quarternary phase-shift keying

quarternary phase-shift keying

[′kwät·ə‚ner·ē ′fāz ‚shift ‚kē·iŋ]
(electronics)
Modulation of a microwave carrier with two parallel streams of nonreturn-to-zero data in such a way that the data is transmitted as 90° phase shifts of the carrier; this gives twice the message channel capacity of binary phase-shift keying in the same bandwidth. Abbreviated QPSK.