[PDF] Chapter 4: AM Transmitters Figure 4-1: Low Level AM Transmitter Block Diagram. There are two signal paths in the transmitter, audio frequency (AF) and radio frequency (RF). The RF signal is created in the RF carrier oscillator. At test point A the oscillator's output signal is present. Analog Communication - Transmitters - Tutorialspoint AM Transmitter AM transmitter takes the audio signal as an input and delivers amplitude modulated wave to the antenna as an output to be transmitted. The block diagram of AM transmitter is shown in the following figure.