have been assigned adjacent channels. Interference
occurs when the carrier frequency or sideband
frequency of the interferer is within the bandpass of a
Figure 2-8. Adjacent-channel interference.
(b ) Intermediate-frequency interference. A form
of interference known as intermediate frequency (IF)
Figure 2-7. Cochannel interference.
interference may occur if a high-amplitude signal at the
receiver IF reaches the mixer or IF stage (fig 2-9)
through the receiver antenna and front end, or through
the equipment case or cabling. Since the IF of a
receiver normally remains constant through the tuning
range of the receiver, this type of interference is
characterized by its presence at all tuned frequencies of
Figure 2-9. Intermediate-frequency interference.