Precision analog demodulation technique for open-loop Sagnac fiber optic gyroscopes

Area of Science:

• * Optical Engineering
• * Sensor Technology
• * Signal Processing

Background:

• * Interferometric fiber optic gyroscopes (IFOGs) are crucial for navigation and guidance systems.
• * Traditional demodulation techniques, like lock-in amplifiers, face limitations in signal-to-noise ratio (SNR) and complexity.
• * Accurate signal demodulation is essential for detecting small angular displacements.

Purpose of the Study:

• * To develop and validate a new analog signal processing technique for demodulating IFOG signals.
• * To compare the performance of the novel technique against established methods, specifically lock-in amplifiers.
• * To assess the temperature stability and sensitivity of the developed demodulator circuit.

Main Methods:

• * An analog circuit was designed to calculate the mean value of negative cycles from sinusoidally modulated Sagnac gyroscope signals.
• * The developed circuit was implemented and tested in a laboratory setting.
• * Performance evaluation involved measuring minimum detectable signals and comparing SNR with a lock-in amplifier.

Main Results:

• * The novel analog demodulator successfully detected signals as low as 5 microrad.
• * Experimental results demonstrated a 5.1 dB higher signal-to-noise ratio compared to the lock-in amplifier technique.
• * The circuit exhibited excellent temperature stability, with a measured drift of 0.04 degrees/hour/°C.

Conclusions:

• * The proposed analog demodulation technique offers a significant improvement in SNR for IFOGs.
• * The circuit's high sensitivity, stability, and improved SNR make it a viable alternative to existing methods.
• * The technology is being integrated into the Brazilian VSB-30 sounding rocket, highlighting its practical application potential.