19T07:47:14Z")
Hello, My system: WBX motherboard, B100, 2007 Macbook Pro 10.8.5 2.4 ghz core duo 4gb 1067mhz ddr3. I am new here. I have tried to build several FM receiver flow graphs - Taken from the Ettus website, Ettus Youtube page and other sources too. I get the same problem every time… no signal past the wbfm receiver. I am convinced it must be something with the wbfm receiver block. Ettus tech support guys had me investigate sample rates and WX vs QT components, so I reduced sample rates as much as possible and ran both WX and QT configurations with no change. I’ve gotten simple flow graph examples to output audio and every block that I’ve tried seems to do something except wbfm receiver. The Ettus guys were able to run my flowgraph (with audio output from wbfm receiver) when I emailed it. I just updated everything on macports and the issue still persists. What can I be doing wrong? I won’t attach a file until someone asks me to, since I’m not familiar with etiquette. Thanks, Stephan Vanwoezik removed\_email\_address@domain.invalid [www.trapadulli.com](http://www.trapadulli.com) Delray Beach, FL 33444 (310)210-3814 Stephan Vanwoezik removed\_email\_address@domain.invalid [www.trapadulli.com](http://www.trapadulli.com) Delray Beach, FL 33444 (310)210-3814 ---
**Author:** ![stephan\_vanwoezik](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/3bc359/32.png) [@stephan\_vanwoezik](https://www.ruby-forum.com/u/stephan_vanwoezik)\ **Post date:** [February 19, 2014, 9:08am UTC](https://www.ruby-forum.com/t/fm-receiver-doesnt-work/239254/2 "2014-02-19T09:08:23Z")
On Wed, Feb 19, 2014 at 12:46 AM, stephan vanwoezik [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > change. > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [www.trapadulli.com](http://www.trapadulli.com) > Delray Beach, FL 33444 > (310)210-3814 > Stephan Vanwoezik > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > [www.trapadulli.com](http://www.trapadulli.com) > Delray Beach, FL 33444 > (310)210-3814 What version of GNU Radio are you running (check with gnuradio-config-info -v). There was a bug that crept in to the fast\_atan2f function (it was my fault and I’ve been seriously regretting it…) in the latest release that was fixed about a week after it was introduced. The symptoms are most noticeable when receiving low power FM signals since you get all 0s out. See this thread for more details: > **[Re: \[Discuss-gnuradio\] quadrature\_demod losing weak signals](https://lists.gnu.org/archive/html/discuss-gnuradio/2013-11/msg00514.html)** Nathan ---
**Author:** ![stephan\_vanwoezik](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/3bc359/32.png) [@stephan\_vanwoezik](https://www.ruby-forum.com/u/stephan_vanwoezik)\ **Post date:** [February 19, 2014, 9:37am UTC](https://www.ruby-forum.com/t/fm-receiver-doesnt-work/239254/3 "2014-02-19T09:37:15Z")
On 02/19/2014 07:46 AM, stephan vanwoezik wrote: > WX and QT configurations with no change. > Can you see an FM spectrum (using a QT GUI Frequency sink behind the > USRP source block)? > I’ve gotten simple flow graph examples to output audio and every block > that I’ve tried seems to do something except wbfm receiver. The Ettus > guys were able to run my flowgraph (with audio output from wbfm > receiver) when I emailed it. I just updated everything on macports and > the issue still persists. What can I be doing wrong? I won’t attach a > file until someone asks me to, since I’m not familiar with etiquette. Thanks for being polite about this! In general, you can attach small files. For GRC, screenshots are sometimes useful, and should be posted to an image hosting service, such as imgur. Long text output goes onto pastebin. Martin