Quadrature Phase Shift Keying

/ˌkjuː piː ɛs keɪ/

noun … “quadrature phase shift keying.”

QPSK is a digital modulation technique that encodes two bits per symbol by varying the phase of a carrier wave among four discrete states, typically 0°, 90°, 180°, and 270°. By using four phases instead of the two in BPSK, QPSK doubles the data rate for the same bandwidth while maintaining robustness to noise and interference.

Binary Phase Shift Keying

/ˌbiː piː ɛs keɪ/

noun … “binary phase shift keying.”

BPSK is a digital modulation technique that encodes binary data by shifting the phase of a carrier wave between two discrete states. Each state represents one bit … typically a phase of 0 degrees for binary 1 and 180 degrees for binary 0. Because only two phases are used, BPSK is conceptually simple, mathematically elegant, and exceptionally robust in noisy environments.

FHSS

/ˌɛf eɪtʃ ɛs ɛs/

n. "Pseudo-random carrier frequency switching spreading narrowband signal across wide spectrum for Bluetooth anti-jamming."