GPS Receiver Time Correction Using Partial Satellite Data

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Solution Overview

Problem

GPS reception apparatuses face challenges in accurately calculating the current position and obtaining correct time in environments with poor satellite signal reception, leading to high power consumption and reduced operation time, especially in portable devices.

Innovation Solution

The apparatus determines a predetermined reception state based on satellite information and calculates the current position using ephemeris and almanac information from a subset of satellites, allowing for time correction based on stored district information, even in environments with inadequate signal reception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the GPS reception apparatus repeatedly operates to receive GPS signals and obtain ephemeris information, then the accuracy of current position calculation is improved, but power consumption increases significantly

Engineering Contradiction:

Improveaccuracy of current position calculationVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The apparatus performs preliminary determination of reception state using satellite information before fully processing ephemeris data. By pre-assessing whether the reception environment is suitable for accurate positioning, the system avoids unnecessary repeated signal reception operations, thereby reducing power consumption while maintaining positioning accuracy when conditions permit

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The apparatus uses partial satellite information (at least three satellites) instead of requiring full ephemeris data from multiple satellites. This partial action approach allows the system to determine current position with sufficient accuracy using fewer satellites, reducing the time and energy required for signal reception and processing

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If the GPS reception apparatus repeatedly operates to receive GPS signals, then the reliability of obtaining ephemeris information is improved, but the continuous operation time is reduced

Engineering Contradiction:

Improvereliability of obtaining ephemeris informationVSAvoidcontinuous operation time

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The apparatus preliminarily determines whether the current reception state is suitable for obtaining reliable ephemeris information before initiating full signal reception operations. This pre-assessment using satellite information allows the system to avoid unnecessary repeated operations in poor reception environments, thereby extending continuous operation time while maintaining reliability when conditions are favorable

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The apparatus uses its own received satellite information to determine reception state and make decisions about whether to proceed with full ephemeris processing. This self-service approach eliminates the need for external intervention or repeated manual operations, allowing the system to autonomously extend its continuous operation time while maintaining reliable positioning when possible

Inventive Principle:

Principle #25Self-service

3Measurement precision

If the GPS reception apparatus uses standard time correction methods, then the accuracy of current time is improved, but the complexity of time zone determination is increased

Engineering Contradiction:

Improveaccuracy of current timeVSAvoidcomplexity of time zone determination

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The apparatus creates a simplified model of time zone determination by using stored district information as a reference copy. Instead of complex real-time time zone calculation, the system compares current position with pre-stored district data to determine time zone, reducing computational complexity while maintaining time accuracy

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The apparatus uses simple, pre-stored district information (such as time zone offsets) instead of complex, real-time time zone calculation algorithms. This approach uses inexpensive, easily stored data to achieve accurate time correction without requiring complex processing, thereby reducing device complexity

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS8848490B2GPS reception apparatus and positional calculation method for the same

Publication Date: 2014.09.30 CASIO COMPUTER CO LTD

AI summary

A reception apparatus includes a first determination unit to determine whether a state exists in which timing information and six orbital elements information can be obtained from GPS signals transmitted by only two GPS satellites. When the state exists, a calculation unit calculates a trajectory line having a predetermined width on a surface of the earth, based on the GPS signals transmitted by the two satellites. A second determination unit determines whether the trajectory line traverses a district of use stored by the apparatus. A time correcting unit obtains a current time using the obtained timing information, by correcting the timing information based on a time zone corresponding to the district of use, when the trajectory line traverses the district of use. The time correcting unit does not obtain the current time using the obtained timing information when the trajectory line does not traverse the district of use.