Satellite-based geolocation calibration system and method

• US 5,617,101 A
• Filed: 12/27/1994
• Issued: 04/01/1997
• Est. Priority Date: 12/27/1994
• Status: Expired due to Term

• Current Assignee: CDC Propriete Intellectuelle
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Heuvel, Dean P. V., McKay, Brent M., Maine, Kristine P.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/363,854
• Time in Patent Office: 826 Days
• Field of Search: 342/357, 342/358, 342/174, 455/9, 455/10, 455/54.1, 455/54.2, 455/67.5, 455/67.1, 455/12.1, 455/13.1
• US Class Current: 342/358
• CPC Class Codes: H04B 17/11 for calibration
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 17/27 for locating or positioning the transmitter
• CPC Class Codes: H04B 7/1855 using a telephonic control signal, e.g. propagation delay variation, Doppler frequency variation, power variation, beam identification
• CPC Class Codes: H04B 7/2125 Synchronisation

Abstract

A calibration system utilizing existing location techniques for a global radio telecommunication system 10 autonomously calibrates the communication system'"'"'s location system by routing precision location data through system 10. Calibration reduces system errors by allowing time slots to remain narrow. The precision data is carried by existing commands throughout the system to measure location errors inserted by satellites 12. A gateway 16 compiles and evaluates received calibration data and determines when to update all gateways 16 with new satellite variance data tables 435. The calibration system provides early warning of degradation of system components and long-term analysis of system performance.

Claims

1. In a radio telecommunication system employing accurate location data of a user for communication routing and access control, a method of calibrating said radio telecommunication system to generate said accurate location data from measured signal parameters as measured by said user and modified by variance data stored in a gateway, said method comprising the steps of:

(a) generating measured signal parameters between a satellite and a calibration subscriber unit;

(b) receiving precision location data from an alternate location source at said calibration subscriber unit;

(c) forwarding said measured signal parameters and said precision location data to said gateway from said satellite; and

(d) generating said variance data to be used to correct subsequent location processing at said gateway.

2. A method as recited in claim 1, wherein step (b) comprises the steps of:

(b1) performing a current location process using said alternate location source; and

(b2) said alternate location source forwarding said precision location data to said calibration subscriber unit.

3. A method as recited in claim 1, wherein step (b) comprises the steps of:

(b11) receiving precision location data associated with a fixed-location data source; and

(b12) forwarding said precision location data to said calibration subscriber unit associated with a fixed site.

4. A method as recited in claim 3, wherein step (b11) further comprises the step of entering said fixed precision location data into said calibration subscriber unit.

5. A method as recited in claim 1, further comprising the steps of:

associating said measured signal parameters and said precision location data at said calibration subscriber unit; and

transmitting said measured signal parameters and said precision location data to said satellite from said calibration subscriber unit.

6. A method as recited in claim 1, wherein step (d) comprises the steps of:

(d1) generating a satellite access request message containing said measured signal parameters and said precision location data at said satellite; and

(d2) transmitting said satellite access request message to said gateway by said satellite.

7. A method as recited in claim 1, wherein step (e) further comprises the steps of:

(e1) generating a calibration record containing said measured signal parameters and said precision location data by said gateway; and

(e2) analyzing said calibration record by said gateway.

8. A method as recited in claim 7, further comprising the step of concurrently completing a geolocation process using said measured signal parameters and said precision location data.

9. A method as recited in claim 7, further comprising the step of distributing said variance data to other gateways to be used to correct future geolocations through said satellite involving said other gateways.