As implemented on LaserDiscs, Dolby Digital audio employs the Dolby Laboratories AC-3 lossy compression technique to encode five full-range audio channels and one Low Frequency Effects channel at a data rate of 384 thousand bits per second. The bitstream is then modulated by Quadrature Phase-Shift Keying onto a carrier wave which displaces analog audio channel 2/R. This carrier wave must then be passed, via a special RF output, to a suitable external decoder to permit recovery of the audio information; attempting to play it back via the onboard FM decoder will result in an unmeaning hiss. This system cannot be applied to PAL discs for technical reasons.