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Laser Power Calibration Method for Pulse Width Modulation Optical Recording

IP.com Disclosure Number: IPCOM000111128D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Elser, KA: AUTHOR

Abstract

Power calibration for Pulse Width Modulation (PWM) recording requires that the smallest mark (a circular mark) have a sensed mark length of exactly d times T where d is the shortest length run in a

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Laser Power Calibration Method for Pulse Width Modulation Optical
Recording

      Power calibration for Pulse Width Modulation (PWM) recording
requires that the smallest mark (a circular mark) have a sensed mark
length of exactly d times T where d is the shortest length run in a

(d,k) Run Length Limited (RLL) code and T is the channel code bit
clock period.  The problem to be solved is "What method does one use
to set the power?"

      The method is to write a tone with a frequency of 3*d/2 for a
(d,k) RLL code and adjust the power such that the peak to peak
amplitude of the tone is maximized.  Fig. 1 shows a regular 3T tone
(solid lines) and the calibration tone (dotted lines) for the (1,k),
top, and (2,k), bottom, RLL codes.