Phase modulation is also a technique that is been used for doing encoding in of analog signal into analog data using a digital transmission coding scheme that lie in the wide range of latest technologies like WiFi,GSM and satellite television.

Phase modulation is much more similar to the frequency modulation (FM), it is considered as a step to achieve FM .These both phases are being considered special case of quadrature amplitude modulation (QAM).

Phase modulation is for digital synthesiztion of signal and the carrier waveform like the DX7 to implement FM synthesizes.

In this modulation technique, we vary the phase of the carrier to reflect voltage level change of analog signal.

Phase modulation is very much similar to the Frequency Modulation technique, but in the phase modulation the frequency of carrier is not increased anyhow. Frequency is changed to reflect the change in the amplitude of the modulating signal.