Wobble frequency

Optical discs with the exception of the DVD-RAM have their data encoded on a single spiral, or a groove, which covers the surface of the disc. In the case of recordable media, this spiral contains a slight sinusoidal deviation from a perfect spiral. The period of this sine curve corresponds to the wobble frequency. First of all, it is used as a synchronization source to achieve constant linear velocity while writing a disc. The frequencies quoted all assume that the disc is being written at the 'x1' speed. The frequencies are appropriately higher for faster writing speeds.