Originally Posted by mmarshall

Baseball is not broadcast on FM?

Originally Posted by speedkar9

I took apart a Toyota radio to see what's inside and how it works. I made a short video on the simplified way it works, of course new radios are more complex:

https://www.youtube.com/watch?v=piX-_g7-mXo

The radio I took apart was a single DIN, AM/FM/CD radio:



Radio lid removed:



The main motherboard has a number of main components that make up the radio, including the antenna input, the demodulator, tuner, equalizer, micro-controller, amplifier, communication bus controller, human interface input/output, power distribution and CD ROM input:



Here's an overall system diagram of how things are laid out and work inside the radio:



Here's a closer look at the radio tuner (digital) and the demodulator:



If you remember physics class, AM stands for amplitude modulation, and FM stands for frequency modulation. Basically the amplitude or frequency of the radio waves are varied in order to carry a signal, which the demodulator turns into a voltage audio signal:



This is the back of the human interface board, including the LCD driver and buttons:



Moving on to the CD drive, there's 3 motors, one to turn the CD, one to load the tray, and one to move the laser head along the radius of the disk:



Closer look at the laser head:



Here's an overview of how it works, essentially light is reflected back based on the information burned onto the disk. A photo sensor pics up this light and turns that into usable information:





The last piece to a stereo is its output in the form of sound. This is done by repeatedly moving a paper cone back and forth at high frequency. This creates pressure waves in the air which we hear as sound.

The paper cone is controlled by an electromagnet:



And that's pretty much the very basics of how a car stereo works!



- Enjoy