RECORD CARRIER AND APPARATUS FOR SCANNING THE RECORD CARRIER

摘要

A RECORD CARRIER (1) IS DESCRIBED COMPRISING A SERVO TRACK (4) INDICATING AN INFORMATION TRACK (9) INTENDED FOR RECORDING INFORMATION BLOCKS REPRESENTED BY MARKS HAVING LENGTHS EXPRESSED IN CHANNEL BITS, WHICH SERVO TRACK (4) HAS A PERIODIC VARIATION OF A PHYSICAL PARAMETER. THE PERIODIC VARIATION IS MODULATED FOR ENCODING RECORD CARRIER INFORMATION, SUCH AS ADDRESSES. THE MODULATION IS A BI-PHASE MODULATION IN WHICH A DATA BIT OF THE RECORD CARRIER INFORMATION IS ENCODED BY A FIRST PREDETERMINED NUMBER OF VARIATIONS OF FIRST PHASE FOLLOWED BY THE SAME NUMBER OF VARIATIONS OF A SECOND PHASE INVERSE TO THE FIRST PHASE. A RECORDING AND/OR PLAYBACK DEVICE HAS A DEMODULATOR FOR RETRIEVING DATA BITS OF THE RECORD CARRIER INFORMATION FROM A FIRST PREDETERMINED NUMBER OF VARIATIONS OF A FIRST PHASE FOLLOWED BY THE SAME NUMBER OF VARIATIONS OF A SECOND PHASE INVERSE TO THE FIRST PHASE.(FIGURE 2).