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Question asked by komo Employee on Oct 12, 2015
Latest reply on Oct 20, 2015 by larsc

I am trying to demonstrate the FMCOMMS FM Radio demo described here:  HowTo: observe the FM band with an AD9361-equipped board [Analog Devices Wiki]

I am using the FMCOMMS4/Zedboard setup with an FM radio antenna connected to the broadband Rx port.


I can observe the FM radio spectrum on the IIOScope and have many strong signals.

When I execute iio_fm_radio_play in the console, I hear very clear audio on the HDMI monitor but it is very choppy and not continuous.


I have attached a screenshot of the console showing the output from iio_fm_radio_play.  It shows continuous underrun!!! errors (?) that might be the reason for the choppy audio.  Can you explain this?



Additionally, is there any documentation for iio_fm_radio_play?  Perhaps there are some switches that I am not aware of?

Separately, I get permission errors if I try to pipe the audio data to the headphone jack using the "iio_fm_radio 95.5 | aplay -D default:CARD=ADAU1761 -r 48000 -f S16" command.


I would like to demonstrate clear, continuous audio on either the HDMI monitor speakers or the headphone jack.  Please let me know if this is possible and how to properly demonstrate.