Analog Communication - Receivers

The antenna present at the beginning of the receiver section, receives the modulated wave. First let us discuss the requirements of a receiver.

Requirements of a Receiver

AM receiver receives AM wave and demodulates it by using the envelope detector. Similarly, FM receiver receives FM wave and demodulates it by using the Frequency Discrimination method. Following are the requirements of both AM and FM receiver.

· It should be cost-effective.

· It should receive the corresponding modulated waves.

· The receiver should be able to tune and amplify the desired station.

· It should have an ability to reject the unwanted stations.

· Demodulation has to be done to all the station signals, irrespective of the carrier signal frequency.

For these requirements to be fulfilled, the tuner circuit and the mixer circuit should be very effective. The procedure of RF mixing is an interesting phenomenon.

RF Mixing

The RF mixing unit develops an Intermediate Frequency (IF) to which any received signal is converted, so as to process the signal effectively.

RF Mixer is an important stage in the receiver. Two signals of different frequencies are taken where one signal level affects the level of the other signal, to produce the resultant mixed output. The input signals and the resultant mixer output is illustrated in the following figures.

Let the first and second signal frequencies be [Math Processing Error]