In facsimile, a frequency modulationsystem where one frequency represents picture black and another frequency represents picture white[?]. Frequencies between these two limits may represent shades of gray
An intentional frequency change used for modulation purposes
... the census of 2000, there are 1,526 people, 605 households, and 434 families residing in the town. The population density is 133.3/km² (345.1/mi²). There are ...