BPSK

Binary Phase Shift Keying uses two phases (0 and 180 degrees), carrying 1 bit per symbol. Phase-shift keying (PSK) works by varying the phase of the carrier signal — the position of the waveform within its cycle. The receiver compares the received phase to the expected phase to determine which symbol was sent. BPSK is the simplest and most noise-tolerant PSK scheme. Used on links where the signal is weak relative to noise (low signal-to-noise ratio, or SNR).