RECEIVERS

Figure 1-5.—FM transmitter block diagram. We can make ssb even more efficient by removing one of the sidebands. By filtering out one of the side- bands before it reaches the power amplifier, all the transmitter energy is concentrated into one side- band instead of being split between the carrier and two sidebands. This allows us to use less power for transmission. Other advantages are a narrower re- ceiver bandpass and the ability to place more signals in a small portion of the frequency spectrum. Figure 1-6 is a block diagram of a ssb transmitter. RECEIVERS Earlier you were introduced to one link in a com- munications system, the transmitter. All that is needed to complete the system is a radio receiver. A receiver processes modulated signals and delivers, as an output, a reproduction of the original intelligence. The signal can then be applied to a reproducing device, such as a loudspeaker or a teletypewriter. RECEIVER FUNCTIONS To be useful, a receiver must perform certain basic functions. These functions are reception, selection, de- tection, and reproduction. Reception Reception occurs when a transmitted electromag- netic wave passes through the receiver antenna and in- duces a voltage in the antenna. Figure 1-6.—SSB transmitter block diagram. 1-7