Navigation Data Structure Generation And Data Transmission For Optimal Time To First Fix

• US 20130141278A1
• Filed: 01/20/2012
• Published: 06/06/2013
• Est. Priority Date: 12/05/2011
• Status: Active Grant

• Current Assignee: Accord Ideation Private Limited
• Original Assignee: Accord Software & Systems Pvt. Ltd.
• Inventors: Rao, Vyasaraj Guru
• Granted Patent: US 9,405,009 B2
• Time in Patent Office: Days
• US Class Current: 342/357.44
• CPC Class Codes: G01S 19/01 Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
• CPC Class Codes: G01S 19/02 Details of the space or ground control segments
• CPC Class Codes: G01S 19/235 Calibration of receiver components

Abstract

A method and system for transmitting navigation data to a satellite navigation receiver for reducing time to first fix is provided. A signal generation system generates a navigation data structure comprising a first sub-frame and a second sub-frame for accommodating selective ephemeris data, a third sub-frame for accommodating first parameters of almanac data, and a fourth sub-frame for accommodating a text message comprising second parameters of almanac data, and transmits the selective ephemeris data and the first and second parameters of almanac data to the satellite navigation receiver. The configuration of the navigation data structure enables the satellite navigation receiver to collect the navigation data in reduced time. Each satellite of a constellation simultaneously transmits distinct first parameters of the almanac data in the third sub-frame of the navigation data structure to the satellite navigation receiver, thereby allowing the satellite navigation receiver to receive collective almanac data in reduced time.

Claims

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

generating a navigation data structure comprising;

a first sub-frame and a second sub-frame configured for accommodating selective ephemeris data of said navigation data, wherein said configuration of said first sub-frame and said second sub-frame reduces time for collecting said selective ephemeris data by said satellite navigation receiver;

a third sub-frame configured for accommodating first parameters of almanac data of said navigation data, wherein said configuration of said third sub-frame reduces time for collecting said first parameters of said almanac data by said satellite navigation receiver; and

a fourth sub-frame configured for accommodating a text message comprising second parameters of said almanac data, wherein said configuration of said fourth sub-frame reduces time for collecting said second parameters of said almanac data by said satellite navigation receiver; and

transmitting said selective ephemeris data, said first parameters of said almanac data, and said second parameters of said almanac data in said generated navigation data structure to said satellite navigation receiver 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 simultaneously transmits distinct said first parameters of said almanac data in said third sub-frame of said generated navigation data structure to said satellite navigation receiver, thereby allowing said satellite navigation receiver to receive collective said almanac data in 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, said third sub-frame, and said fourth sub-frame for determining accuracy of said navigation data.

4. The method of claim 1, wherein said first parameters of said almanac data accommodated in said third sub-frame of said generated navigation data structure comprise selective Keplerian parameters and ionosphere coefficients.

5. The method of claim 1, wherein said second parameters of said almanac data accommodated in said fourth sub-frame of said generated navigation data structure comprise coordinated universal time parameters.

6. The method of claim 1, wherein said text message in said fourth sub-frame further comprises periodic non-positioning information extracted from said first sub-frame, said second sub-frame, and said third sub-frame, wherein said periodic non-positioning information comprises telemetry data.

7. The method of claim 1, wherein each of said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame comprises 245 bits of said navigation data and 24 bits of a cyclic redundancy check code for enabling validation of said navigation data.

8. 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, said third sub-frame, and said fourth sub-frame for enabling frame synchronization and identification of a sub-frame boundary of said each of said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame.

9. 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 extracts 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, said third sub-frame, and said fourth 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, said third sub-frame, and said fourth 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 first parameters of said almanac data, and said text message comprising said second parameters of said almanac data from said validated navigation data based on a sub-frame identifier.

10. The method of claim 1, further comprising analyzing timing components that constitute said time to first fix by said satellite navigation receiver, and identifying timing delays at said satellite navigation receiver, wherein said timing components comprise:

a time for boot-up of said satellite navigation receiver;

a time for acquiring coarse estimates of a code phase and a carrier Doppler frequency of visible satellites of a constellation over satellite channels corresponding to said visible satellites;

a time for performing bit synchronization of said satellite channels corresponding to said visible satellites;

a time for extracting said navigation data from said generated navigation data structure contained in navigation signals received from said visible satellites by said satellite navigation receiver; and

a time for computing a geographical position of a user based on said extracted navigation data.

11. The method of claim 1, further comprising processing said selective ephemeris data and said first parameters of said almanac data extracted from said generated navigation data structure by said satellite navigation receiver for determining positions of individual satellites of a constellation and using said determined positions of said individual satellites for estimating a geographical position of a user.

