Method and device for mobile station positioning by means of a satellite, and associated transmission method

• US 5,610,615 A
• Filed: 06/20/1995
• Issued: 03/11/1997
• Est. Priority Date: 06/21/1994
• Status: Expired due to Fees

• Current Assignee: Alcatel Mobile Communication France (Nokia Corporation)
• Original Assignee: Alcatel Mobile Communication France (Nokia Corporation)
• Inventors: Chiodini, Alain
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): PHAN, DAO LINDA
• Application Number:
  US08/492,886
• Time in Patent Office: 630 Days
• Field of Search: 342/352, 342/357, 342/354, 455/12.1
• US Class Current: 342/357.78
• CPC Class Codes: G01S 5/0246 involving frequency difference of arrival or Doppler measurements G01S5/02685 takes precedence
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: H04B 7/1855 using a telephonic control signal, e.g. propagation delay variation, Doppler frequency variation, power variation, beam identification

Abstract

A positioning method for a mobile station in the radio coverage area of a satellite entails determining the instantaneous distance between the satellite and the mobile station. The instantaneous elevation angle φ of the satellite is then calculated from the instantaneous distance, the altitude of the satellite and the radius of the Earth. The Doppler shift δ is then determined, after which the angle θ between the projections onto the surface of the Earth of the track of the satellite and a straight line segment passing through the satellite and the mobile station is calculated from the Doppler shift δ and the instantaneous elevation angle φ. The location of the mobile station is then determined from the instantaneous distance, the instantaneous elevation angle φ and the angle θ.

Claims

1. Positioning method for a mobile station in the radio coverage area of a satellite, comprising the following steps:

determining the instantaneous distance between said satellite and said mobile station;

calculating the instantaneous elevation angle φ

of said satellite from said instantaneous distance, the altitude of said satellite and the radius of the Earth;

determining the Doppler shift δ

;

calculating the angle θ

between the projections onto the surface of the Earth of the track of said satellite and a straight line segment passing through said satellite and said mobile station from said Doppler shift δ and

said instantaneous elevation angle φ

; and

determining the location of said mobile station from said instantaneous distance, said instantaneous elevation angle φ and

said angle θ

.

2. Method according to claim 1 wherein said step of calculating said angle θ

comprises the following steps;

calculating the value of cos(θ

) from the Doppler shift equation;

space="preserve" listing-type="equation">δ

=v.sub.s /c.f.sub.p. cos (θ

). cos (φ

)

where;

v_s is the speed of said satellite;

c is the speed of light; and

f_p is the carrier frequency of the transmitted signal; and

resolving uncertainty as to the sign of said angle θ

.

3. Method according to claim 2 further comprising the following steps:

dividing said radio coverage area into two separate regions, a first of which corresponds to a positive value of θ and

a second of which corresponds to a negative value of θ

; and

assigning a separate synchronization signal to each of said regions, and wherein said uncertainty resolving step comprises a step of analyzing the received synchronization signal to determine the region in which said mobile station is located and thereby the sign of θ

.

4. Method according to claim 3 wherein the separation between said regions is defined by the track of said satellite.

5. Method according to claim 1 wherein said step of determining said instantaneous distance comprises a step of measuring the transit time of a signal transmitted between said satellite and said mobile station.

6. Method according to claim 1 wherein said step of determining said Doppler shift δ

uses a pilot signal comprising two juxtaposed temporally symmetrical signal elements of equal duration.

7. Method according to claim 1 wherein said satellite provides a mobile radio service.

8. Method according to claim 1 wherein said satellite conforms to the Globalstar system standards.

9. Mobile station positioning device utilizing the method according to claim 1.