Signal Conditioning for Resonator Fiber Optic Gyroscope Gain
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Solution Overview
Problem
Conventional resonator fiber optic gyroscope (RFOG) systems face challenges in achieving high performance due to limitations in signal resolution and noise rejection, particularly with conventional analog-to-digital converters (ADCs), which struggle to digitize small rotation signals in the presence of large unwanted harmonic signals, leading to errors and reduced gain.
Innovation Solution
A signal-conditioning circuit is introduced that splits the gyro signal into two paths, applying filters optimized for unwanted signal rejection and noise passing, allowing for additional gain and noise necessary for ADC bit interpolation, using notch filters to attenuate even harmonics and passing odd harmonics and noise above the 19th harmonic to enhance ADC processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ADCs are used to digitize the gyro signal, then the system is simple and low-cost, but the signal resolution is insufficient due to the presence of large harmonic signals
Solution Approach 1:
The patent applies preliminary filtering action before the ADC conversion process. Notch filters are positioned upstream in the signal chain to attenuate even harmonics before they can interfere with the ADC quantization process. This preliminary removal of harmful frequency components enables conventional ADCs to achieve higher effective resolution without requiring complex high-resolution converters.
2Measurement precision
If filters are added to remove unwanted harmonic signals, then signal resolution improves, but device complexity increases
Solution Approach 1:
The patent applies local quality by using targeted notch filters at specific harmonic frequencies rather than broad-spectrum filtering. Each notch filter is precisely tuned to remove only the problematic even harmonics (2nd, 4th, 6th, etc.) while preserving the fundamental gyro signal and odd harmonics. This selective local filtering achieves high signal resolution with minimal circuit complexity.
3Measurement precision
If gain is increased to amplify the small rotation signal, then measurement precision improves, but noise is also amplified
Solution Approach 1:
The patent extracts and removes the harmful even-harmonic noise components through notch filtering before the amplification stage. By taking out these specific frequency components that would otherwise be amplified along with the signal, the system can apply higher gain to the rotation signal without proportionally amplifying the harmful harmonics, thus improving measurement precision while controlling noise.
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 approach significantly improves signal gain and reduces angle random walk (ARW) by effectively rejecting unwanted signals and noise, enabling higher precision in rotation sensing and navigation applications.
Implementation Method 1
A filtering element is configured to attenuate the DC signal, at least one even-harmonic component, and an odd-harmonic component to produce a second electrical signal
Implementation Method 2
An amplifier is configured to amplify the second electrical signal
Implementation Method 3
An analog-to-digital converter (ADC) is configured to digitize the amplified second electrical signal
Data Source
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AI summary
A resonator fiber optic gyroscope includes a first light source configured to generate a light signal. A resonator element is configured to generate a optical signal based on the light signal. A photodetector is configured to generate a first electrical signal based on the optical signal. The first electrical signal includes an oscillating signal, a direct-current (DC) signal, an even-harmonic signal including components at even harmonics of the oscillating signal, and an odd-harmonic signal including components at odd harmonics of the oscillating signal. A filtering element is configured to attenuate the DC signal, at least one even-harmonic component, and an odd-harmonic component to produce a second electrical signal. An amplifier is configured to amplify the second electrical signal. An analog-to-digital converter (ADC) is configured to digitize the amplified second electrical signal.