Repeat Audio

8-PSK Modulation

GPRS and HSCSD work with the normal GSM modulation scheme which is GMSK. GMSK has a lot of advantages, the most important of which being that it does not contain any amplitude modulation. However, its inherent low speed is the one big disadvantage. In GMSK, only 1 bit can be transmitted per symbol as opposed to e.g. 8-PSK where 3 bits are transmitted per symbol. As highlighted in the animation, this makes 8-PSK three times faster than GMSK.