Binary Phase Shift Keying - 1 bit per symbol
Encoding: Binary 0 maps to +1 (0° phase), Binary 1 maps to -1 (180° phase shift).
Constellation: BPSK has only 2 points on the real axis, maximally separated.
Bit Rate: 1 bit per symbol. If symbol rate is R, bit rate is also R.
Noise Performance: Best noise immunity among PSK schemes due to maximum symbol separation.
Applications: Deep space communication, CDMA pilot channels, GPS.