Synchronous Fiber Optic Gyroscope Phase Lock Loop
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Solution Overview
Problem
Radiation-hardened fiber optic gyroscopes for harsh environments, such as outer space, face performance limitations due to the unavailability of high-speed radiation-hardened components, requiring asynchronous operation and lower performance, and lack of radiation-hardened direct digital synthesizers and high-speed digital-to-analog converters.
Innovation Solution
A synchronous fiber optic gyroscope design incorporating a phase lock loop that generates a high-frequency signal from a low-frequency signal using a radiation-hardened discrete direct digital synthesizer, enabling synchronous modulation and demodulation, and allowing for the use of radiation-hardened components while achieving high performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radiation-hardened components are used, then reliability in harsh environments is improved, but operating speed and performance deteriorate
Solution Approach 1:
A phase lock loop is introduced as an intermediary device between the low-speed radiation-hardened direct digital synthesizer and the high-speed demodulation circuitry. The PLL converts the low-frequency signal from the radiation-hardened synthesizer into a high-frequency signal that synchronizes with the system clock, enabling fast operation while maintaining compatibility with radiation-hardened components
Solution Approach 2:
The patent replaces the need for high-speed radiation-hardened direct digital synthesizers and high-speed digital-to-analog converters with an alternative architecture using a phase lock loop. This substitution allows the system to achieve high-speed operation through frequency conversion rather than relying on unavailable high-speed radiation-hardened components
2Reliability
If asynchronous operation is used with low-speed components, then reliability is improved, but demodulation sampling efficiency and performance deteriorate
Solution Approach 1:
The phase lock loop implements a feedback mechanism where the output signal is fed back and compared with the input signal to maintain phase and frequency lock. This feedback ensures that the modulated signal remains synchronous with the demodulation process, maximizing sampling efficiency and performance while using reliable radiation-hardened components
Solution Approach 2:
The system changes the frequency parameter of the signal through the phase lock loop, converting a low-frequency signal from the radiation-hardened synthesizer into a high-frequency signal that matches the system clock frequency. This parameter transformation enables synchronous operation and high demodulation sampling efficiency
3Speed
If high-speed commercial components are used, then operating speed is improved, but radiation hardness deteriorates
Solution Approach 1:
The system is segmented into distinct functional blocks: a radiation-hardened direct digital synthesizer operating at low speed, a phase lock loop for frequency conversion, and high-speed demodulation circuitry. This segmentation allows each component to be optimized for its specific function - radiation hardness for the synthesizer and speed for the demodulation - while the PLL bridges the gap between them
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 enhances demodulation sampling efficiency, reduces angle random walk and rate/angle white noise, and improves bias stability, enabling high-performance operation in harsh radiation environments.
Implementation Method 1
A phase lock loop has an input and an output, with the output of the phase lock loop operatively connected to the second input of the loop closure signal processor. A direct digital synthesizer is operatively coupled to the input of phase lock loop, with the direct digital synthesizer configured to generate a low-frequency signal that is transmitted to the phase lock loop. The phase lock loop converts the low-frequency signal to a high-frequency signal
Implementation Method 2
an optical modulator in optical communication with the optical coupler
Implementation Method 3
a detector configured to receive an optical signal from the optical coupler and convert the optical signal to an electrical signal
Implementation Method 4
a fiber optic coil in optical communication with the optical modulator
Data Source
Figure 1
Figure 2
AI summary
A synchronous fiber optic gyroscope includes a light source, an optical coupler in optical communication with the light source, an optical modulator in optical communication with the coupler, and a fiber optic coil in optical communication with the modulator. A detector is configured to receive an optical signal from the coupler and convert the optical signal to an electrical signal. A loop closure signal processor has a first input configured to receive the electrical signal from the detector. A phase lock loop has an output operatively connected to a second input of the processor. A direct digital synthesizer is operatively coupled to an input of the phase lock loop, with the synthesizer configured to generate a low-frequency signal that is transmitted to the phase lock loop. The phase lock loop converts the low-frequency signal to a high-frequency signal that is transmitted to the second input of the processor, and the phase lock loop provides signal modulation that is synchronous with signal demodulation.