Odd Harmonic PGC Modulation for Fiber Sensor Drive Voltage Reduction
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Solution Overview
Problem
Fiber optic sensor arrays face high power consumption and excessive drive voltage requirements due to high sampling rates, which are not efficiently addressed by existing demodulation algorithms, especially when using eight-point or sixteen-point FFT demodulation algorithms at lower PGC frequencies.
Innovation Solution
Implementing a phase generated carrier (PGC) frequency that is an odd harmonic of the usual PGC frequency, allowing for reduced drive voltage while maintaining equivalent performance, by using odd harmonic frequencies such as 3/8, 5/8, or 7/8 of the TDM signal sampling rate within the eight-point FFT demodulation algorithm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high sampling rates are used for fast interrogation of sensor pulses, then speed of signal processing is improved, but power consumption and drive voltage requirements increase excessively
Solution Approach 1:
The patent changes the PGC frequency parameter to odd harmonics (3/8, 5/8, 7/8 of sampling rate) instead of the conventional 1/8 frequency. This parameter transformation allows the system to achieve fast interrogation speeds while reducing the drive voltage requirements and power consumption, as the odd harmonic frequencies provide equivalent demodulation performance at lower power levels.
2Use of energy by moving object
If PGC frequency is reduced to lower power consumption, then energy use is improved, but drive voltage requirements become excessive
Solution Approach 1:
The patent transforms the PGC frequency parameter from conventional low frequencies to odd harmonic frequencies (3/8, 5/8, 7/8 of the sampling rate). This parameter change enables the system to operate at reduced power consumption levels while avoiding excessive drive voltage requirements, because the odd harmonic frequencies provide the necessary signal strength at lower power levels.
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 reduces power consumption and drive voltage requirements, enabling fast interrogation of sensor pulses with peak-to-peak voltages not exceeding 10-15 volts, while maintaining the performance of higher drive voltage scenarios, thus optimizing signal processing for fiber optic sensor arrays.
Implementation Method 1
a phase modulator for encoding the input optical signal with a phase generated carrier optical signal at a modulation frequency that is an odd harmonic of the frequency of the usual phase generated carrier
Data Source
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AI summary
A method and system for providing fast interrogation of a signal received from a fiber optic sensor array using a low drive voltage, by modulating the array signal with a phase generated carrier optical signal having a modulation frequency which is an odd harmonic of the usual phase generated carrier (PGC) frequency, sending it to an interferometric system, and demodulating the array signal using a demodulation algorithm that is independent of the phase offset. A detector using direct detection method can be used to determine the signal's phase information. The odd harmonic modulation method allows the selection of a desirable odd harmonic PGC frequency with low drive voltage while providing similar performance of the usual PGC frequency that requires a higher drive voltage.