Satellite Position Estimation via Doppler Shift Error Correction

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Solution Overview

Problem

Mobile user terminals in satellite communication systems face challenges in determining their position without continuous GPS signal availability, leading to loss of communication with satellites when GPS signals are blocked.

Innovation Solution

The system uses Doppler shift measurements from communication satellites to estimate the user terminal's position, eliminating the need for GPS signals by calculating the difference between expected and observed Doppler frequency offsets and correcting the local frequency reference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the user terminal uses GPS satellites to determine its position, then the position information can be obtained accurately, but the communication with the satellite is lost when GPS signals are blocked

Engineering Contradiction:

Improveposition information accuracyVSAvoidcommunication continuity

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces communication satellites as an intermediary to provide position information. Instead of relying solely on GPS satellites, the communication satellite transmits signals that contain position data, enabling the user terminal to determine its location through the communication satellite itself, thus maintaining communication continuity when GPS signals are unavailable

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The communication satellite performs multiple functions: it provides communication services and simultaneously provides position information. By making the communication satellite universal, the system eliminates the need for separate GPS satellites, allowing the same satellite to serve both communication and positioning purposes, thereby improving reliability when GPS is blocked

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If the user terminal constantly updates position information using GPS, then the position can be tracked accurately, but the system becomes dependent on GPS signal availability

Engineering Contradiction:

Improveposition tracking accuracyVSAvoidGPS signal dependency

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the fundamental parameter of position determination from GPS-based to communication satellite-based. By altering the source of position information from external GPS satellites to the communication satellite itself, the system adapts to environments where GPS signals are unavailable while maintaining position tracking capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The communication satellite serves itself by providing both communication and positioning functions. The satellite uses its own orbital information and the received signal characteristics to determine the user terminal's position, eliminating the need for separate GPS infrastructure and reducing dependency on external positioning systems

Inventive Principle:

Principle #25Self-service

3Loss of information

If the user terminal relies on ephemeris data from GPS satellites, then the orbital information can be obtained, but the position determination fails when GPS communication is lost

Engineering Contradiction:

Improveorbital information availabilityVSAvoidposition determination reliability

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The communication satellite acts as an intermediary that provides orbital and position information directly to the user terminal. Instead of relying on GPS satellites for ephemeris data, the communication satellite transmits its own orbital information, ensuring that position determination remains reliable even when GPS communication is lost

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables continuous satellite communication by determining the user terminal's position using signals from communication satellites, reducing dependency on GPS and maintaining communication even in areas where GPS signals are unavailable.

Implementation Method 1

a Doppler shift measuring portion measuring a Doppler shift Dm; a predetermined Doppler shift storage portion storing a predetermined received Doppler shift Dp; a received signal Doppler shift error calculating portion calculating a received signal Doppler shift error De

Methodology Applied

Scientific EffectDoppler shift: Doppler Effect

Data Source

PatentUS9164163B2System and method for estimating terminal position based on non-geostationary communication satellite signals

Publication Date: 2015.10.20 HUGHES NETWORK SYST

AI summary

A device is provided for use with a satellite and a receiver having a local oscillator. The satellite is traveling in a vector and transmits a signal having an expected frequency. The receiver receives a received signal having a received signal frequency. The device includes: a Doppler shift measuring portion measuring a Doppler shift Dm; a predetermined Doppler shift storage portion storing a predetermined received Doppler shift Dp; a received signal Doppler shift error calculating portion calculating a received signal Doppler shift error De; a predetermined receiver position storage portion storing a predetermined position Pp of the receiver; and a receiver position estimating portion calculating an estimated receiver position Pe based on the predetermined position Pp of the receiver and the received signal Doppler shift error De.