Systems and methods to compensate a frequency

Abstract

A satellite vehicle compensation system ( 100 ) predicts the motion of two satellite vehicles and enhances the predictions with real-time updates of one or both of the vehicles. Using feedback loops ( 132, 134 ), the differences between the prediction and the actual motions are looped back to improve the accuracy of the motion predictor.A communications system includes a first communications node and a second communications node. A transmission frequency and/or a receiving frequency is compensated based on a predicted relative motion between the first and second communications nodes. The predicted relative motion is based on a first signal that is representative of a predicted motion of the first communications node and a second signal that is representative of a predicted motion of the second communications node. Real- time information may be used to minimize an error between predicted and measured motions of the first and/or second communications node.

1. In a satellite communications system involving a satellite vehicle SV 1  and a second satellite vehicle SV 2  moving relative to one another, a method for compensating at least one of a transmission frequency associated with SV 1  and a received frequency associated with SV 2 , the method comprising the steps of:
 predicting a motion of satellite vehicle SV 1  and generating a first output signal representative of the predicted motion of satellite vehicle SV 1 ;  
 predicting a motion of satellite vehicle SV 2  and generating a second output signal representative of the predicted motion of satellite vehicle SV 2 ;  
 supplying said first output signal and said second output signal to a processor and computing in said processor at least one of a compensating transmission frequency and a compensated receiving frequency based on said first output signal and said second output signal;  
 determining an actual motion of SV 1  and generating a third output signal representative of the actual motion of SV 1 ;  
 determining an actual motion of SV 2  and generating a fourth output signal representative of the actual motion of SV 2 ;  
 supplying said first output signal and said third output signal to a first summing junction and generating a first feedback signal representative of the difference between said first output signal and said third output signal;  
 supplying said second output signal and said fourth output signal to a second summing junction and generating a second feedback signal representative of the difference between said second output signal and said fourth output signal;  
 using said first feedback signal to improve the accuracy of said first output signal; and  
 using said second feedback signal to improve the accuracy of said second output signal.  
 
     
     
       2. A method of compensating a frequency associated with a first communications node or a second communications node in a communications system, comprising:
   generating a first signal representing a predicted motion of said first communications node;        generating a second signal representing a predicted motion of said second communications node;        computing at least one of a compensated transmission frequency or a compensated receiving frequency based on a predicted relative motion between said first and second communications nodes, wherein said predicted relative motion is based on said first and second signals;        generating a third signal representing an actual motion of said first communications node;        generating a feedback signal representing a difference between said first signal and said third signal; and        applying said feedback signal to improve accuracy of said first signal.     
     
     
       3. The method of  claim 2 , wherein said generating a first signal comprises:
   utilizing a static or dynamic flight plan associated with said first communications node to generate said first signal.     
     
     
       4. The method of  claim 3 , wherein said static or dynamic flight plan includes information relating to acceleration. 
     
     
       5. The method of  claim 3 , wherein said static or dynamic flight plan includes information relating to trajectory. 
     
     
       6. The method of  claim 3 , wherein said static or dynamic flight plan includes information relating to speed. 
     
     
       7. The method of  claim 3 , wherein said static or dynamic flight plan includes information relating to position. 
     
     
       8. The method of  claim 2 , wherein said generating a second signal comprises:
   receiving a real - time update including ephemeris data associated with at least one of said first communications node or said second communications node to generate said second signal.     
     
     
       9. A communications system that compensates a frequency associated with a first communications node or a second communications node, comprising:
   a motion predictor configured to provide a first signal representing a predicted motion of said communications node;        a data block configured to provide a second signal representing an actual motion of said first communications node;        an element configured to adjust said first signal based on a difference between said first and second signals; and        a processor configured to compute at least one of a compensated transmission frequency or a compensated receiving frequency based on a predicted relative motion between said first and second communications nodes;        wherein said predicted relative motion is based on said first signal and a third signal that is representative of a predicted motion of said second communications node.     
     
     
       10. The communications system of  claim 9 , wherein at least one of said first or second communications nodes is stationary. 
     
     
       11. The communications system of  claim 9 , wherein at least one of said first or second communications nodes is mobile. 
     
     
       12. The communications system of  claim 9 , wherein at least one of said first or second communications nodes is airborne. 
     
     
       13. The communications system of  claim 9 , wherein at least one of said first or second communications nodes is space- based.   
     
     
       14. The communications system of  claim 9 , wherein said data block is configured to provide real- time updates that include ephemeris data associated with at least one of said first or second communications nodes.   
     
     
       15. A communications node, comprising:
   a motion predictor configured to obtain a first signal representing a predicted motion of said node;        a data block configured to obtain a second signal representing an actual motion of said node;        an element configured to adjust said first signal based on a difference between said first and second signals; and        a processor configured to compute at least one of a compensated transmission frequency or a compensated receiving frequency based on a predicted relative motion between said node and a second communications node;        wherein said predicted relative motion is based on said first signal and a third signal that is representative of a predicted motion of said second communications node.     
     
     
       16. A communications system, comprising:
   means for predicting a motion of a first communications node to generate a first signal representing the predicted motion of said first communications node;        means for predicting a motion of a second communications node to generate a second signal representing the predicted motion of said second communications node;        a processor to compute at least one of a compensated transmission frequency and a compensated receiving frequency based on said first signal and said second signal;        means for determining an actual motion of said first communications node to generate a third signal representing the actual motion of said first communications node;        means for determining an actual motion of said second communications node to generate a fourth signal representing the actual motion of said second communications node;        means for generating a first feedback signal representing a difference between said first signal and said third signal to improve accuracy of said first signal; and        means for generating a second feedback signal representing a difference between said second signal and said fourth signal to improve accuracy of said second signal.     
     
     
       17. A communications system, comprising:
   a first communications node, including      a first motion predictor to generate a first signal representative of a predicted motion of said first communications node,        a first data block to generate a second signal representative of an actual motion of said first communications node, and        a first element that generates a first feedback signal representative of a difference between said first signal and said second signal to improve accuracy of said first signal;          a second communications node, including      a second motion predictor to generate a third signal representative of a predicted motion of said second communications node,        a second data block to generate a fourth signal representative of an actual motion of said second communications node, and        a second element that generates a second feedback signal representative of a difference between said third signal and said fourth signal to improve accuracy of said third signal; and          a processor to compute at least one of a compensated transmission frequency or a compensated receiving frequency based on said first signal and said third signal.     
     
     
       18. The communications system of  claim 17 , wherein at least one of said first communications node or said second communications node is a moving satellite. 
     
     
       19. The communications system of  claim 17 , wherein at least one of said first communications node or said second communications node is a ground- based station.   
     
     
       20. The communications system of  claim 17 , wherein at least one of said first communications node or said second communications node is a space- based vehicle.   
     
     
       21. The communications system of  claim 17 , wherein at least one of said first communications node or said second communications node is an airborne vehicle. 
     
     
       22. The communications system of  claim 17 , wherein said first communications node or said second communications node includes said processor.