Satellite Receiver TTFF Reduction via Time Feedback

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Solution Overview

Problem

Satellite radiowave receiving devices experience inaccuracies in determining the current position due to incorrect date and time information, leading to prolonged Time to First Fix (TTFF) in positioning calculations, even when preliminary positional information is retained.

Innovation Solution

The device modifies date and time information by obtaining it from a single positioning satellite after starting the positioning operation and uses this updated information along with preliminarily retained positional data for accurate positioning calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If preliminary positional information on positioning satellites is retained from external servers, then the time to obtain satellite positional information is reduced, but inaccurate date and time information causes inaccurate satellite position calculation, resulting in prolonged Time to First Fix

Engineering Contradiction:

ImproveTime to obtain satellite positional informationVSAvoidAccuracy of satellite position calculation

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The device performs preliminary acquisition of satellite positional information (ephemeris data) from external servers before positioning is needed. This pre-loaded data is stored in memory and can be quickly accessed when positioning starts, eliminating the need to download this data in real-time and thus reducing the Time to First Fix.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The device continuously monitors and updates its date and time information by receiving timing signals from positioning satellites. This accurate time information serves as feedback to correct and refine the calculation of satellite positions, ensuring that even though preliminary data is used, the final position calculation remains accurate by iteratively adjusting based on real-time satellite timing information.

Inventive Principle:

Principle #23Feedback

2Productivity

If preliminary positional information is retained to reduce TTFF, then initial positioning speed is improved, but inaccurate date and time causes convergence to inaccurate position, requiring longer time to achieve accurate positioning

Engineering Contradiction:

ImproveInitial positioning speedVSAvoidAccuracy of initial position determination

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The device pre-loads satellite ephemeris data from external servers before positioning operations begin. This preliminary data provides immediate satellite position information that can be used right away when positioning starts, enabling fast initial positioning without waiting for data download during the positioning process.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The device uses real-time timing information received from positioning satellites as feedback to continuously refine and correct the calculated position. This feedback mechanism ensures that the initial quick position estimate is progressively improved to achieve accurate convergence, resolving the contradiction between speed and accuracy.

Inventive Principle:

Principle #23Feedback

3Use of energy by moving object

If date and time information is not accurately maintained, then power consumption is reduced by not continuously synchronizing, but positioning calculation accuracy deteriorates due to inaccurate satellite position determination

Engineering Contradiction:

ImprovePower consumption for time synchronizationVSAvoidPositioning calculation accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The device maintains its date and time information using an internal clock that operates autonomously without requiring continuous external synchronization. The clock is sufficiently accurate for the device's needs, eliminating the power consumption associated with continuous time synchronization while still providing accurate enough time information for positioning calculations.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The device periodically receives timing information from positioning satellites to correct and update its internal clock. This feedback-based time correction ensures that the internally maintained time remains accurate enough for positioning purposes without requiring continuous synchronization, thus balancing power consumption with positioning accuracy.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11726434B2Satellite radiowave receiving device, electronic timepiece, positioning control method, and recording device

Publication Date: 2023.08.15 CASIO COMPUTER CO LTD

AI summary

A satellite radiowave receiving device includes a receiver receiving radiowaves transmitted from a positioning satellite; and a processor performing a positioning operation using the radiowaves received by the receiver. If the receiver starts receiving radiowaves for the positioning operation, the processor obtains date and time information based on radiowaves received from a single positioning satellite after the receiver starts receiving radiowaves. The processor preforms a positioning calculation using the obtained date and time information and preliminarily retained positional information on the positioning satellite.