double frequency shift keying

double frequency shift keying

[¦dəb·əl ′frē·kwən·sē ¦shift ′kē·iŋ]
(communications)
Multiplex system in which two telegraph signals are combined and transmitted simultaneously by a method of frequency shifting between four radio frequencies.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.