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
... sent to Hawaii, where he was ordained on May 24, 1864. On May 10, 1873, at his request, he was permitted to travel to Molokai to help the lepers who had virtually nothing ...