Device for determining periodic components of an alternating signal.

摘要

A device for sensing the frequency of an alternating electrical input signal. An autocorrelator (AC) at an input to the device generates a signal having a periodic component of frequency equal to four times the frequency of any periodic component in the input signal. The amplitude of non-periodic components is substantially reduced. The autocorrelator (AC) is followed by a series of sixteen frequency dividers (FD) whose outputs are applied to respective comparators (GC). Within each comparator (GC) the signal from a divider is compared with one of sixteen window signals, each representing a predetermined range of periods. Any output from the comparator (GC) is converted to a binary decimal form and is applied to a qualifier circuit (QC). The qualifier circuit only gives an output if at least eleven of the last eighteen signals applied thereto have represented a signal whose period lies within the same one of the predetermined ranges of periods.