Method deriving a quality signal from a read signal, and reading and

Abstract

Method of deriving a quality signal for a binary read signal having bit cells of constant length, and reading and recording devices which employ that method. During a reading process, an information pattern of optically detectable effects, representing certain of the bit cells, is scanned. A read signal is generated therefrom in which first read signal portions that exceed a reference value correspond to the effects. The quality signal is derived (in an analysis circuit) from the first read signal portions based on a measure of the deviation of first read signal portions corresponding to a particular length or mutual differences between length deviation of first read signal portions of different lengths. The quality signal can be used for adapting a recording strategy used in the recording of information, or for setting an equalizing filter. In the latter, in dependence on the quality signal, the ratio of the filter is set between a gain factor in a certain frequency range in the frequency band of the filter and a gain factor outside that frequency range.