Navigation Data Configuration For Optimal Time To First Fix

• US 20140327575A1
• Filed: 09/05/2013
• Published: 11/06/2014
• Est. Priority Date: 05/06/2013
• Status: Active Grant

• Current Assignee: Accord Ideation Private Limited
• Original Assignee: Accord Software & Systems Pvt. Ltd.
• Inventors: Rao, Vyasaraj Guru
• Granted Patent: US 9,638,803 B2
• Time in Patent Office: Days
• US Class Current: 342/357.63
• CPC Class Codes: G01S 19/05 providing aiding data

Abstract

A method and a system for reducing time to first fix (TTFF) in a satellite navigation receiver generate a navigation data structure including three sub-frames. A first sub-frame and a second sub-frame accommodate selective ephemeris data. The third sub-frame accommodates a text message including almanac data optionally, ionospheric data, coordinated universal time (UTC) data, textual data optionally, and any combination thereof. A signal generation system (SGS) in the system selectively groups the almanac data, the ionospheric data, and the UTC data, and selectively transmits the navigation data with the almanac data or free of the almanac data in the navigation data structure to the satellite navigation receiver. The signal generation system also staggers the navigation data in each sub-frame into a first portion and a second portion for parallelly transmitting the navigation data over a first carrier frequency and a second carrier frequency in reduced time.

Claims

1. A method for reducing time to first fix in a satellite navigation receiver, comprising:

generating a navigation data structure configured to accommodate navigation data, said navigation data structure comprising;

a first sub-frame and a second sub-frame configured to accommodate selective ephemeris data of said navigation data, wherein said first sub-frame and said second sub-frame are configured to reduce time for collecting said ephemeris data by said satellite navigation receiver; and

a third sub-frame configured to accommodate a text message comprising almanac data, ionospheric data, coordinated universal time data, textual data, and any combination thereof, wherein said third sub-frame is configured to reduce time for collecting said almanac data, said ionospheric data, said coordinated universal time data, and said textual data by said satellite navigation receiver;

selectively grouping said almanac data, said ionospheric data, and said coordinated universal time data; and

selectively transmitting said ephemeris data, said selectively grouped almanac data, ionospheric data, and coordinated universal time data, and said textual data in said generated navigation data structure to said satellite navigation receiver, wherein said transmission comprises alternatively transmitting said ionospheric data and said coordinated universal time data with said almanac data and free of said almanac data in said third sub-frame in said generated navigation data structure to transmit said navigation data in reduced time, thereby reducing said time to first fix in said satellite navigation receiver.

2. The method of claim 1, wherein each of a plurality of satellites of a constellation is configured to simultaneously and selectively transmit said selective ephemeris data, said selectively grouped almanac data, ionospheric data, and coordinated universal time data, and said textual data in said generated navigation data structure to said satellite navigation receiver, thereby allowing said satellite navigation receiver to receive collective said selective ephemeris data, said almanac data, said ionospheric data, said coordinated universal time data, and said textual data in said reduced time, thereby further reducing said time to first fix in said satellite navigation receiver.

3. The method of claim 1, further comprising verifying integrity of said navigation data in said first sub-frame, said second sub-frame, and said third sub-frame of said generated navigation data structure for determining accuracy of said navigation data.

4. The method of claim 1, wherein said text message in said third sub-frame of said generated navigation data structure is further configured to accommodate periodic non-positioning information extracted from said first sub-frame and said second sub-frame, wherein said periodic non-positioning information comprises telemetry data.

5. The method of claim 1, wherein each of said first sub-frame, said second sub-frame, and said third sub-frame of said generated navigation data structure comprises 288 bits of said navigation data and 6 bits of tail data.

6. The method of claim 1, wherein said generation of said navigation data structure comprises appending a synchronization word to each of said first sub-frame, said second sub-frame, and said third sub-frame, wherein said synchronization word is configured to enable frame synchronization and identification of a sub-frame boundary of said each of said first sub-frame, said second sub-frame, and said third sub-frame.

