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
... 313 families residing in the town. The population density is 326.2/km² (842.9/mi²). There are 928 housing units at an average density of 173.1/km² ...