Abstract: A system having a medium which presents signal sequences which at least partly consist of binary signal sequences and a device for generating a synchronization signal for synchronizing at least parts of said signal sequence (blocks, words). A binary signal sequence contains a synchronization pattern which consists of (2N+1) groups of codes of m+n bits. A number of (N+1) groups have a code content which exhibits a given, at least minimum Hamming distance with respect to the code (codes) of the other group (groups). The device includes a majority decision device which produces the synchronization signal by means of the n bit codes of said (2N+1) groups on the basis of a majority decision (N+1 out of 2N+1).

Abstract: The invention relates to a method of demodulating a quadphase coded data signal and a receiver for carrying out the method. The quadphase code comprises four elementary wave forms, each wave form representing two bits of the original non-coded binary signal. An elementary wave form consists of four half bit intervals, the signal corresponding to the first and the second bit, respectively, being transmitted in the first and the second half bit interval and the signal corresponding to the inverted value of the first and the second bit, respectively, being transmitted in the third and the fourth half bit interval. In a receiver according to the invention such a signal is sampled in each of the four half bit intervals. In principle all information is already available after the sampling operations in the first and the second half bit interval, but by utilizing all four samples a proper protection from noise, interference and zero level shifts is obtained.

Abstract: A disc-shaped record carrier having an information track which is divided into a plurality of sectors per track circumference. Each sector is divided into a data section, in which the data can be recorded, and a synchronizing section. This synchronizing section consists of an optically detectable relief structure and comprises an indicator portion and an address portion. The address portion contains the information about the track number and the sector number. The indicator portion serves to define the beginning of the address portion unambiguously and for this purpose has such a relief structure that the indicator signal produced after cooperation with the radiation beam has a frequency which is clearly distinguishable from signal components resulting from the address portion.