Satellite-based positioning system improvement

• US 8,816,905 B2
• Filed: 02/24/2012
• Issued: 08/26/2014
• Est. Priority Date: 10/04/2002
• Status: Expired due to Term

• Current Assignee: U-Blox AG (u-blox Holding AG)
• Original Assignee: U-Blox AG (u-blox Holding AG)
• Inventors: Bryant, Roderick C., Dempster, Andrew G., Dougan, Stanley L., Hobbs, Trevor, Glennon, Eamonn P.
• Primary Examiner(s): Issing, Gregory C
• Application Number:
  US13/404,304
• Publication Number:
  US 20120249367A1
• Time in Patent Office: 914 Days
• Field of Search: 342/357.66
• US Class Current: 342/357.66
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04B 2201/70715 with application-specific features

Abstract

A method, device and system for determining a receiver location using weak signal satellite transmissions. The invention involves a sequence of exchanges between an aiding source and a receiver that serve to provide aiding information to the receiver so that the receiver'"'"'s location may be determined in the presence of weak satellite transmissions. With the aiding information, the novel receiver detects, acquires and tracks weak satellite signals and computes position solutions from calculated pseudo ranges despite the inability to extract time synchronization date from the weak satellite signals. The invention includes as features, methods and apparatus for the calibration of a local oscillator, the cancellation of cross correlations, a Doppler location scheme, an ensemble averaging scheme, the calculation of almanac aiding from a table of orbit coefficients, absolute time determination, and a modified search engine.

Claims

1. A satellite-based positioning system for identifying a location of a receiver in the presence of satellite signal attenuation comprising:

a plurality of orbital satellites sending synchronized encoded signals that have repeated epochs containing synchronization data; and

a receiver configured to;

detect, acquire, and track a set of the encoded signals transmitted by a set of the orbital satellites,

simultaneously determine code phases of said set of encoded signals with respect to said epochs,

receive aiding information broadcast from an aiding source,

compute positions of the set of satellites using orbital coefficients hardcoded in the receiver for a number of satellite orbits and the received aiding information, and

compute the position of the receiver based on said computed positions of the set of satellites and on pseudoranges derived from the code phases.

2. A receiver for identifying its location using a satellite-based positioning system including a plurality of orbital satellites sending synchronized encoded signals that have repeated epochs containing synchronization data, in the presence of satellite signal attenuation,

the receiver configured to:

detect, acquire, and track a set of the encoded signals transmitted by a set of the orbital satellites,

simultaneously determine code phases of said set of encoded signals with respect to said epochs,

receive aiding information broadcast from an aiding source,

compute positions of the set of satellites using orbital coefficients hardcoded in the receiver for a number of satellite orbits and the received aiding information, and

compute the position of the receiver based on said computed positions of the set of satellites and on pseudoranges derived from the code phases.

3. The receiver of claim 2 further comprising a look-up table wherein said hardcoded orbital coefficients are stored.

4. The receiver of claim 2, wherein the received aiding information is related to at least some of the satellites that are visible to the receiver.

5. The receiver of claim 4, wherein the received aiding information includes a satellite identification, an identifier of the stored hardcoded orbital coefficients, and corrections to the orbital coefficients or additional orbital coefficients or corrections to the output after using the hardcoded orbital coefficients.

6. The receiver of claim 2, wherein the received aiding information includes a reference time of week.

7. A method for identifying a location of a receiver using a satellite-based positioning system with a plurality of orbital satellites sending synchronized encoded signals which have repeated epochs containing synchronization data, in the presence of satellite signal attenuation, the method, implemented in the receiver, comprising:

detecting, acquiring and tracking a set of encoded signals transmitted by a set of satellites of the satellite-based positioning system,

simultaneously determining the code phases of said set of encoded signals,

receiving aiding information broadcast from an aiding source,

computing positions of the set of satellites using orbital coefficients hardcoded in the receiver for a number of satellite orbits and the received aiding information,

computing the position of the receiver based on said computed positions of the set of satellites and on pseudoranges derived from said code phases.

8. The method of claim 7, wherein the said hardcoded orbital coefficients are read from a look-up table.

9. The method of claim 7, wherein the received aiding information is related to at least some of the satellites that are visible to the receiver.

10. The method of claim 9, wherein the received aiding information includes a satellite identification, an identifier of the stored hardcoded orbital coefficients, and corrections to the orbital coefficients or additional orbital coefficients or corrections to the output after using the hardcoded orbital coefficients.

11. The method of claim 9, wherein the received aiding information includes a reference time of week.