One of the modulation techniques which convert digital value to the analog signal. One kind of phase deviation modulation technique which expresses information with combination of the plural waves where phase slips.

With BPSK, you use the sine wave which becomes standard and the wave where phase reverses, by the fact that 0, already on the one hand it makes 1 one side correspond, binaries (1 bit)information sending and receiving you are possible at one time. It is strongest in noise with simple phase deviation modulation technique, but as for transmission efficiency because it is bad, generally there is many a thing where QPSK which utilizesfour phases and 8PSK which utilizeseight phases are used.