Timing means

Claim 2

Timing means comprising first means for deriving two signals dependent upon a variable angle theta , a first of said signals being representative of K cos theta and the second of K sin theta , where K is a variable factor, a signal generator for generating a third signal that increases progressively with time from a predetermined initial value, the signal generator being resettable to a condition in which the third signal is returned to said initial value to recommence increase with time therefrom, a signal integrator for accumulating an integral with respect to time in accordance with signals supplied thereto, second means responsive to the integral accumulated by the integrator for resetting the signal generator whenever the integral reaches a predetermined value whereby the period of each excursion of the third signal from the said predetermined initial value varies in accordance with the value K, signal-supply means for supplying the third signal to the integrator for integration thereby, and further signal-supply means for supplying the said first and second signals to the integrator for integration thereby in an opposite sense to the third signal, said further signal-supply means comprising first and second switches for supplying respectively the first and second signals to the integrator, each switch being switchable from one to another state to interrupt the supply of the respective signal to the integrator, means for switching the first switch from the said one state when the third signal attains a predetermined relationship with respect to the first signal, and means for switching the second switch from the said one state when the third signal attains the said predetermined relationship with respect to the second signal.

Claim 3

Timing means according to claim 1, comprising second and third integrators, an input terminal for receiving an input signal, third and fourth switches for supplying the said input signal to the said second and third integrators respectively for integration with respect to time thereby, each said third and fourth switch being switchable from one to the other of two states to interrupt the supply of the said input signal to the respective integrators, and means for coordinating switching of the third and fourth switches with the switching of said first and second switches respectively.

Claim 4

Timing means according to claim 2, comprising means for deriving fourth and fifth signals representative of the sense of the first and second signals respectively, said second and third integrators being responsive to the fourth and fifth signals respectively to vary the sense in which the said input signal is integrated thereby, whereby the sense in which the said input signal is integrated by the second and third integrators varies in accordance with the sense of K cos theta and K sin theta respectively.

Claim 5

Timing means according to claim 1, wherein the said signal generator includes an integrator for integrating a constant voltage with respect to time.

Claim 6

Navigation apparatus for a craft comprising means responsive to heading theta of the craft for deriving first and second signals representative respectively of K cos theta and K sin theta where K is a variable factor, a signal generator for generating a third signal that increases progressively with time from a predetermined initial value, the signal generator being resettable to a condition in which the third signal is returned to said initial value to recommence increase with time therefrom, a signal integrator for accumulating an integral with respect to time in accordance with signals supplied thereto, second means responsive to the integral accumulated by the integrator for resetting the signal generator whenever the integral reaches a predetermined value, signAl-supply means for supplying the third signal to the integrator for integration thereby, further signal-supply means for supplying the said first and second signals to the integrator for integration in an opposite sense to the third signal, said further signal-supply means comprising first and second switches for supplying respectively the first and second signals to the integrator, each switch being switchable from one to another state to interrupt the supply of the respective signal to the integrator, second and third integrators, means for providing a signal dependent upon craft-speed, means for supplying the said speed signal to the said second integrator only so long as said first switch remains in its said one state, means for supplying the said speed signal to the said third integrator only so long as said second switch remains in its said one state, means for switching the first switch from its said one state when the third signal attains a predetermined relationship with respect to the first signal, and means for switching the second switch from its said one state when the third signal attains the said predetermined relationship with respect to the second signal, whereby the integrals accumulated by the said second and third integrators are in accordance with components of the distance travelled by the craft.

Claim 7

Navigation apparatus for a craft comprising means responsive to heading theta of the craft for deriving first and second signals representative respectively of K cos theta and K sin theta where K is a variable factor, a signal generator for generating a third signal that increases progressively with time from a predetermined initial value, the signal generator being resettable to a condition in which the third signal is returned to said initial value to recommence increase with time therefrom, a signal integrator for accumulating an integral with respect to time in accordance with signals supplied thereto, second means responsive to the integral accumulated by the integrator for resetting the signal generator whenever the integral reaches a predetermined value, signAl-supply means for supplying the third signal to the integrator for integration thereby, further signal-supply means for supplying the said first and second signals to the integrator for integration in an opposite sense to the third signal, said further signal-supply means comprising first and second switches for supplying respectively the first and second signals to the integrator, each switch being switchable from one to another state to interrupt the supply of the respective signal to the integrator, second and third integrators, means for providing a signal dependent upon craft-speed, means for supplying the said speed signal to the said second integrator only so long as said first switch remains in its said one state, means for supplying the said speed signal to the said third integrator only so long as said second switch remains in its said one state, means for switching the first switch from its said one state when the third signal attains a predetermined relationship with respect to the first signal, and means for switching the second switch from its said one state when the third signal attains the said predetermined relationship with respect to the second signal, whereby the integrals accumulated by the said second and third integrators are in accordance with components of the distance travelled by the craft.

