Segmented Optical Drive Circuit for Fiber Gyro Deadband Reduction
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Solution Overview
Problem
Fiber optic gyros face limitations in precision due to data truncation errors, particularly at low rotation rates, leading to deadband errors and reduced sensitivity, which are exacerbated by the use of single high-resolution DACs that require truncation, resulting in unwanted noise and decreased system throughput.
Innovation Solution
The optical drive circuit employs a segmented digital-to-analog conversion process, separating data into most significant and least significant bits for parallel conversion and amplification, eliminating the need for truncation and enhancing resolution to at least 16-bit precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single high-resolution DAC is used to drive the optical circuit, then the converter resolution is improved, but data truncation errors occur leading to deadband errors and reduced measurement precision
Solution Approach 1:
The patent divides the digital signal into multiple segments (first digital signal portion and second digital signal portion) that are converted by separate DACs. This segmentation allows each DAC to operate at lower resolution while maintaining overall high precision through the combination of segments, eliminating the need for truncation that occurs with single high-resolution DACs.
2Device complexity
If data truncation is applied to reduce signal complexity, then the device complexity is reduced, but deadband errors and quantization noise increase
Solution Approach 1:
The patent segments the digital signal and processes each segment separately through dedicated DACs and amplifiers. This approach maintains signal integrity without requiring truncation, thereby eliminating deadband errors and quantization noise while keeping device complexity manageable through modular signal processing paths.
3Device complexity
If a single DAC is used to simplify the circuit, then the device complexity is reduced, but the output resolution and measurement accuracy deteriorate
Solution Approach 1:
The patent employs multiple DACs that process different segments of the digital signal in parallel. Each DAC operates at reduced resolution individually, but the combined output achieves high resolution equivalent to or exceeding a single high-resolution DAC, while simplifying individual circuit components and reducing overall complexity.
Solution Approach 2:
The patent combines the analog outputs from multiple DACs and their respective amplifiers to produce a composite analog signal that drives the optical circuit. This merging of multiple lower-resolution signals achieves the equivalent of a high-resolution signal without requiring a single complex high-resolution DAC.
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 reduces deadband errors and increases the output resolution of the optical drive circuit, improving the accuracy and reliability of rotation rate measurements by maintaining higher precision without introducing unwanted noise.
Implementation Method 1
The optical phase modulator may be operated in a feedback loop from the photodetection system to provide sufficient negative feedback for canceling the phase shift difference
Implementation Method 2
both ultimately impinge on a photodetector (e.g., a photodiode electrically coupled to a photodetection system)
Implementation Method 3
glass-based optical fibers that conduct light along a solid glass core of the fiber
Implementation Method 4
The difference in the two optical path lengths introduces a phase shift between the light beams for either rotation direction (i.e., the Sagnac effect), and this difference is proportional to the rotational rate
Data Source
AI summary
Systems and methods for improving output resolution of an optical drive circuit in an optical sensor. The optical sensor circuit includes an optics circuit that generates analog measurement data, a detector circuit that detects the analog measurement data and converts the analog measurement data to a digital measurement data, and a signal processing circuit that demodulates the digital measurement data and generates a segmented digital signal based on the demodulated digital measurement data. The optical sensor circuit further includes an optics drive circuit that generates an analog drive signal based on the segmented digital signal. The analog drive signal is then used to drive the optical circuit.