Hi –
I received two Pimoroni Pirate Radio kits for Christmas and, although they work, the
audio is really, really scratchy. I’ve run though the forums and can’t find anyone
whose had the same problem.
I followed the mechanical assembly instructions at
https://learn.pimoroni.com/tutorial/sandyj/assembling-pirate-radio
which went quite well. I then installed Raspian Stretch lite
(2017-11-29-raspbian-stretch-lite.zip), then followed the instructions
to install Pirate Radio at
https://learn.pimoroni.com/tutorial/sandyj/internet-radio-on-your-pirate-radio
which also went well. I was able to add my own radio stations and to SSH into
the Raspi, so all was well.
However, I was very unsatisified with the audio, which sounds clipped and
scratchy. I replaced the Pirate Radio speaker with a different, higher-quality
speaker. No joy. I then connected an oscilloscope across the two terminals of the
original Pirate Radio speaker and saw:
DS1Z_QuickPrint1.png
which was not what I was expecting. The volume was fairly low at this point
(only one LED of the VU meter lit). Zooming in on waveform above revealed:
DS1Z_QuickPrint2.png
(See next post. New users can upload only one image per post)
which is a pulsed signal at about 650 kHz. I tried several variations of
radio stations and re-installed a couple of times. No joy.
When I run
speaker-test -t sine -f 1000
which generates a 1 kHz sine wave, I see the following across the speaker
terminals:
DS1Z_QuickPrint7.png
(See next post. New users can upload only one image per post)
I have two Pimoroni Pirate Radio kits and they both behave the same. Of course, I
could have made the same mistake on both of them.
Any help? Thanks.
Kevin