A NEW GENERATION OF FOG
Fiber Optic Gyroscopes (FOG) have long been trusted by the Marine industry. The first generation of FOG made available in 1976 used analog signals. The second generation, developed in 1994 and still used to this day, improved upon this with a hybrid approach using an analog signal in the coil with digital signal processing.
In 2021, FOG evolved into DFOG (Digital Fiber Optic Gyroscope). This third generation of FOG sets itself apart by being fully digital. The DFOG technology provides significantly lower SWaP-C (size, weight, power and cost), while providing industry leading accuracy and reliability. DFOG sets a new standard for gyro-compassing, motion reference units and inertial navigation.
DFOG, A DIGITAL REVOLUTION
DFOG is patent pending technology, which has been developed over 25 years across two research institutions together with Advanced Navigation. DFOG was created to meet the demand for smaller and more cost-effective FOGs while achieving maximum accuracy and improved reliability.
To achieve this, three different, yet complimentary, technologies were utilized to improve the capabilities of FOG:
1.Digital Modulation Techniques: DFOG uses specially developed digital modulation techniques that pass spread spectrum signals through the optical coil. This allows in-run variable errors in the coil to be detected and corrected, increasing accuracy.
2.Revolutionary Optical Chip: Five discrete components that are present in a traditional FOG are combined into a single chip. The optical chip decreases errors while significantly increasing DFOG’s reliability since there are fewer sensitive components and fiber splices.
3.Specially Designed Optical Coil: DFOG employs a specially designed closed-loop optical coil, developed to take full advantage of the digital modulation techniques. The optical coil offers a high level of protection for the optical components from shock and vibration, thus increasing reliability.
The resulting combination of these three technologies results in a final product that is 40% smaller, lighter and lower powered than comparable products with a 30% reduction in price. All this while increasing reliability and accuracy.
The key technology that enabled a breakthrough came from gravitational research conducted by two universities. Advanced Navigation saw the potential of the technology and continued to develop it for commercial use, investing 100,000 hours into the development of the first DFOG, Boreas D90.
BOREAS D90, THE WORLD’S FIRST DFOG
Boreas D90 is a GPS-aided Inertial Navigation System (INS) that provides ultrahigh accuracy position, velocity and orientation under the most demanding conditions. It combines cutting edge DFOG technology with closed loop accelerometers and a dual antenna RTK GNSS receiver. These are coupled in a sophisticated fusion algorithm to deliver reliable navigation. The system features ultra-fast north seeking, acquiring and maintaining an accurate heading, even without GNSS.
The small form factor makes it perfectly suitable for ROV/AUV while the lower cost enables accurate dead reckoning for a greater number of vessels. Furthermore, applications that currently use unreliable magnetic heading or are heavily reliant on GPS, can now use gyro compassing.
This story was originally featured in ON&T Magazine’s June 2021 issue. Click here to read more.
