I connected a Raspberry Pi 2 in the car to add OSMC media player capabilities. However, there seems to be a buzz / hum of background noise in the audio. The noise is correlated to the engine speed so it seems to be coming from the Alternator.
What are some different method of fixing this?
There ended up being 2 issues to solve in fixing the background noise issue.
1) I bought a ground loop noise isolator. Put this in line with he RCA audio cable, with ground lead connected to the cars battery ground.
Here's the noise isolator I bought: http://www.amazon.com/gp/product/B000K50HJE
2) The 12v to USB power adapter / converter I was using initially was a really cheap one that wasn't providing good power to the Raspberry Pi. I replaced this with a much better one.
Never use cheap USB power adapters. Here's the USB power adapter I bought: http://www.amazon.com/gp/product/B00VH8VHWO
After making these 2 changes to the system, the audio no longer has any hum or background noise.
I moved the USB connector from my 5V audio supply adapter to RPI USB port. That eliminated the buzz totally. The problem may be same for you, if you take the power from two separate 12V to 5V power supplies.
