Adaptive Oscillator Compensation for Microphonics Noise
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Solution Overview
Problem
Mechanical acceleration causes phase noise sidebands in electronic devices due to microphonics, affecting oscillators and propagating through systems, leading to significant errors in communications systems, especially in piezoelectrical crystals, which existing technologies have not adequately addressed.
Innovation Solution
A system that includes a reference oscillator with an accelerometer to detect mechanical acceleration, generating a tuning control signal using an adaptive filter assembly with adjustable weights, which compares the oscillator output signal with an external signal to minimize noise caused by mechanical acceleration, allowing for the use of lower-cost, non-ruggedized oscillators without increased noise or weight, and compensating for minor variations among oscillators.
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 microphonic noise is reduced, but device weight and cost increase significantly
Solution Approach 1:
The patent replaces mechanical isolation structures with an electronic compensation system consisting of an accelerometer, digital signal processor, and feedback control mechanism. The accelerometer detects mechanical acceleration, the DSP processes the signal and calculates compensation values, and these values are fed back to adjust the oscillator frequency, thereby eliminating the need for heavy mechanical isolation while achieving the same noise reduction effect
Solution Approach 2:
The patent introduces an intermediary electronic system between the mechanical vibration source and the oscillator. The accelerometer acts as a sensor intermediary that detects vibration, and the digital signal processor acts as a computational intermediary that translates vibration data into frequency compensation values, which are then applied to the oscillator to cancel out microphonic effects
2Object-affected harmful factors
If mechanical isolation structures are used to protect the reference oscillator from vibration, then microphonic noise is reduced, but device cost increases significantly
Solution Approach 1:
The patent replaces expensive mechanical isolation structures (such as vibration isolation tables, damping mounts, and rigid enclosures) with a cost-effective electronic compensation system using standard accelerometers and digital signal processing, thereby achieving the same performance at lower manufacturing cost
Solution Approach 2:
The patent changes the approach from passive mechanical parameter optimization (mass, damping coefficients, stiffness) to active electronic parameter adjustment (filter coefficients, feedback gains, frequency correction values), allowing for lower-cost implementation while maintaining performance
3Object-affected harmful factors
If ruggedized oscillators are used to resist mechanical acceleration, then microphonic noise is reduced, but device weight and cost increase
Solution Approach 1:
The patent replaces ruggedized mechanical oscillator designs with a standard oscillator combined with an electronic compensation system, thereby reducing device complexity while achieving equivalent or superior performance in resisting microphonic noise
Solution Approach 2:
The patent implements a self-correcting system where the oscillator's own vibration-induced frequency deviations are detected by the accelerometer and automatically compensated through feedback control, eliminating the need for inherently ruggedized designs
4Measurement precision
If filter weights are made adaptive to account for oscillator response changes, then noise cancellation accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent implements dynamic adaptation of filter weights based on real-time oscillator response characteristics. The system continuously monitors the oscillator's frequency deviation under vibration and adjusts the filter coefficients accordingly, transitioning from static to dynamic compensation to maintain optimal noise cancellation accuracy under varying conditions
Solution Approach 2:
The patent employs feedback mechanisms where the oscillator output is monitored, compared against the expected output, and the error signal is used to adjust the filter weights. This closed-loop adaptation ensures accurate noise cancellation while managing computational complexity through efficient algorithms
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
Effectively reduces microphonic noise in communications systems by continuously adapting to changes in the response of the reference oscillator to mechanical acceleration, ensuring stable signal quality without the need for costly mechanical isolation structures.
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
Piezoelectrical crystals can be particularly vulnerable to this effect, and mechanical vibration can transiently change the resonant frequency of the crystal and introduce significant phase noise sidebands through inadvertent frequency modulation
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.