Navigation data structure generation and data transmission for optimal time to first fix

• US 9,405,009 B2
• Filed: 01/20/2012
• Issued: 08/02/2016
• Est. Priority Date: 12/05/2011
• Status: Active Grant

• Current Assignee: Accord Ideation Private Limited
• Original Assignee: Accord Software & Systems Pvt. Ltd.
• Inventors: Maa, Sashidharan, Lachapelle, Ge'rard, Rao, Vyasaraj Guru
• Primary Examiner(s): McGue, Frank J
• Application Number:
  US13/354,329
• Publication Number:
  US 20130141278A1
• Time in Patent Office: 1,656 Days
• Field of Search: 342/357.395, 342/357.39, 342/357.42
• US Class Current: 1/1
• 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 of transmitting a navigation signal comprising navigation data to a satellite navigation receiver, comprising:

providing a signal generation system in each of a plurality of navigation satellites, wherein said signal generation system comprises a data generation unit and a processing unit;

generating characteristic measurements of each of said plurality of navigation satellites, by a measurements module within said data generation unit;

generating a navigation data structure using said generated characteristic measurements, by said data generation unit, wherein said navigation data structure comprises;

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

a third sub-frame configured for accommodating a first set of almanac data, wherein said first set of almanac data comprises Keplerian parameters and ionosphere coefficients; and

a fourth sub-frame configured for accommodating a text message comprising a second set of said almanac data, wherein said second set of said almanac data comprises one or more of coordinated universal time parameters, and periodic non-positioning information extracted from said first sub-frame, said second sub-frame, and said third sub-frame;

processing said generated navigation data structure, by said processing unit, to generate said navigation signal; and

transmitting said generated navigation signal, by said processing unit, to said satellite navigation receiver, via a communication interface.

2. The method of claim 1, wherein each of said plurality of navigation satellites transmits said first data frame, said second data frame, said third data frame, and said fourth data frame using a predetermined pseudo random sequence unique to each of said navigation satellites.

3. 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.

4. 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.

5. A method of processing navigation data by a satellite navigation receiver, comprising:

receiving a navigation signal transmitted from a plurality of navigation satellites, wherein said navigation signal comprises navigation data in a navigation data structure, wherein said navigation data structure comprises;

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

a third sub-frame configured for accommodating a first set of almanac data, wherein said first set of almanac data comprises Keplerian parameters and ionosphere coefficients; and

a fourth sub-frame configured for accommodating a text message comprising a second set of said almanac data, wherein said second set of said almanac data comprises one or more of coordinated universal time parameters, and periodic non-positioning information extracted from said first sub-frame, said second sub-frame, and said third sub-frame;

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 ephemeris data, said first set of said almanac data, and said text message comprising said second set of said almanac data from said validated navigation data based on a sub-frame identifier.

6. The method of claim 5, further comprising:

analyzing timing components that constitute a 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.

7. The method of claim 5, further comprising processing said extracted ephemeris data, said first set of said almanac data, and said text message comprising said second set of said almanac data for determining positions of each of said plurality of navigation satellites for estimating a geographical position of a user.

8. A signal generation system for transmitting a navigation signal comprising navigation data to 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 ephemeris data of said navigation data;

a third sub-frame configured for accommodating a first set of almanac data of said navigation data, wherein said first set of almanac data comprises Keplerian parameters and ionosphere coefficients; and

a fourth sub-frame configured for accommodating a text message comprising a second set of said almanac data, wherein said second set of said almanac data comprises one or more of coordinated universal time parameters, and periodic non-positioning information extracted from said first sub-frame, said second sub-frame, and said third sub-frame; and

a processing unit that processes said generated navigation data structure comprising said ephemeris data, said first set of said almanac data, and said second set of said almanac data to generate said navigation signal, wherein said processing unit transmits said generated navigation signal to said satellite navigation receiver.

9. The signal generation system of claim 8, 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.

10. The signal generation system of claim 8, wherein said characteristic measurements comprise pseudorange measurements and delta-range measurements.

11. The signal generation system of claim 8, 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; 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.

12. A satellite navigation receiver for processing navigation data within a navigation data structure contained in a navigation signal received from a plurality of navigation satellites, comprising:

a navigation data processor, said navigation data processor comprising;

a data extraction module configured for extracting said navigation data from said navigation data structure contained in said navigation signal transmitted by said plurality of navigation satellites, wherein said navigation data structure comprises;

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

a third sub-frame configured for accommodating a first set of almanac data, wherein said first set of almanac data comprises Keplerian parameters and ionosphere coefficients; and

a fourth sub-frame configured for accommodating a text message comprising a second set of said almanac data, wherein said second set of said almanac data comprises one or more of coordinated universal time parameters, and periodic non-positioning information extracted from said first sub-frame, said second sub-frame, and said third sub-frame;

said data extraction module further configured for 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;

said data extraction module further configured for 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;

said data extraction module further configured for performing a cyclic redundancy check operation on said extracted navigation data for validating said extracted navigation data;

said data extraction module further configured for extracting said ephemeris data, said first set of said almanac data, and said text message comprising said second set of said almanac data from said validated navigation data based on a sub-frame identifier; and

a position computation module for processing said extracted ephemeris data, said first set of said almanac data, and said text message comprising said second set of said almanac data for determining positions of each of said plurality of navigation satellites for estimating a geographical position of a user.

13. The satellite navigation receiver of claim 12, further comprising:

a time analysis module for analyzing timing components that constitute a 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.

14. A computer program product comprising a non-transitory computer readable storage medium, said non-transitory computer readable storage medium storing computer program codes that comprise instructions executable by at least one processor, said computer program codes comprising:

a first computer program code configured for execution by at least one processor of a signal generation system, said first computer program code configured for;

generating characteristic measurements of each of said plurality of navigation satellites;

generating a navigation data structure, wherein said navigation data structure comprises;

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

a third sub-frame configured for accommodating a first set of almanac data, wherein said first set of almanac data comprises Keplerian parameters and ionosphere coefficients; and

a fourth sub-frame configured for accommodating a text message comprising a second set of said almanac data, wherein said second set of said almanac data comprises one or more of coordinated universal time parameters, and periodic non-positioning information extracted from said first sub-frame, said second sub-frame, and said third sub-frame;

processing said generated navigation data structure, to generate said navigation signal; and

transmitting said generated navigation signal, to said satellite navigation receiver, via a communication interface;

a second computer program code configured for execution by at least one processor of a satellite navigation receiver, said second computer program code configured for;

receiving a navigation signal transmitted from a plurality of navigation satellites, wherein said navigation signal comprises navigation data in a navigation data structure, wherein said navigation data structure comprises;

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

a third sub-frame configured for accommodating a first set of almanac data, wherein said first set of almanac data comprises Keplerian parameters and ionosphere coefficients; and

a fourth sub-frame configured for accommodating a text message comprising a second set of said almanac data, wherein said second set of said almanac data comprises one or more of coordinated universal time parameters, and periodic non-positioning information extracted from said first sub-frame, said second sub-frame, and said third sub-frame;

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 ephemeris data, said first set of said almanac data, and said text message comprising said second set of said almanac data from said validated navigation data based on a sub-frame identifier.