Phase Correction Circuit for Stable Distance Measurement Timing

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Solution Overview

Problem

The existing phase detection methods for distance measurement in keyless entry systems, particularly those using a digitally controlled oscillator (DCO) direct modulation method for transmission and a sliding IF method for reception, suffer from fluctuations in the reference time phase, leading to inaccurate distance measurement due to the independent operation of reference signals, which affects not only distance measuring devices but also other devices using local oscillators.

Innovation Solution

A phase correction device with an all-digital phase-locked loop is introduced to generate local oscillation signals and correct the phase of inputted signals by calculating the difference between phase values at predetermined timings, allowing for accurate distance measurement by stabilizing the reference time phase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a DCO direct modulation method is used for transmission and a sliding IF method is used for reception to reduce power consumption, then power consumption is reduced, but the reference time phase fluctuates in the local oscillator, deteriorating distance measurement accuracy

Engineering Contradiction:

Improvepower consumptionVSAvoiddistance measurement accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the phase detector continuously monitors the phase difference between the transmitted signal and the local oscillation signal, and the DCO adjusts its output phase based on this feedback to maintain a constant phase relationship, thereby stabilizing the reference time phase while maintaining low power consumption operation

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the operating parameters of the DCO, specifically adjusting its output frequency and phase based on the detected phase error, allowing the system to maintain accurate distance measurement by compensating for phase fluctuations while operating in the low-power sliding IF mode

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If reference signals operate independently in each device for distance measurement, then device complexity is reduced and ease of operation is improved, but distance measurement accuracy is greatly deteriorated due to differing reference time phases

Engineering Contradiction:

Improveease of implementationVSAvoiddistance measurement accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a phase detector as an intermediary component that measures the phase difference between independently operating reference signals, and a DCO-based phase correction system that acts as a mediator to adjust the local oscillation signal's phase, thereby enabling accurate distance measurement while maintaining independent operation of reference signals in each device

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the need for synchronized mechanical timing systems with an electronic phase detection and correction mechanism, where the phase detector electronically measures phase differences and the DCO electronically adjusts timing, eliminating the need for complex mechanical synchronization while maintaining measurement accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This solution enables accurate distance measurement by stabilizing the reference time phase, improving the accuracy of phase detection and reducing power consumption, thus enhancing the security and efficiency of keyless entry systems against relay attacks.

Implementation Method 1

a local oscillator including an all digital phase-locked loop that generates a plurality of kinds of local oscillation signals based on a reference clock

Methodology Applied

Scientific EffectPhase-locked loop:

Data Source

PatentUS12196853B2Phase correcting device and distance measuring device

Publication Date: 2025.01.14 KK TOSHIBA

AI summary

A phase correcting device of an embodiment includes a local oscillator that includes an all digital phase-locked loop configured to generate a plurality of kinds of local oscillation signals based on a reference clock, and is configured to give one of the local oscillation signals to a device configured to detect a phase of an inputted signal, a phase detector configured to acquire and output, at a predetermined timing, an output of a phase integrator included in the all digital phase-locked loop, and a phase calculator configured to acquire, a plurality of times at predetermined timings, values outputted from the phase detector and correct the phase of the inputted signal by using a difference between the values.