A simple AM radio receiver consists of five main functional blocks as shown below:
Antenna
Every radio receiver requires an antenna (aerial) as the input, to convert the incoming
radio waves into tiny alternating currents. Unlike the transmitting aerial which may only
be transmitting one frequency from the radio station, the aerial will pick up all of the
different radio broadcasts at different carrier frequencies within range. The actual current
variation in the aerial will be a complex mixture of all these signals and so the first thing
the receiver has to be designed to do is select one broadcast from among the many, and
then extract its audio information.
The tuning circuit
A tuning circuit is essentially a band pass filter designed to pick up carrier frequencies
typically in the range 300 kHz to 3MHz. The frequency range (i.e. the frequency band it
passes) can be altered by means of a variable capacitor. The frequency response of the
tuning circuit is the gain as a function of frequency, where
Antenna
Every radio receiver requires an antenna (aerial) as the input, to convert the incoming
radio waves into tiny alternating currents. Unlike the transmitting aerial which may only
be transmitting one frequency from the radio station, the aerial will pick up all of the
different radio broadcasts at different carrier frequencies within range. The actual current
variation in the aerial will be a complex mixture of all these signals and so the first thing
the receiver has to be designed to do is select one broadcast from among the many, and
then extract its audio information.
The tuning circuit
A tuning circuit is essentially a band pass filter designed to pick up carrier frequencies
typically in the range 300 kHz to 3MHz. The frequency range (i.e. the frequency band it
passes) can be altered by means of a variable capacitor. The frequency response of the
tuning circuit is the gain as a function of frequency, where
