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
... average household size is 2.38 and the average family size is 2.94.
In the city the population is spread out with 22.4% under the age of 18, 8.5% from 18 to 24, 24.9% ...