Section 3
Transmitters and Receivers

Receiver concepts

3H1 Recall that the function of a radio receiver is to recover information sent from one place to another using electromagnetic radiation/wireless technology.

The block diagram above shows all the stages of a Radio Receiver. In coming at the aerial (antenna) is the RF which are Electromagnetic Radiation (or Radio waves) which is also called wireless technology as no wires connect the transmitter to the receiver

Recall that the process of recovering information from a modulated radio frequency signal is known as demodulation.

Being in amateur radio you have to expect terminology which you may not have come across before and in a radio receiver the process of recovery ( making sense of the modulated radio frequency (RF) signal is called Demodulation.

3H2 Identify the items in a simple receiver block diagram and recall their order of interconnection: Antenna, feeder, wanted signal selection and RF amplification, demodulation/detection, audio amplification and loudspeaker or headphones.
Note: See table 2

In the diagram at the start of this section is a simple block diagram of a radio receiver.

The RF signal enters the receiver via the aerial and the aerial attaches to the receiver by a piece of feeder often coaxial cable.

This first stage is known as the tuning and RF amplification stage. The signal as the incoming signal is very weak it has to amplify and then selects (or tunes) for the wanted signal. Just as with the Transmitter the tuning dial is part of this stage and like with tuning a portable radio into the station the same has to occur when you want to listen to amateur radio stations.

The origin of some of the text on this page is from the RSGB with additions by the web master