Digital discriminator for determining frequency error of an oscillator
AssigneeSperry Corporation
InventorsHenry C. Johnson, Ronald W. Kipp
Life of this patent
Estimating the term…
Abstract
An adjustable alternating signal having a desired period, P, is applied to a cycle counter arranged to count n cycles and applied to a timer arranged to time out n.multidot.P after a first cycle is applied to the counter and timer. A comparator is coupled to the counter and timer to determine whether the counter reaches its count of n cycles first or whether the timer times out first indicating that the period of the alternating signal is shorter or longer, respectively, than desired. An integrator is responsive to the signal from the comparator for changing the alternating signal which achieves the desired period.
Claims10
A digital discriminator coupled to receive an alternating signal from an adjustable alternating signal source, said alternating signal being adjustable about a desired period, for providing a signal indicative of variations from the desired period comprising:
- means coupled to receive a sequence of pulses including a first pulse, each pulse representing a period of said alternating signal for counting n successive pulses in said sequence and for providing a first signal at a time after reception of n said pulses, n being an integer greater than 1;
- means responsive to said first pulse of said sequence for providing a second signal at a predetermined time thereafter, said predetermined time being substantially equal to n said desired periods;
- means responsive to said first signal and said second signal for providing a third signal indicative of which of said first and second signals occurs first and thereby indicating whether said alternating signal period is shorter or longer than said desired period;
- and
- means coupled to said alternating signal source and responsive to said third signal for adjusting said alternating signal period in a direction to substantially achieve said desired period.
Dependencies are inferred from the claim text.