12. A method for transmitting almanac data to a satellite navigation receiver for reducing time required for collecting said almanac data by said satellite navigation receiver, comprising:

generating a navigation data structure comprising;

a first sub-frame and a second sub-frame configured for accommodating selective ephemeris data of navigation data;

a third sub-frame configured for accommodating first parameters of said almanac data of said navigation data; and

a fourth sub-frame configured for accommodating a text message comprising second parameters of said almanac data; and

transmitting said selective ephemeris data, said first parameters of said almanac data, and said second parameters of said almanac data in said generated navigation data structure to said satellite navigation receiver, wherein each of a plurality of satellites of a constellation simultaneously transmits distinct said first parameters of said almanac data in said third sub-frame of said generated navigation data structure to said satellite navigation receiver, thereby allowing said satellite navigation receiver to receive collective said almanac data in reduced time.

13. The method of claim 12, wherein said transmission of said distinct said first parameters of said almanac data by said each of said satellites to said satellite navigation receiver comprises:

selecting a distinct almanac page of said almanac data for transmission by said each of said satellites at each time instant, wherein said selected distinct almanac page of said almanac data of said each of said satellites constitutes said collective said almanac data for said constellation of said satellites; and

transmitting said selected distinct almanac page of said each of said satellites to said satellite navigation receiver via a separate satellite channel associated with said each of said satellites.

14. A signal generation system for generating a navigation signal that enables reduction of time to first fix in a satellite navigation receiver, comprising:

a data generation unit comprising;

a measurements module that generates characteristic measurements of each satellite of a constellation; and

a navigation data generation module that generates a navigation data structure using said generated characteristic measurements, wherein said generated navigation data structure comprises;

a first sub-frame and a second sub-frame configured for accommodating selective ephemeris data of said navigation data, wherein said configuration of said first sub-frame and said second sub-frame reduces time for collecting said selective ephemeris data by said satellite navigation receiver;

a third sub-frame configured for accommodating first parameters of almanac data of said navigation data, wherein said configuration of said third sub-frame reduces time for collecting said first parameters of said almanac data by said satellite navigation receiver; and

a fourth sub-frame configured for accommodating a text message comprising second parameters of said almanac data, wherein said configuration of said fourth sub-frame reduces time for collecting said second parameters of said almanac data by said satellite navigation receiver; and

a processing unit that processes said generated navigation data structure comprising said selective ephemeris data, said first parameters of said almanac data, and said second parameters of said almanac data to generate said navigation signal, wherein said processing unit transmits said generated navigation signal to said satellite navigation receiver in reduced time, thereby reducing said time to first fix in said satellite navigation receiver.

15. The signal generation system of claim 14, wherein said processing unit comprises:

a modulation module that generates a carrier frequency and a ranging code for a satellite channel associated with said each satellite over which said generated navigation signal is to be transmitted;

said modulation module that modulates said navigation data in said generated navigation data structure with said generated carrier frequency and said generated ranging code to generate an intermediate frequency signal; and

an up-converter that translates said intermediate frequency signal to generate said navigation signal.

16. The signal generation system of claim 14, wherein said processing unit simultaneously transmits distinct said first parameters of said almanac data in said third sub-frame of said generated navigation data structure of said each satellite to said satellite navigation receiver, thereby allowing said satellite navigation receiver to receive collective said almanac data in said reduced time, thereby further reducing said time to first fix in said satellite navigation receiver.

17. The signal generation system of claim 14, wherein said characteristic measurements comprise pseudorange measurements and delta-range measurements.

18. The signal generation system of claim 14, wherein said navigation data generation module of said data generation unit comprises:

a sub-frame generation module that generates said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame using said selective ephemeris data, said almanac data, and said text message extrapolated from preconfigured navigation data files associated with said each satellite;

a cyclic redundancy check module that computes cyclic redundancy check bits for each of said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame, for enabling validation of said navigation data by said satellite navigation receiver; and

an encoder that applies a forward error correcting code to said navigation data for encoding each said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame, and generating symbols of said navigation data.

19. A satellite navigation receiver comprising a navigation data processor, said navigation data processor comprising:

a data extraction module that extracts navigation data from a navigation data structure contained in navigation signals transmitted by a plurality of satellites of a constellation in reduced time, wherein said navigation data structure comprises;

a first sub-frame and a second sub-frame configured for accommodating selective ephemeris data of said navigation data, wherein said configuration of said first sub-frame and said second sub-frame reduces time for collecting said selective ephemeris data by said satellite navigation receiver;

a third sub-frame configured for accommodating first parameters of almanac data of said navigation data, wherein said configuration of said third sub-frame reduces time for collecting said first parameters of said almanac data by said satellite navigation receiver; and

a fourth sub-frame configured for accommodating a text message comprising second parameters of said almanac data, wherein said configuration of said fourth sub-frame reduces time for collecting said second parameters of said almanac data by said satellite navigation receiver; and

a position computation module that processes said extracted navigation data for computing a position of each of said satellites and estimating a geographical position of a user based on said processed navigation data in reduced time.

20. The satellite navigation receiver of claim 19, further comprising a communication interface that simultaneously receives distinct said first parameters of said almanac data in said third sub-frame of said navigation data structure from said each of said satellites, thereby allowing said satellite navigation receiver to receive collective said almanac data in said reduced time, thereby reducing time to first fix in said satellite navigation receiver.

