Adaptive Oscillator Noise Cancellation for Vibration-Induced Phase Noise
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Solution Overview
Problem
Mechanical acceleration causes significant phase noise sidebands in electronic devices due to microphonics, affecting oscillators and propagating through systems, leading to errors in signal transmission and requiring costly mechanical isolation structures.
Innovation Solution
A system with a reference oscillator and an accelerometer on the same platform detects mechanical acceleration, generating a tuning control signal through an adaptive filter assembly with adjustable weights, which compensates for phase noise by comparing the oscillator output with an external signal, allowing for the use of lower-cost, non-ruggedized oscillators without increased noise or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanical isolation structures are used to protect the reference oscillator from vibration, then the oscillator noise performance is improved, but the system weight and cost increase significantly
Solution Approach 1:
The patent replaces mechanical isolation structures with an electronic compensation system. An accelerometer detects mechanical acceleration, and a digital filter processes this information to generate correction signals that compensate for microphonics effects on the oscillator, eliminating the need for heavy mechanical isolation
Solution Approach 2:
The patent introduces an accelerometer as an intermediary device that measures mechanical acceleration and provides this information to a digital filter, which then generates correction signals. This intermediary measurement approach allows electronic compensation without direct mechanical protection of the oscillator
2Reliability
If ruggedized oscillators are used to resist mechanical acceleration effects, then the oscillator stability is improved, but the cost and weight increase
Solution Approach 1:
The patent replaces expensive ruggedized oscillators with standard oscillators combined with electronic compensation. The digital filter processes accelerometer data to generate correction signals that maintain oscillator stability without requiring specialized ruggedized components
Solution Approach 2:
The patent uses inexpensive standard oscillators instead of expensive ruggedized ones, compensating for their vulnerability to mechanical acceleration through electronic correction. This allows the use of cheaper, easier-to-manufacture components while maintaining performance
3Measurement precision
If individual oscillator testing and calibration is performed to account for manufacturing variations, then the measurement precision is improved, but the productivity decreases
Solution Approach 1:
The patent implements continuous feedback from the accelerometer to the digital filter, which adjusts filter weights in real-time based on measured acceleration and oscillator output comparison. This feedback mechanism maintains precision without requiring time-consuming individual calibration
Solution Approach 2:
The system performs self-calibration by comparing the oscillator output with an external reference signal and automatically adjusting filter weights to minimize phase noise, eliminating the need for external testing and calibration equipment
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 effectively minimizes noise caused by mechanical acceleration, reducing the need for expensive mechanical isolation and accounting for minor variations among oscillators, while maintaining system accuracy and reducing testing time.
Implementation Method 1
an accelerometer on a same platform as the reference oscillator, such that mechanical acceleration at the reference oscillator is detected at the accelerometer to produce a measured acceleration
Implementation Method 2
A filter assembly, having an associated set of filter weights, receives the measured acceleration from the accelerometer and provides a tuning control signal responsive to the measured acceleration
Implementation Method 3
An adaptive weighting component receives the oscillator output signal of the reference oscillator and an external signal that is provided from a source external to the platform and adjusts the set of filter weights for the filter assembly based on a comparison of the external signal and the oscillator output signal
Data Source
AI summary
Systems and methods are provided for compensating for mechanical acceleration at a reference oscillator. A reference oscillator provides an oscillator output signal and an accelerometer on a same platform as the reference oscillator, such that mechanical acceleration at the reference oscillator is detected at the accelerometer to produce a measured acceleration. A filter assembly, having an associated set of filter weights, receives the measured acceleration from the accelerometer and provides a tuning control signal responsive to the measured acceleration to a frequency reference associated with the system. An adaptive weighting component receives the oscillator output signal of the reference oscillator and an external signal that is provided from a source external to the platform and adjusts the set of filter weights for the filter assembly based on a comparison of the external signal and the oscillator output signal.