Claim 8

Navigation apparatus for use with a craft, comprising a plurality of first magnetic-detector devices spaced apart from one another for sensing the earth''s magnetic field as subjected to deviation by the craft, the said first magnetic-detector devices sensing respectively the magnitudes at their spaced locations of the component of the deviated field acting parallel to a first of two mutually inclined craft-axes, a plurality of second magnetic-detector devices spaced apart from one another for sensing respectively the magnitudes at their spaced locations of the component of the deviated field acting parallel to the second of the two axes, means for deriving from each said magnetic-detector device an electric signal in accordance with the magnitude of deviated-field component sensed by that individual device, first circuit means responsive to the signals derived from said first magnetic-detector devices to provide a signal in accordance with the component of undeviated field acting parallel to said first axis, second circuit means responsive to the signals derived from said second magnetic-detector devices to provide a signal in accordance with the component of undeviated field acting parallel to said second axis, variation-correction means responsive to the two component-signals provided by said first and second circuit means to derive therefrom two signals dependent on a variable angle theta and representative respectively of the said components of undeviated field corrected for local magnetic-variation, a first of said two signals being representative of K cos theta and the second of K sin theta , where K is a variable factor, a signal generator for generating a third signal that increases progressively with time from a predetermined initial value, the signal generator being resettable to a condition in which the third signal is returned to said initial value to recommence increase with time therefrom, a signal integrator for accumulating an integral with respect to time in accordance with signals supplied thereto, second means responsive to the integral accumulated by the integrator for resetting the signal generator whenever the integral reaches a predetermined value, signal-supply means for supplying the third signal to the integrator for integration thereby, further signal-supply means for supplying the said first and second signals to the integrator for integration in an opposite sense to the third signal, said further signal-supply means comprising first and second switches for supplying respectively the first and second signals to the integraTor, each switch being switchable from one to another state to interrupt the supply of the respective signal to the integrator, second and third integrators, speed-sensing means for providing a signal dependent upon speed of the craft, third and fourth switches for supply the said speed signal to the said second and third integrators respectively for integration with respect to time thereby, each of said third and fourth switches being switchable from one to another state to interrupt the supply of the said speed signal to the respective integrators, means for switching the first and third switches from their said one state when the third signal attains a predetermined relationship with respect to the first signal, means for switching the second and fourth switches from their said one state when the third signal attains the said predetermined relationship with respect to the second signal, and means for varying the senses with which the speed signal is integrated by said second and third integrators in accordance with the senses of the first and second signals respectively, whereby the integrals accumulated by the said second and third integrators are in accordance with components of the distance travelled by the craft along earth-defined axes.

Claim 9

Navigation apparatus for use with a craft, comprising a plurality of first magnetic-detector devices spaced apart from one another for sensing the earth''s magnetic field as subjected to deviation by the craft, the said first magnetic-detector devices sensing respectively the magnitudes at their spaced locations of the component of the deviated field acting parallel to a first of two mutually inclined craft-axes, a plurality of second magnetic-detector devices spaced apart from one another for sensing respectively the magnitudes at their spaced locations of the component of the deviated field acting parallel to the second of the two axes, means for deriving from each said magnetic-detector device an electric signal in accordance with the magnitude of deviated-field component sensed by that individual device, first circuit means responsive to the signals derived from said first magnetic-detector devices to provide a signal in accordance with the component of undeviated field acting parallel to said first axis, second circuit means responsive to the signals derived from said second magnetic-detector devices to provide a signal in accordance with the component of undeviated field acting parallel to said second axis, variation-correction means responsive to the two component-signals provided by said first and second circuit means to derive therefrom two signals dependent on a variable angle theta and representative respectively of the said components of undeviated field corrected for local magnetic-variation, a first of said two signals being representative of K cos theta and the second of K sin theta , where K is a variable factor, a signal generator for generating a third signal that increases progressively with time from a predetermined initial value, the signal generator being resettable to a condition in which the third signal is returned to said initial value to recommence increase with time therefrom, a signal integrator for accumulating an integral with respect to time in accordance with signals supplied thereto, second means responsive to the integral accumulated by the integrator for resetting the signal generator whenever the integral reaches a predetermined value, signal-supply means for supplying the third signal to the integrator for integration thereby, further signal-supply means for supplying the said first and second signals to the integrator for integration in an opposite sense to the third signal, said further signal-supply means comprising first and second switches for supplying respectively the first and second signals to the integraTor, each switch being switchable from one to another state to interrupt the supply of the respective signal to the integrator, second and third integrators, speed-sensing means for providing a signal dependent upon speed of the craft, third and fourth switches for supply the said speed signal to the said second and third integrators respectively for integration with respect to time thereby, each of said third and fourth switches being switchable from one to another state to interrupt the supply of the said speed signal to the respective integrators, means for switching the first and third switches from their said one state when the third signal attains a predetermined relationship with respect to the first signal, means for switching the second and fourth switches from their said one state when the third signal attains the said predetermined relationship with respect to the second signal, and means for varying the senses with which the speed signal is integrated by said second and third integrators in accordance with the senses of the first and second signals respectively, whereby the integrals accumulated by the said second and third integrators are in accordance with components of the distance travelled by the craft along earth-defined axes.