21. A system for transmitting navigation data to a satellite navigation receiver for reducing time to first fix in said satellite navigation receiver, comprising:

a signal generation system comprising;

a navigation data generation module that generates a navigation data structure, wherein said generated navigation data structure comprises;

a first sub-frame and a second sub-frame configured for accommodating selective ephemeris data of said navigation data;

a third sub-frame configured for accommodating first parameters of almanac data of said navigation data; and

a fourth sub-frame configured for accommodating a text message comprising second parameters of said almanac data; and

a processing unit that processes said generated navigation data structure comprising said selective ephemeris data, said first parameters of said almanac data, and said second parameters of said almanac data to generate a navigation signal, wherein said processing unit transmits said generated navigation signal to said satellite navigation receiver via a communication interface in reduced time; and

said satellite navigation receiver that receives said generated navigation signal in said reduced time, extracts said navigation data from said received navigation signal, and processes said extracted navigation data in said reduced time, thereby reducing said time to first fix in said satellite navigation receiver.

22. The system of claim 21, wherein said signal generation system further comprises a measurements module that generates characteristic measurements of each satellite of said constellation, wherein said characteristic measurements comprise pseudorange measurements and delta-range measurements.

23. The system of claim 21, wherein said processing unit of said signal generation system comprises:

a modulation module that generates a carrier frequency and a ranging code for a satellite channel associated with said each satellite over which said generated navigation signal is to be transmitted;

said modulation module that modulates said navigation data in said generated navigation data structure with said generated carrier frequency and said generated ranging code to generate an intermediate frequency signal; and

an up-converter that translates said intermediate frequency signal to generate said navigation signal.

24. The system of claim 21, wherein said navigation data generation module of said signal generation system comprises:

a sub-frame generation module that generates said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame using said selective ephemeris data, said almanac data, and said text message extrapolated from preconfigured navigation data files associated with said each satellite;

a cyclic redundancy check module that computes cyclic redundancy check bits for each of said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame for enabling validation of said navigation data by said satellite navigation receiver; and

an encoder that applies a forward error correcting code to said navigation data for encoding each said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame, and generating symbols of said navigation data.

25. The system of claim 21, wherein said satellite navigation receiver comprises:

a down-converter that converts said received navigation signal to an intermediate frequency signal;

an analog to digital converter that converts said intermediate frequency signal to digital samples;

a correlator that correlates said digital samples with locally generated signals; and

a navigation data processor that decodes said correlated digital samples for extracting said navigation data from said generated navigation data structure, and processes said extracted navigation data for computing position of each satellite and determining a geographical position of a user based on said processed navigation data.

26. The system of claim 25, wherein said navigation data processor comprises a time analysis module that analyzes timing components that constitute said time to first fix, and identifies timing delays at said satellite navigation receiver, wherein said timing components comprise:

a time for boot-up of said satellite navigation receiver;

a time for acquiring coarse estimates of a code phase and a carrier Doppler frequency of visible satellites of a constellation over satellite channels corresponding to said visible satellites;

a time for performing bit synchronization of said satellite channels corresponding to said visible satellites;

a time for extracting said navigation data from said generated navigation data structure contained in navigation signals received from said visible satellites by said satellite navigation receiver; and

a time for computing a geographical position of a user based on said extracted navigation data.

27. The system of claim 21, wherein said processing unit of said signal generation system comprises an almanac data control module that simultaneously transmits distinct said first parameters of said almanac data in said third sub-frame of said generated navigation data structure to said satellite navigation receiver via said communication interface, thereby allowing said satellite navigation receiver to receive collective said almanac data in reduced time, thereby further reducing said time to first fix in said satellite navigation receiver.

28. The system of claim 27, wherein said almanac data control module performs:

selecting a distinct almanac page of said almanac data for transmission to said satellite navigation receiver, wherein said selected distinct almanac page of said almanac data of said each of said satellites constitutes said collective said almanac data for said constellation of said satellites; and

transmitting said selected distinct almanac page to said satellite navigation receiver via said communication interface for said each of said satellites.

29. A navigation data structure, comprising:

a first sub-frame and a second sub-frame configured for accommodating selective ephemeris data of navigation data, wherein said configuration of said first sub-frame and said second sub-frame reduces time for collecting said selective ephemeris data by a satellite navigation receiver;

a third sub-frame configured for accommodating first parameters of almanac data of said navigation data, wherein said configuration of said third sub-frame reduces time for collecting said first parameters of said almanac data by said satellite navigation receiver; and

a fourth sub-frame configured for accommodating a text message comprising second parameters of said almanac data, wherein said configuration of said fourth sub-frame reduces time for collecting said second parameters of said almanac data by said satellite navigation receiver;

whereby said configuration of said first sub-frame, said second sub-frame, said third sub-frame, and said fourth sub-frame enables reduction of time to first fix in said satellite navigation receiver.