I have connected a TEA5767 to my Arduino board using I2C and can tune it fine (see instructable.com). As antenna a ~70cm long simple cable is connected. I've connected a cheap 5V amplifier. Unfortunately, the sound quality is bad – very much static noise (though the sender is only 2km air distance away) – with forced mono it is acceptable but still not good. When scanning for stations (muted) there also is noise. Disconnecting the inputs of the amplifier causes absolutely no noise.
Update according to the comments:
When using the FM application on my Motorola/Android phone and put it near the Arduino, it does not cause noise, so the Arduino seems not to "send" – but maybe it is caused by the connected VCC? I've put a 100nF and a 100uF capacitor near the FM receiver and amplifier – it makes absolutely no difference. For me it looks like the TEA5767 causes the noise.
Does someone has an idea how to improve the sound quality?
Best Answer
Your mention of the audio still having noise when you are "scanning station (muted)", leads me to believe the problem could be your "cheap" audio amplifier.
However, it is difficult to reconcile why you get acceptable audio when forced mono.
Try putting a de-coupling capacitor (perhaps 0.1 uf) across the +5 volts of your audio amplifier (+5v to board ground). Put the capacitor right on the amplifier board if you can.