GPS interference: keep ships on the strait and narrow

The University of Nottingham and the Royal Norwegian Naval Academy (RNoNA) are investigating how to prevent Global Positioning Signals (GPS) location from being blocked in the event of potential cyberattacks that could cause ships to deviate from course and collide or on Basic run.

Large, modern ships are highly automated with networked navigation systems, including differential GPS (DGPS), which provides more accurate positioning (up to a meter) than traditional GPS.

However, previous research has shown that these highly sensitive marine DGPS receivers are easy to jam when using £ 50 worth of signal blocker which are widely available in the market.

An interruption of the DGPS signal, especially when ships are sailing through narrow coastal waters, can lead to inaccurate position information and lead to more marine accidents.

For the study, scientists from the Nottingham Geospatial Institute (NGI) and the RNoNA Navigation Center tested the DGPS disruption on the busy shipping lanes of the Norwegian Strait, where navigation errors make up half of the accidents.

Dr. Lukasz Bonenberg, chief technical officer at NGI, said: “The main contributors to marine casualties in this part of Norway are the influx of foreign ships, combined with rapidly changing weather conditions and the dangers of the narrow coastal waters.

“In these difficult conditions, where highly accurate navigation is required, there tends to be an over-reliance on DGPS technology, which can create a false sense of security. These errors have increased significantly since DGPS was introduced on most ships.

“DGPS congestion from nearby cliffs, for example, could seriously affect shipping traffic through the narrow straits and fjords. Affected ships could take a long time to correct their voyage or physically stop, which can create the maritime equivalent of a highway pile,” adds Dr . Bonenberg added.

The experiment was conducted with the high-end survey receiver and antenna placed on the bank with the handheld gps jammer moving towards or away from the receiver on a small boat.

The aim of the experiment was to quantify the disturbance effect and to simulate the approach of a ship to a narrow coastal road. The researchers found that the DGPS receiver didn’t stop working entirely. Instead, there were incorrect readings in the on-board navigation system with position data that moved more than 10 meters.

“Observed deviations of up to 10 meters are very dangerous given the narrow nature of the Norwegian Straits, which are often affected by poor visibility,” explains Lieutenant Commander Oeystein Glomsvoll of the RNoNA Navigation Center.

“GSM signal jammer is a growing problem around the world. Interference technology is readily available, which has resulted in deliberate interference in many cases in recent years, and the attention paid to this problem has increased.”

The research team was looking for a solution that would use additional GPS signal frequencies to pinpoint and maintain a transport ship’s position more accurately and quickly, rather than updating the navigation systems on board.

Currently, most marine receivers are DGPS L1 receivers. The authors propose to combine this system with the multi-frequency GLONASS receiver – an alternative navigation system to GPS.

This is because the frequency band of GPS + GLONASS signals taken together is much wider than double the L1 and L2 frequency GPS or GLONASS alone, which increases the position accuracy.

This is not only due to the increased number of satellites used, but also to the higher altitude and better coverage of the GLONASS satellites operated by the Russian aerospace forces.

Dr. Bonenberg of the Faculty of Engineering said, “Using receivers with multiple constellations and increasing the frequencies received provides better immunity for coastal navigation.”

GPS signaling is currently being modernized, including an additional frequency (L5) and an open L2C code on an L2 frequency. Currently, only a limited number of satellites offer these signals. The data observed during this experiment suggest that the use of this modernized signal offers similar benefits to the multi-frequency GLONASS signal.