使用全頻段發射信號

FHMA (frequency hopped multiple access)

Invented by George Antheil (a composer)
Hedy Lamarr (an actress, 1913–2000)

Antheil and Lamarr submitted the idea of a secret communication system in June 1941. On August 11, 1942, U.S. Patent 2,292,387 was granted to Antheil and "Hedy Kiesler Markey", Lamarr's married name at the time. This early version of frequency hopping used a piano roll to change between 88 frequencies and was intended to make radio-guided torpedoes harder for enemies to detect or jam.

DSMA (direct sequence multiple access)：又稱為CDMA (code division multiple access)