Fiber Optic Sagnac Interferometer Quantization Noise Compensation
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Solution Overview
Problem
Fiber optic Sagnac interferometers face challenges in achieving high-precision yaw rate measurements due to noise from digital/analog converters, particularly at low yaw rates, which impede accurate rotation rate determination.
Innovation Solution
The implementation of a fiber optic Sagnac interferometer with a light source, polarizer, fiber coil, photodetector, amplifier, analog/digital converter, digital/analog converter, evaluation circuit, adder, and phase modulator, where a residual value signal is generated and used to compensate for quantization noise by incorporating excess bits as a phase error correction, effectively reducing noise and enhancing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a digital/analog converter is used in the fiber optic Sagnac interferometer, then the system can process and modulate signals, but quantization noise is introduced that degrades measurement precision at low yaw rates
Solution Approach 1:
The patent implements a feedback mechanism where the residual value signal from the analog/digital converter is fed back through an adder to compensate for quantization noise. The residual value, which contains information about the quantization error, is used to generate a correction signal that is added to the original signal, thereby reducing the impact of quantization noise on measurement precision.
Solution Approach 2:
The patent introduces an intermediary approach by using the residual value signal as a mediator between the analog/digital converter and the final measurement output. This residual value acts as a carrier of quantization noise information that can be processed and used to correct the measurement, allowing the system to maintain precision despite the presence of the digital/analog converter.
2Measurement precision
If the word length of the digital signal is increased to reduce quantization noise, then measurement precision improves, but device complexity and processing requirements increase
Solution Approach 1:
The patent applies partial action by using only the necessary portion of the residual value signal (the excess bits) to compensate for quantization noise. Instead of requiring the full high-word-length signal throughout the entire processing chain, the system uses only the residual value information where it is most needed - in the compensation feedback path - thereby reducing overall complexity while maintaining precision.
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 configuration allows for high-precision yaw rate measurements even at low yaw rates by completely or almost completely compensating for quantization noise, thereby improving the accuracy of rotation rate determination.
Implementation Method 1
This uses the Sagnac effect, according to which a phase difference occurs between two light waves running in opposite directions in the light guide loop when an optical light guide loop rotates about its normal.
Implementation Method 2
a photodetector device, an amplifier with a downstream analog/digital converter
Data Source
Figure 1
AI summary
In a fiber-optic Sagnac interferometer, the output of an analog-to-digital converter 2, and thus the output signals processed in a main control loop, as well as a phase reset signal for phase modulation, each have a first word width. An input of a digital-to-analog converter 3, and thus a reset signal applied to the phase modulator, has a second word width, which is smaller than the word width used to calculate the reset and modulation signals. A residual signal with a third word width is derived from the excess, low-order bits and can be added to the output signal of the analog-to-digital converter via an adder.