The GPS is in trouble. Once a miracle of navigation, GPS is now vulnerable to jamming and identity theft. Several countries, including China and Russia, have designed anti-GPS systems, from jammers to weapons targeting GPS satellites. Even civilians can buy GPS jammers of questionable legality.
Currently, the US military depends on GPS for precise navigation and – just as important – precise targeting of smart weapons. If the GPS is unreliable, the Pentagon will need a reliable substitute.
This is why the US Navy is looking for a substitute for GPS: use the Earth’s magnetic field for navigation. The project – called Positioning Using Magnetic Anomalies Correlation of Earth (PUMACE) – used anomalies in the Earth’s magnetic field to determine location.
“GPS uses weak radio frequency (RF) signals from distant satellites and is subject to intentional and unintentional interference,” says the Navy’s research solicitation. “Navigation based on the Earth’s magnetic field promises more robust all-weather passive navigation, without reliance on new infrastructures. “
The Navy wants a magnetic sensor for ships and submarines that is accurate to at least 30 meters (32.8 feet) and ideally 15 meters (16.4 feet). It should weigh less than 15 pounds and use less than 5 watts of power.
The Air Force Institute of Technology has previously tested magnetic anomaly navigation, in which scalar magnetometric sensors measure differences in the magnitude of magnetic fields as the sensor passes them, and then compare those readings with known readings on field maps. magnetic. Animals such as turtles and birds seem to already use some form of magnetic navigation.
However, the Navy wants to further refine the process. “Challenges remain regarding the availability of accurate maps of the earth’s crustal magnetic field,” noted the Navy’s solicitation. “The presence of larger base fields, as well as temporal variations, can further limit the accuracy of positional accuracy. In addition, the magnetic fields induced locally by the ship itself must also be taken into account in determining the position.
Models of the Earth’s magnetic field tend to focus on the field generated by the core of our planet, rather than the earth’s crust. “The detection of the variation of the crustal field could allow precise positioning; However, because the crustal field is so small compared to the main fields, it also requires advanced vector sensors, ”the Navy said. “Current generation sensors are limited because they are scalar sensors and therefore unable to detect minute variations in the Earth’s crustal field.”
PUMACE aims to develop a system that is sufficiently precise and reliable to assist and correct any errors in inertial navigation systems (INS), which also operate independently of GPS. This family of sensors may promise robust positioning using integrated systems capable of mixing data from alternative positioning sensors as an INS reset for continuous and accurate navigation on the platform without reliance on GPS. “said the Navy. “In addition to using the INS, the data can be used as another sensor source for integrity assessment within the Position, Navigation and Timing (PNT) suite.”
Phase I of the project consists of determining the feasibility of measuring anomalies in the Earth’s magnetic field, and the sensors required for this. Phases II and III will include the development of technical specifications and a working prototype.
Whether or not PUMACE succeeds, the US military will need to find jam-proof alternatives to GPS. Not only do precision-guided weapons require a precise navigation system, so does the American mode of warfare, which depends on the close and precise coordination of air, land, sea and space forces separated by great distances. . American adversaries are well aware of this vulnerability and will seek to exploit it.
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