What undesirable effect can occur when using a noise blanker?

A noise blanker is designed to eliminate short, sharp impulse noise, such as automotive ignition sparks or power line arcs. It accomplishes this by detecting the high-amplitude voltage spike and momentarily turning off (blanking) the receiver's intermediate frequency (IF) amplifier before the noise can reach the audio output. The blanker's detection circuit is typically wideband. If there are strong, legitimate signals on nearby frequencies, these signals can trigger the noise blanker or be chopped up by its rapid switching action. This high-speed on-and-off switching mixes with the strong adjacent signals, creating severe intermodulation distortion. To the operator, this distortion makes it sound as though the adjacent strong signals are splattering or transmitting spurious emissions across the band. Therefore, a noise blanker should only be used when impulse noise is actively present, and turned off otherwise.