U.S. Philips Corporation

Martijn H Hofelt

Albert M Rijckaert

Edmond De Niet

For a controlled positioning of a read element relative to a track to be read during the read-out of such a record carrier, low-frequency tracking signals may be recorded in the tracks. Instead of adding separate tracking signals to the information signal, these tracking signals are represented by the d.c. content of the information signal. During conversion of the information words of the information signal into channel words steps are therefore taken to provide two channel words whose d.c. content is equal but opposite for each information word. The choice between these two channel words is made depending on a control signal which depends on the desired tracking signal.

Method and apparatus for recording a digital information signal

A system for quantizing signals having a transmitter section and a receiver section interconnected by a transmission path. The transmitter section includes a quantizer, a difference producer, and a filter. An input signal is differenced with a feedback signal, filtered and quantized to produce a first quantized output signal. The first quantized output signal is filtered to produce the feedback signal. The filtered difference signal is further differenced with the quantized output signal to produce a second difference signal which is quantized to produce a second quantized output signal containing the quantizing noise of the first quantized output signal. In the receiver section a first received signal (proportional to the first quantized output signal) is summed with a second received signal (proportional to the second quantized output signal) to produce a sum signal. The first received signal and the sum signal are each filtered and summed to produce a receiver output signal substantially free of quantizing noise.

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Eindhoven, Netherlands

Martijn H Hofelt