Dither signal remover for a dithered ring laser angular rate sensor utilizing an adaptive digital filter

A dithered angular rate sensor comprising:

• means for generating counter-propagating waves along a closed-loop path, each of said waves having a frequency related to the rotation of said sensor;
• means for dithering the frequency of at least one of said waves;
• first means responsive to said dithering for producing a dither reference signal D related to said dithering;
• readout means responsive to said waves for producing a readout signal R representative of the rotation of said sensor, said readout signal including a dither signal component due to said dithering;
• second means for producing a corrected sensor output signal G, where signal G is the difference between said readout signal R and a dither correction signal Y;
• mean or concurrently sampling said signals R, D, and G at discrete sample times;
• means for storing an array of N discrete numerical representations of the value of said signal D corresponding to N successive ones of said discrete sample times;
• third means for calculating a plurality of N-filter-weights W.sub.i as a function of the last sample signal G and selected ones of said array of numerical representations of signal D;
• and
• fourth means for calculating said correction signal Y as a function of said N-filter-weights and said array of numerical representations of said signal D.

A dithered angular rate sensor comprising:

• means for generating counter-propagating waves along a closed-loop path, each of said waves having a frequency related to the rotation of said sensor;
• means for dithering the frequency of at least one of said waves;
• first means responsive to said dithering for producing an analog dither reference signal related to said dithering;
• readout means responsive to said waves for producing a readout signal R representative of the rotation of said sensor, said readout signal including a dither signal component due to said dithering;
• second means for producing a corrected sensor output signal G, where signal G is the difference between said readout signal R and a correction output signal Y;
• means for converting said analog dither reference signal to a digital dither reference signal;
• adaptive digital filter means utilizing a plurality of filter-weights for operating on a plurality of discrete values of said digital dither reference signal occurring at discrete sample times to provide a dither correction signal Y;
• and
• means for providing said digital filter with filter-weights calculated as a function of selected past values of said dither reference signal and at least a selected one of past values of said corrected sensor output signal.

A dithered angular rate sensor comprising:

• means for generating counter-propagating waves along a closed-loop path, each of said waves having a frequency related to the rotation of said sensor;
• means for dithering the frequency of at least one of said waves;
• first means responsive to said dithering for producing an analog dither reference signal related to said dithering;
• readout means responsive to said waves for producing a readout signal R representative of the rotation of said sensor, said readout signal including a dither signal component due to said dithering;
• second means for producing a corrected sensor output signal G, where signal G is the difference between said readout signal R and a correction output signal Y;
• means for converting said analog dither reference signal to a digital dither reference signal;
• adaptive digital filter means utilizing at least one filter-weight for operating on at least one discrete value of said digital dither reference signal occurring at a discrete sample time to provide a dither correction signal Y;
• and
• means for providing said digital filter with filter-weights calculated as a function of at least one selected past value of said dither reference signal and at least a selected one of past values of said corrected sensor output signal.