7. The method of claim 1, further comprising receiving navigation signals comprising said navigation data in said generated navigation data structure from a plurality of satellites of a constellation by said satellite navigation receiver, wherein said satellite navigation receiver is configured to extract said navigation data from said received navigation signals by:

determining a sub-frame boundary of each of said first sub-frame, said second sub-frame, and said third sub-frame in said generated navigation data structure by searching for a synchronization word in said generated navigation data structure;

decoding said each of said first sub-frame, said second sub-frame, and said third sub-frame in said generated navigation data structure for extracting said navigation data;

performing a cyclic redundancy check operation on said extracted navigation data for validating said extracted navigation data; and

extracting said selective ephemeris data, said almanac data, said ionospheric data, said coordinated universal time data, and said textual data from said validated navigation data based on a sub-frame identifier.

8. A method for reducing time to first fix in a satellite navigation receiver in a single frequency of operation, comprising:

generating a navigation data structure configured to accommodate navigation data, said navigation data structure comprising;

a first sub-frame and a second sub-frame configured to accommodate selective ephemeris data of said navigation data, wherein said first sub-frame and said second sub-frame are configured to reduce time for collecting said ephemeris data by said satellite navigation receiver; and

a third sub-frame configured to accommodate a text message comprising ionospheric data and coordinated universal time data, wherein said third sub-frame is configured to reduce time for collecting said ionospheric data and said coordinated universal time data by said satellite navigation receiver; and

transmitting said ephemeris data, said ionospheric data, and said coordinated universal time data free of almanac data in said generated navigation data structure to said satellite navigation receiver, thereby reducing said time to first fix in said satellite navigation receiver, wherein said ionospheric data and said coordinated universal time data are transmitted by one of a plurality of satellites of a constellation to said satellite navigation receiver.

9. The method of claim 8, further comprising determining a mode of operation for transmitting said navigation data in said generation navigation data structure, wherein said mode of operation is one of a civilian mode and a restricted mode.

10. The method of claim 8, further comprising altering transmission of said navigation data after said transmission of said ionospheric data and said coordinated universal time data to further reduce said time to first fix in said satellite navigation receiver.

11. A method for reducing time to first fix in a satellite navigation receiver, comprising:

generating a navigation data structure comprising sub-frames configured to selectively accommodate navigation data, said navigation data comprising selective ephemeris data, ionospheric data, coordinated universal time data, textual data, and any combination thereof, wherein said sub-frames are configured to reduce time for collecting said navigation data by said satellite navigation receiver;

staggering said navigation data in each of said sub-frames of said generated navigation data structure into a first portion and a second portion; and

parallelly transmitting said each of said sub-frames of said generated navigation data structure over a first carrier frequency and a second carrier frequency by each of a plurality of satellites of a constellation to obtain said navigation data in reduced time, thereby reducing said time to first fix in said satellite navigation receiver.

12. The method of claim 11, wherein said parallel transmission of said each of said sub-frames of said generated navigation data structure comprises:

sequentially transmitting said first portion and said second portion of said each of said sub-frames over said first carrier frequency and said second carrier frequency in a first mode of service; and

sequentially transmitting a complementary of said first portion and said second portion of said each of said sub-frames over said second carrier frequency and said first carrier frequency in a second mode of service.

13. The method of claim 11, wherein said parallel transmission of said each of said sub-frames of said generated navigation data structure comprises:

sequentially transmitting said first portion and said second portion of said each of said sub-frames over said first carrier frequency, and a complementary of said first portion and said second portion of said each of said sub-frames over said second carrier frequency in a first mode of service to obtain time of week data;

sequentially transmitting said second portion of one of said sub-frames and said first portion of another one of said sub-frames, and a complementary of said second portion of said one of said sub-frames and said first portion of said another one of said sub-frames over said first carrier frequency in a second mode of service; and

sequentially transmitting said first portion of said one of said sub-frames and said second portion of said another one of said sub-frames, and a complementary of said first portion of said one of said sub-frames and said second portion of said another one of said sub-frames over said second carrier frequency in said second mode of service, wherein said second mode of service is assisted by said first mode of service for availing said obtained time of week data in reduced time, thereby reducing said time to first fix in said satellite navigation receiver.

