Browse Prior Art Database

Method of Obtaining Greater than 99 Power Calibrations in CD-R Drives

IP.com Disclosure Number: IPCOM000118183D
Original Publication Date: 1996-Oct-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Asthana, P: AUTHOR

Abstract

Currently, Compact Disk-Recordable (CD-R) drives are limited to 99 power calibration steps. In the past, this has not been a problem as prior CD-R drives have only been able to write a maximum of 99 separate times (up to 99 tracks). With the recent advent of packet recording, the number of possible separate writes to a CD-R disk has increased substantially beyond 99. However, the Power Calibration Area (PCA) of all CD-R disks still only as enough space allocated for 99 power calibrations. Thus, any packets recorded beyond the 99th will be without the benefit of power calibration, which means that non-optimal powers may be used to record.

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Method of Obtaining Greater than 99 Power Calibrations in CD-R Drives

      Currently, Compact Disk-Recordable (CD-R) drives are limited to
99 power calibration steps.  In the past, this has not been a problem
as prior CD-R drives have only been able to write a maximum of 99
separate times (up to 99 tracks).  With the recent advent of packet
recording, the number of possible separate writes to a CD-R disk has
increased substantially beyond 99.  However, the Power Calibration
Area (PCA) of all CD-R disks still only as enough space allocated for
99 power calibrations.  Thus, any packets recorded beyond the 99th
will be without the benefit of power calibration, which means that
non-optimal powers may be used to record.

      One solution to the problem is to increase the length of the
PCA area to allow for a greater number of calibrations.  This is not
a preferred solution; however, one difficulty with this approach is
determining the optimal amount of space to allocate (i.e., 300
writes, 999 writes, 5000 writes?).  A second problem is that a large
number of  pieces of CD-R media already exist with the current
standard length of  PCA region.

      The solution proposed in this disclosure is an algorithm to do
the power calibration on the data tracks as needed.  Implementation
of the algorithm will require modification of the microcode of packet
enabled CD-R drives.  The algorithm is as follows:
  1.  If <99 power calibrations have been done on the disk,
       continue to use the existing PCA to obtain appropriate
       write power values (including the alpha and beta used
       in drives with active power control).
  2.  If the PCA is used up, start the write process by first
       writing a 'write calibration packet' in the next recordable
       data region. The write calibration packet would consist of...