Kendall effect

In telecommunication, a Kendall effect is a spurious pattern or other distortion in a facsimile record copy caused by unwanted modulation products arising from the transmission of a carrier signal, and appearing in the form of a rectified baseband that interferes with the lower sideband of the carrier.

Note: The Kendall effect occurs principally when the single-sideband width is greater than half of the facsimile carrier frequency.

Source: from Federal Standard 1037C and from MIL-STD-188