A rotational frequency measurement circuit, comprising: a counter configured to count clock cycles of a clock signal during a measurement interval, the measurement interval being a preselected time interval, the counter operable to output a count value upon receipt of a pulse, the pulse corresponding to at least one of several protrusions on a rotary component of a rotating machine, the count value representing the number of clock cycles that have passed since a start of the measurement interval; a memory coupled to the counter and configured to receive a plurality of count values from the counter during the measurement interval, the memory operable to store each count value separately and sequentially during the measurement interval; and a frequency processor coupled to the memory, the frequency processor operable to determine a rotational frequency of the rotary component using a difference between a most-recent count value and a selected previous count value and a window of measurement, the window of measurement representing the number of pulses that have occurred between the most-recent count value and the selected previous count value during the measurement interval; characterized in that the frequency processor is further operable to slide the window of measurement to a next most-recent count value and a next selected previous count value in the memory, such that the most-recent count value is included in said sliding window of measurement, and determine the rotational frequency of the rotary component using a difference between the next most-recent count value and the next selected previous count value and the window of measurement. a counter configured to count clock cycles of a clock signal during a measurement interval, the measurement interval being a preselected time interval, the counter operable to output a count value upon receipt of a pulse, the pulse corresponding to at least one of several protrusions on a rotary component of a rotating machine, the count value representing the number of clock cycles that have passed since a start of the measurement interval; a memory coupled to the counter and configured to receive a plurality of count values from the counter during the measurement interval, the memory operable to store each count value separately and sequentially during the measurement interval; and a frequency processor coupled to the memory, the frequency processor operable to determine a rotational frequency of the rotary component using a difference between a most-recent count value and a selected previous count value and a window of measurement, the window of measurement representing the number of pulses that have occurred between the most-recent count value and the selected previous count value during the measurement interval; characterized in that the frequency processor is further operable to slide the window of measurement to a next most-recent count value and a next selected previous count value in the memory, such that the most-recent count value is included in said sliding window of measurement, and determine the rotational frequency of the rotary component using a difference between the next most-recent count value and the next selected previous count value and the window of measurement.