VERFAHREN UND AUSRÜSTUNG ZUR REDUZIERUNG VON PHASENSPRÜNGEN BEIM UMSCHALTEN ZWISCHEN SYNKRONISATIONSQUELLEN

A method and an arrangment for reducing phase jumps in a frame synchronization signal when switching between synchronization signal when switching between synchronization reference sources are disclosed. A new reference signal to which each of the two reference sources (signals) are phase locked, and has frequency n times the respective reference signal, is generated. A selection signal selects the new reference signal to be used, and the selected one is then divided back to its original frequency creating an input signal to a phase-locked loop generating the resulting frame synchronization signal. In this way, the maximum phase jumps are reduced from one period of the original reference signals to one period of the new reference signal. The invention is particularly applicable for reducing phase jumps on a master frame synchronization signal in a PDH system.