Granted Patent B2

US 7,593,300 · App. 09/950,393 · Granted Sep 22, 2009

Abstract

Claims (9)

1. A method of detecting an off-format condition, comprising:

processing analog optical sensor signals to form digital versions of the analog signals;

forming, in a digital signal processor; a digital tracking error signal from the digital versions;

processing the digital tracking error signal in the digital signal processor using a tracking servo algorithm to form a tracking control signal;

low-pass filtering the tracking control signal;

detecting a DC level in the low-pass filtered tracking control signal over a threshold level; and

indicating the off-format condition if the DC level is above the threshold level over a period of time.

2. The method of claim 1 , further including indicating that tracking is not closed when the off-format condition is detected.

3. The method of claim 1 , wherein low-pass filtering includes integration.

Assignments (10)