NAVIGATION SATELLITE SYSTEM EMPLOYING TIME SYNCHRONIZATION

• US 3,643,259 A
• Filed: 02/20/1970
• Issued: 02/15/1972
• Est. Priority Date: 02/20/1970
• Status: Expired due to Term

• Current Assignee: Ronald S. Entner
• Original Assignee: Ronald S. Entner
• Inventors: Entner, Ronald S.
• Primary Examiner(s): Borchelt, Benjamin A.
• Assistant Examiner(s): Berger, Richard E.
• Application Number:
  US05/015,824
• Time in Patent Office: 725 Days
• Field of Search: 343/112D,112,1ST 235/150.271,150.27
• US Class Current: 342/357.21
• CPC Class Codes: G01S 11/08 using synchronised clocks
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A system to navigate aircraft employing an earth satellite emitting stored signals from its memory device at predetermined times, controlled by a precision clock. The aircraft desiring navigation aid, having an atomic clock synchronized with the satellite'"'"''"'"'s, can thus calculate the propagation delay and the distance travelled by the signal. A computer aboard the aircraft generates a mathematical representation of a sphere, the radius being equal to the distance travelled by the satellite signal. Employing an inertial navigation set linked to the computer, the computer generates two additional spheres, each displaced from the previous sphere by the distance the aircraft travelled prior to receiving the succeeding satellite transmission. The intersection point of the three spheres is the location of the satellite. Knowing the satellite trajectory in advance, the aircraft can thus determine its position with respect to the earth.

Claims

1. A method for locating the position of a craft comprising the steps of:

placing a satellite provided with a receiver, transmitter, clock and a memory device into earth orbit;

transmitting to said satellite receiver the satellite'"'"''"'"'s present and future position;

storing said transmission in said memory device;

transmitting said stored transmission at predetermined intervals determined by said clock;

receiving said satellite transmissions aboard said craft, said craft having a clock synchronized with said satellite clock;

calculating the distance said transmission covers in the time between the predetermined times of transmissions and its reception by said craft;

calculating the distance said craft travels between satellite transmissions;

developing from said satellite transmissions three simultaneous equations based upon the distances the satellite transmissions and craft travelled; and

simultaneously solving said equations, the solution for said simultaneous equation determining the position of said satellite, whereby the position of said craft may be determined.

2. A navigation system for a craft comprising:

a space-borne satellite;

means for transmitting from said satellite the position of said satellite at predetermined intervals;

means aboard said craft for receiving said transmissions;

means aboard said craft for calculating the distance said transmission travelled before reception aboard said craft;

means for determining the distance said craft travels between succeeding transmissions from said satellite; and

computer means aboard said craft for calculating the position of said craft relative to said satellite based on said calculating means and said determining means.

3. A navigation system as recited in claim 2 wherein said determining means comprises an inertial navigation set.

4. A navigation system as recited in claim 3 wherein said space-borne satellite includes:

a receiver for receiving information regarding the satellites orbit; and

a memory device for storing said received information.

5. A navigation system as recited in claim 4 wherein said transmitting means comprises:

a transmitting antenna; and

a precision clock for pulsing said stored information for transmission through said transmitting antenna.

6. A navigation system as recited in claim 5 wherein said craft includes a precision clock synchronized with said satellite precision clock;

and said calculating means calculates the distance said transmission covered based on the time elapsed from transmission until reception by said receiving means.

7. A navigation system as recited in claim 6 wherein said computer means generates three spheres on reception of three satellite signals by said craft, said satellite on each sphere'"'"''"'"'s surface, said craft at the centroid of each sphere, the radius of each sphere representing the distance calculated by the calculating means, the distance between centroids of the spheres being determined by said inertial navigation set, the intersection of said three spheres determining the position of said satellite.