The traditional Noise Blanker detects the noise amplitude and timing in the first Intermediate Frequency (1st IF) stage of a superheterodyne receiver. The Noise Blanker then counters the noise by interrupting the signal path to the subsequent stages of the receiver for a short duration (milliseconds) that equals the duration of each noise pulse. This effectively cancels, or blanks out the noise. It might be considered as destructive interference, but true destructive interference uses phase cancellation. The noise blanker is literally chopping out the portions of the signal that contain the noise pulses.

Some radios include an additional wide-mode noise blanker. The regular noise blanker can usually handle power line noise or automotive ignition noise. Other noise, such as that from certain LED light bulbs, wall-wart power supplies, Plasma TVs, wireless phone chargers, garden lamps, greenhouse lamps, etc., can sometimes be minimized with the wide noise blanker, though they usually cannot be completely eliminated.

Some modern transceivers handle the pulse type noise in the digital domain (i.e. DSP). A SDR will deal with the noise in the digital domain, because the SDR has no IF stage.

Try to use only the lowest noise blanker level possible, especially with the wide noise blanker. A noise blanker can adversely affect the selectivity of a receiver, and the quality of the received audio. These adverse affects are even more noticeable with the wide noise blanker.

It is best to only use a noise blanker to temporarily mitigate the problem until the noise can be eliminated at the source.

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