14. A method for reducing time to first fix in a satellite navigation receiver in a civilian mode of operation, comprising:

generating a navigation data structure comprising sub-frames configured to selectively accommodate navigation data, said navigation data comprising selective ephemeris data, ionospheric data, coordinated universal time data, textual data, and any combination thereof, wherein said sub-frames are configured to reduce time for collecting said navigation data by said satellite navigation receiver;

staggering said navigation data in each of said sub-frames of said generated navigation data structure into a first portion and a second portion; and

parallelly transmitting said each of said sub-frames of said generated navigation data structure comprising distinct said staggered navigation data over a first carrier frequency and a second carrier frequency by each of a plurality of satellites of a constellation to obtain said navigation data in reduced time, thereby reducing said time to first fix in said satellite navigation receiver in said civilian mode of operation, wherein said first portion and said second portion of said each of said sub-frames are transmitted sequentially over said first carrier frequency and said second carrier frequency in a first mode of service, and wherein a complementary of said first portion and said second portion of said each of said sub-frames are transmitted sequentially over said second carrier frequency and said first carrier frequency in a second mode of service.

15. The method of claim 14, wherein said textual data is sequentially swept cyclically across said satellites on each of said first carrier frequency and said second carrier frequency in one of said first mode of service and said second mode of service.

16. The method of claim 14, wherein each of said satellites is configured to transmit distinct said staggered navigation data on each of said first carrier frequency and said second carrier frequency.

17. The method of claim 14, wherein said textual data, said ionospheric data, and said coordinated universal time data of said navigation data are alternatively transmitted in said sub-frames on one of said first carrier frequency and said second carrier frequency.

18. A method for reducing time to first fix in a satellite navigation receiver in a restricted mode of operation, comprising:

generating a navigation data structure comprising sub-frames configured to selectively accommodate navigation data, said navigation data comprising selective ephemeris data, ionospheric data, coordinated universal time data, textual data, and any combination thereof, wherein said sub-frames are configured to reduce time for collecting said navigation data by said satellite navigation receiver;

staggering said navigation data in each of said sub-frames of said generated navigation data structure into a first portion and a second portion; and

parallelly transmitting said each of said sub-frames over a first carrier frequency and a second carrier frequency by each of a plurality of satellites of a constellation to obtain said navigation data in reduced time, thereby reducing said time to first fix in said satellite navigation receiver in said restricted mode of operation, wherein said parallel transmission of said each of said sub-frames comprises;

sequentially transmitting said first portion and said second portion of said each of said sub-frames over said first carrier frequency, and a complementary of said first portion and said second portion of said each of said sub-frames over said second carrier frequency in a first mode of service to obtain time of week data;

sequentially transmitting said second portion of one of said sub-frames and said first portion of another one of said sub-frames, and a complementary of said second portion of said one of said sub-frames and said first portion of said another one of said sub-frames over said first carrier frequency in a second mode of service; and

sequentially transmitting said first portion of said one of said sub-frames and said second portion of said another one of said sub-frames, and a complementary of said first portion of said one of said sub-frames and said second portion of said another one of said sub-frames over said second carrier frequency in said second mode of service, wherein said second mode of service is assisted by said first mode of service for availing said obtained time of week data in reduced time.

19. A system for selectively transmitting navigation data configured to reduce time to first fix in a satellite navigation receiver, comprising:

a navigation data generation module configured to generate a navigation data structure, wherein said navigation data generation module comprises;

a sub-frame generation module configured to generate sub-frames of said navigation data structure, said sub-frames configured to selectively accommodate said navigation data, said sub-frames comprising;

a first sub-frame and a second sub-frame configured to accommodate selective ephemeris data of said navigation data, wherein said first sub-frame and said second sub-frame are configured to reduce time for collecting said ephemeris data by said satellite navigation receiver; and

a third sub-frame configured to accommodate a text message comprising almanac data, ionospheric data, coordinated universal time data, textual data, and any combination thereof, wherein said third sub-frame is configured to reduce time for collecting said almanac data, said ionospheric data, said coordinated universal time data, and said textual data by said satellite navigation receiver; and

a data configuration module configured to configure said navigation data in each of said sub-frames of said generated navigation data structure; and

a transmission module configured to selectively transmit said configured navigation data in said generated navigation structure to said satellite navigation receiver in reduced time, thereby reducing said time to first fix in said satellite navigation receiver.

20. The system of claim 19, wherein said data configuration module is configured to selectively group said almanac data, said ionospheric data, and said coordinated universal time data.

