Analysis of Real Operation Conditions in Ringing and Tone Systems

For correct dimensioning of subscriber signalling systems knowledge of the real operation conditions is necessary. However, very little practical investigations have been done until now because of measuring difficulties. During the last years at Ericsson considerable efforts have been made to investigate how signal loads, levels and unwanted signal voltages depend upon the exchange design, the traffic and the subscribers´ behaviour. Measuring methods have been developed for the system analysis, among other things a microprocessor based equipment for continuous measuring, recording and evaluation of signalling Loads. This paper presents measuring results obtained in different countries and in different types of exchanges. The degree of usage of installed signalling power is defined and related to the degree of usage of the traffic-carrying devices of the exchange. Conclusions regarding the dimensioning of the signal outputs and their protection are given. Finally a brief description of Ericsson´s recently developed signalling equipment is presented.