Steps to convert received radio signal to audio in a radio receiver. There are many transmission and receiver technologies. This is just one of the simple explanation how radio waves are received and converted into voice.
Radio signal is received through an antenna, another frequency is generated locally and both are fed into mixer which produces difference frequency of both frequencies. That frequency generated will always kept at the frequency the ‘IF amplifier’ is set at. The amplified IF (intermediate frequency) is fed to demodulator where radio frequency part gets removed and demodulated audio frequency remains. Obtained audio signal is amplified and then heard through a speaker or headphone.
Example circuit diagram of radio receiver :
This is example of radio receiver for specific frequency but it has stages mentioned in the block diagram above. Local oscillator is using crystal (x1) and received signal is mixed in FET mixer BF244B transistor. Detection and Audio amplifier output is ready to fed into speakers to be connected to ‘audio out’.
This time, ‘radio on a chip’ ICs are available to do all functions with minimum external components. High quality receivers in a very compact size can be made using such special purpose radio receiver ICs. Check few circuit diagrams and see how those ICs do almost all functions of a radio receiver.