21. The system of claim 20, wherein said transmission module is further configured to selectively transmit said ephemeris data, said selectively grouped almanac data, ionospheric data, and coordinated universal time data, and said textual data in said generated navigation data structure to said satellite navigation receiver.

22. The system of claim 19, wherein said transmission module is further configured to alternatively transmit said ionospheric data and said coordinated universal time data with said almanac data and free of said almanac data in said third sub-frame in said generated navigation data structure to transmit said navigation data in reduced time.

23. The system of claim 19, wherein said transmission module is further configured to simultaneously and selectively transmit said selective ephemeris data, said selectively grouped almanac data, ionospheric data, and coordinated universal time data, and said textual data in said generated navigation data structure to said satellite navigation receiver, thereby allowing said satellite navigation receiver to receive collective said selective ephemeris data, said almanac data, said ionospheric data, said coordinated universal time data, and said textual data in said reduced time, thereby further reducing said time to first fix in said satellite navigation receiver.

24. The system of claim 19, wherein said sub-frame generation module is configured to append a synchronization word to each of said first sub-frame, said second sub-frame, and said third sub-frame, wherein said synchronization word is configured to enable frame synchronization and identification of a sub-frame boundary of said each of said first sub-frame, said second sub-frame, and said third sub-frame.

25. The system of claim 19, wherein said transmission module is further configured to transmit said ephemeris data, said ionospheric data, and said coordinated universal time data free of said almanac data in said generated navigation data structure to said satellite navigation receiver, wherein said ionospheric data and said coordinated universal time data are transmitted by one of a plurality of satellites of a constellation to said satellite navigation receiver.

26. The system of claim 19, wherein said transmission module is further configured to alter said transmission of said navigation data after said transmission of said ionospheric data and said coordinated universal time data to further reduce said time to first fix in said satellite navigation receiver.

27. The system of claim 19, wherein said data configuration module configured to stagger said navigation data in said each of said sub-frames of said generated navigation data structure into a first portion and a second portion.

28. The system of claim 27, wherein said transmission module is further configured to parallelly transmit said each of said sub-frames comprising distinct said staggered navigation data over a first carrier frequency and a second carrier frequency to obtain said navigation data in reduced time, wherein said first portion and said second portion of said each of said sub-frames are transmitted sequentially over said first carrier frequency and said second carrier frequency in a first mode of service, and wherein a complementary of said first portion and said second portion of said each of said sub-frames are transmitted sequentially over said second carrier frequency and said first carrier frequency in a second mode of service.

29. The system of claim 28, wherein said data configuration module is further configured to sequentially sweep said textual data cyclically across satellites on each of said first carrier frequency and said second carrier frequency in one of said first mode of service and said second mode of service.

30. The system of claim 28, wherein said transmission module is further configured to transmit distinct said staggered navigation data in on each of said first carrier frequency and said second carrier frequency.

31. The system of claim 27, wherein said transmission module is further configured to parallelly transmit said each of said sub-frames over a first carrier frequency and a second carrier frequency to obtain said navigation data in reduced time, wherein said parallel transmission of said each of said sub-frames comprises:

sequentially transmitting said first portion and said second portion of said each of said sub-frames over said first carrier frequency, and a complementary of said first portion and said second portion of said each of said sub-frames over said second carrier frequency in a first mode of service to obtain time of week data;

sequentially transmitting said second portion of one of said sub-frames and said first portion of another one of said sub-frames, and a complementary of said second portion of said one of said sub-frames and said first portion of said another one of said sub-frames over said first carrier frequency in a second mode of service; and

sequentially transmitting said first portion of said one of said sub-frames and said second portion of said another one of said sub-frames, and a complementary of said first portion of said one of said sub-frames and said second portion of said another one of said sub-frames over said second carrier frequency in said second mode of service, wherein said second mode of service is assisted by said first mode of service for availing said obtained time of week data in reduced time, thereby reducing said time to first fix in said satellite navigation receiver.

32. The system of claim 19, wherein said transmission module is further configured to alternatively transmit said textual data, said ionospheric data, and said coordinated universal time data of said navigation data in said sub-frames on one of a first carrier frequency and a second carrier frequency.