Method of and apparatus for time-stabilization of sampling pulses

摘要

A method and a circuit arrangement for time stabilization of scanning pulses for the stroboscopic sampling of periodically recurring signals. Stroboscopic sampling is performed by means of scanning pulses having a repetition period slightly different from the period of the recurring signals to be scanned. The signals to be scanned are transmitted over a transmission line in which a measuring section of known length is defined by the distance between two tapping points to each of which a sampling circuit is connected. The signals transmitted over the transmission line are sampled stroboscopically by means of the scanning pulses whereby time-transformed signals are obtained. These time-transformed signals are separated by a time interval corresponding to the transit time of the signals in the measuring section multiplied by the time-transformation factor. The number of scans occurring in this time-interval is counted and compared with a given desired number; if there is a difference between the two compared numbers, the scanning pulse period is changed so as to eliminate this difference. In an alternative embodiment, the measuring section is defined by a transmission line section of different characteristic impedance, and the recurrent signals are sampled at a single tapping point ahead of this transmission line section; in this case the time-interval corresponding to the transit time is determined by means of the reflexions occurring at the impedance breaks.