Planning of mixed analogue-digital circuits (chains, connections)
发布日期
1993-03-01
标准状态
现行有效;
摘要
In the period of transition from a fully analogue to a fully digital network, mixed analogue-digital circuits, chains and connections will take place on international and national networks for a fairly prolonged time.
The definition of notions of “mixed circuits, chains and connections” and examples of their possible structures are given in Annex A.
Structure of mixed circuits and moreover that of connections and chains, may be highly complex in comparison with circuits, chains and connections composed of transmission systems of one type (analogue or digital), that is, of homogeneous structure. The most favourable from the point of view of minimization of analogue-digital conversions is “overlay” strategy. Distortions and noise in mixed circuits to a great extent differ from those in circuits of the homogeneous structure, because in the case of mixed circuits distortions and noise typical for both analogue and digital transmission systems are combined taking into account the influence made on them by analogue-digital conversions. Measuring methods for distortions and noise in mixed circuits are of specific character as well. Factors mentioned above make the maintenance and operation of mixed circuits more complicated. Thus the task of developing planning rules for mixed circuits (chains, connections) becomes actual as well as studying the addition laws for distortions and noise.
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发表于 2008-10-17 10:42:17
