Digital compass averaging circuit
AssigneeLaitram, L.L.C.
InventorJohn T. Fowler
Life of this patent
Estimating the term…
Abstract
For use with a remote reading magnetic compass a digital circuit for computing an output indication of compass heading to provide an output heading indication corrected for changes between successive compass readings. Compass heading is corrected in accordance with a weighted average value of the difference between successively read headings to provide an output which is representative of a true or weighted average heading and an output of the magnitude and sense of such difference.
Claims11
A signal averaging circuit comprising:
- means for receiving digital signals representing successive angular positions and for providing signal indications thereof;
- first means operative in response to a previously received digital signal for storing a representation of an average value thereof;
- second means operative to store said representation from said first storing means and thence operative in response to a presently received digital signal to effectively subtract the value of said present digital signal from the value of said previous digital signal;
- third means operative in response to the resultant of said subtraction to provide an output signal indication of the magnitude of the difference between the values of said previous and present digital signals and an output signal indication of the direction of said difference with respect to the previous angular position;
- and
- fourth means operative in response to the resultant of said subtraction to provide an output indication of an averaged value of said previous and present digital signals and of the corresponding average angular position.
For use with a digital magnetic compass providing digital signals representative of compass heading, circuitry for computing an average compass heading comprising:
- means for receiving said digital signal and including means for providing a signal indication of the commencement and termination of said digital signals;
- divider means operative to provide an output count which is a predetermined subdivision of an input count thereto and providing an output signal indication of the magnitude of the difference between the previous and present computed headings;
- first counter means for storing and a count representative of a previous computed compass heading and operative in response to signals from said divider means to provide an output count representative of an average between the previous and present computed headings;
- second counter means operative to store the count from said first counter means and thence operative in response to said digital signals representing a present compass heading to effectively subtract the value of said present heading from the count representing said previous computed heading;
- first gate means operative to selectively provide incrementing and decrementing control signals for said second counter means;
- second gate means operative to selectively provide incrementing and decrementing control of said first counter means and divider means and providing an output signal indication of the direction of said difference with respect to a previous computed compass heading;
- detector means operative in response to the resulting count in said second counter means representing a heading equal to or greater than 180.degree. to provide a signal indication to said first and second gate means;
- and
- oscillator means operative upon termination of said received digital signals to provide clock signals to said divider means and to said second counter means to cause said second counter means to cycle from said resulting count to a final value and to cause corresponding cycling of said divider means.
Dependencies are inferred from the claim text.