Marconi Instruments Limited

Damer Evelyn Waddington

Apparatus for use in extracting clock signals from a digital data stream that periodically generates an enable window of chosen duration at periods when a data edge is expected in the stream as disclosed. If a data edge is received during a window, the apparatus of this invention resets and restarts a clock pulse generator operating at the nominal frequency of the clock to be extracted. The extracted clock remains in synchronism with that of the data and is unaffected by noise spikes occuring outside the window area. If a chosen period of time elapses without any data edges received then the apparatus of this invention increases the window period so as to allow for jitter in the clock rate.

Electrical apparatus

A control device which is suitable for use with electronic apparatus is used to scan a range of signal or data values, such as a frequency spectrum, and to cease scanning when a selected parameter is found. The scanning operation is driven by a d.c. ironless motor which, once it has been initially spun by hand, continues to rotate until the selected parameter is detected.

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St. Albans, United Kingdom

Damer Evelyn Waddington