Siemens-albis, Ag

Daniel Rieder

Alfred Lauper

Hanspeter Kupfer

A frequency synthesizing device generates periodic electrical oscillations of a frequency that can be arbitrarily determined, in which, after changing the frequency and resetting it to any desired value that has previously been generated, phase coherence is maintained. In addition to the elements of a direct digital frequency synthesizing device, the arrangement according to the invention has a time measuring unit (ZME) and a control logic (SL). The time measuring unit (ZME) periodically counts through a time interval from t=0 to t=t.sub.z and transmits the count status or a time signal to the computing system (R). The frequencies f.sub.i to be emitted and the time interval from t=0 to t=t.sub.z are chosen in such a manner that the phases of all the frequencies f.sub.i take on a constant value at the time t=0. This makes it possible to compute the coherent starting phase .phi..sub.N, so that the new frequency f.sub.N can be generated, with phase coherence, as of the time t.sub.N, even after one or more changes of frequency.

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Birmensdorf, Switzerland

Daniel Rieder