Quartz Frequency Reference Using PLL to Eliminate Micro-Hops

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Solution Overview

Problem

Quartz oscillators used in frequency reference systems, particularly in GNSS applications, are prone to frequency micro-jumps due to temperature variations, which are unpredictable and difficult to compensate for, leading to signal loss even with small frequency deviations, and existing solutions either have drawbacks such as frequency micro-jumps, high consumption, or complex implementation.

Innovation Solution

A system that includes a primary quartz oscillator and an auxiliary oscillator without micro-jumps, using alternative resonator technology, where the auxiliary oscillator is slaved to the primary oscillator to provide frequency stability and detect micro-jumps, with a feedback loop and phase-locked loop configuration to compensate for frequency deviations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a quartz oscillator is used to provide frequency reference, then precision and spectral purity are achieved, but frequency micro-jumps occur due to temperature sensitivity

Engineering Contradiction:
Improvefrequency precisionVSAvoidfrequency stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a mediator component (temperature compensation mechanism or digital correction unit) that intervenes between the temperature variations and the quartz oscillator output. This intermediary detects temperature changes or frequency deviations and applies compensatory adjustments, thereby eliminating the direct harmful effect of temperature sensitivity while preserving the oscillator's precision and spectral purity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If temperature compensation is applied to reduce frequency variations, then temperature stability improves, but frequency micro-jumps still occur

Engineering Contradiction:
Improvetemperature stabilityVSAvoidfrequency continuity
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent implements a feedback mechanism that continuously monitors the oscillator output for frequency micro-jumps and applies real-time corrections. The feedback loop detects deviations caused by micro-jumps and adjusts the frequency reference accordingly, thereby maintaining frequency continuity even when temperature compensation alone is insufficient to eliminate micro-jumps.

Inventive Principle:
Principle #23Feedback

3Reliability

If sorting procedures are used to select oscillators without micro-jumps, then reliability improves, but manufacturing complexity and cost increase

Engineering Contradiction:
Improveabsence of micro-jumpsVSAvoidmanufacturing simplicity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent enables the oscillator system to self-correct frequency micro-jumps through integrated detection and compensation mechanisms. Rather than relying on manual sorting procedures during manufacturing, the system autonomously identifies and corrects micro-jumps in real-time operation, thereby achieving high reliability without increasing manufacturing complexity or cost.

Inventive Principle:
Principle #25Self-service

4Productivity

If wide servo loops are used during acquisition, then signal acquisition is improved, but tracking robustness decreases

Engineering Contradiction:
Improvesignal acquisition speedVSAvoidtracking robustness
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent employs dynamic adjustment of servo loop bandwidth based on operational phase. During signal acquisition, wide bandwidth loops enable rapid signal capture. During tracking phase, the system dynamically narrows the bandwidth to improve robustness against interference and frequency variations. This dynamic adaptation allows the system to optimize performance for each operational stage without compromising either acquisition speed or tracking robustness.

Inventive Principle:
Principle #15Dynamics

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

The system provides a frequency reference that is free from micro-jumps while maintaining the precision and stability of quartz oscillators, allowing for detection and compensation of frequency micro-jumps, thereby improving signal continuity and reliability in GNSS applications.

Implementation Method 1

a feedback loop which includes an auxiliary oscillator not subject to frequency micro-jumps, the reference frequency of the quartz oscillator being delivered to the feedback loop for slaving the auxiliary oscillator on the frequency reference of the primary quartz oscillator

Methodology Applied
Scientific EffectPhase-locked loop:

Implementation Method 2

These oscillators use a quartz crystal which has remarkable resonance characteristics, which makes it possible to meet the constraints of stability and spectral purity required by modern communications systems

Methodology Applied
Scientific EffectResonance: Resonance

Implementation Method 3

Quartz oscillators are components widely used in the electronics industry to serve as a frequency or time reference. These oscillators use a quartz crystal which has remarkable resonance characteristics, which makes it possible to meet the constraints of stability and spectral purity required by modern communications systems. On the other hand, the quartz crystal remains intrinsically very sensitive to temperature variations, thus impacting the stability of the oscillator that uses it

Methodology Applied
Scientific EffectTemperature compensation:

Data Source

PatentEP2599225B1Frequency reference system that is not adversely affected by frequency micro-hops
Publication Date: 2019.08.28 SAFRAN ELECTRONICS & DEFENSE SAS
  • EP2599225B1 patent drawingFigure 1
  • EP2599225B1 patent drawingFigure 2
  • EP2599225B1 patent drawingFigure 3

AI summary

The invention relates to a system for providing a reference frequency, including a primary quartz oscillator (1) that provides a reference frequency, characterized in that said system comprises: a feedback loop (10) including an auxiliary oscillator that is not subjected to frequency micro-hops (13), wherein the reference frequency is fed to the feedback loop in order to impart the reference frequency of the primary oscillator to the auxiliary oscillator; and an output (JFPO) from the auxiliary oscillator (13) to which the reference frequency of the primary oscillator is imparted.