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Title: Area navigation system
Claims: We claim: 1. An area navigation system comprising: first means for receiving station-to-aircraft vector angle signals; processing means including averaging means coupled to said first receiving means for averaging said vector signals, and lag compensation means coupled to said averaging means, said lag compensation means, including means responsive to the amount of phase lag introduced by said averaging means for adjusting the degree of lag compensation; second means for receiving station-to-aircraft magnitude signals; a waypoint-to-aircraft vector computer having said signals from said processing means and said second receiving means coupled thereto; a station-to-waypoint vector generator, also coupled to said computer, to produce an electrical output signal representative of the corresponding waypoint-to-aircraft vector; and means coupled to said computer output signal for developing a display of the value of said aircraft-to-waypoint vector. 2. Apparatus as defined in claim 1 wherein said station-to-aircraft vector angle signal is a periodic variable phase electrical signal; and wherein said processing means includes means to develop a periodic phase reference signal, means to generate a voltage analog of the aircraft-to-station vector phase angle relative to said reference phase, means coupling said voltage analog as an input to said averaging circuit, and means coupled to the output of said lag compensation circuit to generate a periodic output signal having a phase equal to the average value of said variable phase signal relative to said reference phase. 3. Apparatus as defined in claim 2 further including limit sensing means defining an acceptable range for said voltage analog and means responsive to said voltage being outside the acceptable range to effect a predetermined phase shift of said phase reference signal. 4. Apparatus as defined in claim 2 wherein said voltage analog generator comprises means for sensing a predetermined phase angle of said variable phase signal, and sample and hold means responsive to said predetermined phase to sample and store the value of said reference phase signal at that time. 5. Apparatus as defined in claim 4 wherein said variable phase signal is in the form of a square wave, and wherein said sample and hold means is responsive to the high to low transition of each square wave cycle. 6. Apparatus as defined in claim 5 wherein said reference phase signal is a ramp at the same frequency as said variable phase signal. 7. Apparatus as defined in claim 6 wherein said stationto-aircraft vector angle information includes a first periodic signal component of fixed frequency and constant phase, and a second periodic signal component of the same frequency, and of variable phase relative to said first component, means responsive to said first component to generate a first clock signal at said fixed frequency; and wherein said means for generating said reference ramp comprises a DC signal source, means to integrate said DC signal, means to reset said integrator, and means responsive to a predetermined phase angle of each cycle of said first clock signal to operate said integrator reset means. 8. Apparatus as defined in claim 7 wherein said first clock signal is a square wave, and wherein said means for operating said integrator reset means is responsive to a level transition of said clock square wave. 9. Apparatus as defined in claim 8 further including means to select which of said square wave level transitions operates said integrator reset means. 10. Apparatus as defined in claim 9 wherein said transition selection means comprises means to establish a particular transition to reset said integrator, limit sensing means for establishing an acceptable range for said voltage analog signal, and means responsive to said voltage analog signal being outside the acceptable range for changing the transition on which the ramp is reset. 11. Apparatus as defined in claim 7 further including limit sensing means for establishing an acceptable range for said phase angle voltage analog, and means responsive to said voltage analog being outside the acceptable range for changing the predetermined phase angle at which said integrator reset means is operated. 12. Apparatus as defined in claim 11 wherein said integrator reset phase angle is changed by 180.degree. . 13. Apparatus as defined in claim 7 wherein said means for generating said periodic output signal comprises means for comparing the output of said lag compensation circuit with said ramp signal to generate a pulse signal having a transition representative of the time that the two signals are equal, and means responsive to said transition for generating a periodic signal having the same frequency as said first clock signal, and having its zero phase coincident with said transition. 14. Apparatus as defined in claim 13 wherein said means for generating said output periodic signal comprises a counter, means for resetting said counter coincident with said transition, means for driving said counter at a second clock frequency such that a predetermined number of counts equals the period of said first clock signal, and means responsive to half said predetermined number of counts for turning off said counter. 15. Apparatus as defined in claim 2 wherein said averaging circuit comprises a low pass filter having a time constant in excess of about 10 seconds. 16. In an area navigation system comprising; first means for receiving station-to-aircraft vector angle signals; second means for receiving station-to-aircraft magnitude signals; a waypoint-to-aircraft vector computer having said signals from said second receiving means coupled thereto; a station-to-waypoint vector generator, also coupled to said computer, to produce an electrical signal representative of the corresponding waypoint-to-aircraft vector; the improvement comprising: a distance generator coupled to the output of said computer for developing a distance display signal, an angle generator coupled to the output of said computer for developing an angle display signal, a meter for displaying said angle and deviation from a selected track to waypoint signal, and sensitivity adjustment means responsive to said distance signal for reducing the sensitivity of said meter as said distance signal becomes smaller. 17. Apparatus as defined in claim 16 wherein said sensitivity control means includes means for establishing a threshold value for said difference signal, means for establishing a normal meter sensitivity, and means responsive to said distance signal being less than said threshold level for reducing said meter sensitivity below its normal level. 18. Apparatus as defined in claim 16 including digital display means, and means for selectively coupling said distance signal and said angle signal to said display means. Other info: Inventors: Foster, George B. (Worthington, OH, US) Gibbs, Paul Douglas (Blacklick, OH, US) Application Number: 476513 Filing Date: 1974-06-05 Publication_date: 1978-01-17 Assignee: Air Data, Inc. (Worthington, OH) Primary Class(es): 701/206 342/49, 342/399, 342/404, 701/218, 702/92 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Gruber, Felix D. Assistant Examiner: Attorney: Cennamo; Anthony D. |
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