Patrick A Toole

US Patent:

61917214, Feb 20, 2001

Filed:

Nov 5, 1999

Appl. No.:

9/435000

Inventors:

Gregory M. Johnson - Goleta CA
John C. Baker - Santa Barbara CA
Daniel T. Zaida - Goleta CA
Patrick A. Toole - Santa Barbara CA

Assignee:

Litton Systems, Inc. - Woodland Hills CA

International Classification:

H03M 166

US Classification:

341147

Abstract:

A time based digital to analog converter is presented in which known reference voltages are used to create variable period waveforms which, when combined according to a desired computation, can convert digital words into a sinusoidal signal of a precision variable. To illustrate the application of the present invention, a hemispherical resonator gyroscope (HRG) operating in force rebalance is presented wherein a time based digital to analog converter with a variable period output controls the HRG electronics in nulling the standing wave. A rate of the standing wave is calculated, and a software component calculates the fraction of the maximum rate needed to oppose and null the initial rate of the standing wave. The fraction of the maximum rate is converted to digital words corresponding to the number of periods of a clock connected to the circuit. Using the digital words thus determined, a gate array using digital logic generates waveforms having variable periods, where the amplitude of the waveforms correspond to fixed reference voltage sources, and the period of the waveforms are determined by the digital words in the earlier calculation.