The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 22, 1983
Filed:
Apr. 14, 1980
U.S. Philips Corporation, New York, NY (US);
Abstract
Disclosed is a record carrier for storage of digital data which is provided with a first periodic track variation having a period corresponding to a frequency at which the power spectrum of the digital signals is at a zero level. The first track variation produces a corresponding modulation of the radiation when scanned by a beam so that a clock signal can be derived from the detected radiation for synchronizing readout or recording of the data. The record carrier is further provided with a second periodic track variation in a direction transverse to the track direction having a period of the same order of magnitude, and preferably equal to the period of the first periodic track modulation. The second track variation produces a corresponding modulation of the beam which is detected and is used to generate to a tracking signal, the clock signal being used as phase reference signal for demodulation of the tracking signal. If the periods of the two track variations are equal, low-pass filtering automatically yields the tracking signal.