Patent ID: 7489258
Filing Date: 2009-02-10
Classification: G11B

Abstract:
1. Device for embedding a secondary signal of a secondary channel in the primary data bit stream of a primary channel, wherein said primary data bit stream comprises a number of recording frames ( 12 ) each starting with a frame sync followed by a number of DC-control blocks each including a number of primary data bits and a DC-control bit and wherein said primary data bit stream with embedded secondary signal shall be modulation encoded, in particular by a 17PP modulation encoder ( 4 ), using a first or a second modulation table, wherein the second modulation table is used only for modulation encoding of predetermined combinations of the last bits of a recording frame, and wherein the first bit of a frame sync indicates which modulation table has been used for modulation encoding of the last bits of the previous recording frame, said device comprising: a check unit ( a setting unit ( a) in a first case, where said check results in different polarities, the last DC-control bit of the first recording frame to a bit value controlled by the bit value of a secondary bit of said secondary signal to be embedded resulting in a polarity of the frame sync of the second recording frame representing the bit value of said secondary bit, or b) in a second case, where said check results in identical polarities, the second last DC-control bit of the first recording frame or the first bit of the frame sync of the second recording frame to a bit value controlled by the bit value of said secondary bit.