Method and arrangement for minimizing skew

Abstract

At a signal transmission rate of 1 Gb/s, the 'bit time' is 1 ns. This corresponds to a bit length in an optical fibre of 0.2 m. In view of the fact that skew shall not exceed one-tenth of a bit length, this means that length differences between different conductors in a transmission line may not exceed 2 cm. With the intention of minimizing the skew that would thus otherwise occur in a transmission line, the transmission line (1) and its conductors (2) have been joined to form a ribbon cable or flat cable where the length difference (5) between different conductors (2) in the transmission line does not exceed 2 cm. By providing transmission lines, such as rolled-up flat ribbon cables for instance, which have been previously cut to precise and appropriate lengths, such as lengths of 10, 20, 30 m for instance, with a largest length deviation between different conductors of .+-.1 cm, skew can be minimized when using the cables. By conductor is primarily meant an optical fiber, although other conductors such as coaxial conductors or twin wire conductors are conceivable. Since the three fibres are seated together along the major part of their lengths, they can be readily laid in an installation, which is an advantage in many types of installations, and the cable parts can be easily drawn apart and laid individually. With a guaranteed greatest length deviation of .+-.1 cm of each fibre, skew can be controlled and more reliable signal transmission made possible with the aid of a majority decision.