Since the launch of Sputnik in 1957, the skies above us have gradually filled with artificial satellites. Monitoring, communicating and observing. From predicting the weather forecast to looking out into deep space, we've come to rely on the information this network can provide us with. Perhaps of all the satellite systems, we depend most on the Global Positioning System (GPS), a radio navigation system that helps us locate, track and navigate.

GPS technology is used across our society and economy in transport, farming and law enforcement, and underpins banking transfers, digital maps and mobile phones. Any disturbance to this service would result in major disruption to our daily lives, and this has left us increasingly vulnerable to both natural space weather events and criminal activities.

Danger from solar flares

Storms on the surface of the sun can bombard the Earth with powerful radiation causing satellite signal loss and fading. Many of our satellites orbit in an area of our upper atmosphere known as the ionosphere, about 80km above the Earth's surface.

From the Arctic to Antarctica, we have gathered data using a network of GPS scintillation receivers and combine this with other information using algorithms that carry out complex signal-processing tasks, tomography and data assimilation.

This suite of mathematical algorithms, researched, designed and developed at Bath, is called Multi-Instrument Data Analysis System (MIDAS). MIDAS is the culmination of over 20 years of our space-based communication research and is used under licence by many other academic institutions across the globe.

Using MIDAS we are able to reconstruct highly-accurate three-dimensional images of the Earth's ionosphere. MIDAS works in real-time, so it can continuously monitor and determine the changing nature of the ionosphere as it responds to space weather. It then uses this information to calculate the exact effect of this weather on position errors in GPS measurements to improve their accuracy.

The threat from organised crime

As GPS technology has permeated so many different technologies and services, it has become a major target for criminals looking to cause disruption or avoid capture from security services. Aviation, shipping, banking transfers and communications are all vulnerable to illegal activities.

One recent high profile case saw a criminal gang use GPS jamming systems to hide their car theft and refit enterprise (known as 'chop shops'). Through our research in ionospheric scintillation measurements, we've been able to develop ways of detecting GPS jamming signals and even find the location of the jamming source. In this case, the UK police were able to recover 30 stolen cars and make 12 arrests.

Isolating and distinguishing GPS signals

Using a highly specialised GPS receiver and mathematical analysis we can identify abnormal signal behaviour. By comparing this against the normal behaviour we would expect, we were able to design and develop new algorithms to isolate signal anomalies and their causes (whether natural or criminal) in real-time.

Our GPS signal processing research has helped to develop sensors, known as Interference Detection and Monitoring sensors (IDM), and a series of algorithms for interpreting the data from these. These IDM devices identify the location of a GPS jammer and even its direction.

New technology to track down criminal gangs

Working with Chronos Technology Ltd, a UK-based SME, we've helped to develop their new detector product range and service. Chronos detectors provide real-time alarm signals so security services can find jamming perpetrators.

These devices have been sold to the civilian, defence and security markets in the UK, North America and Europe.

The latest Chronos product to emerge is known as “JammerCam” and is the first GPS jamming detector in the world to be able to take photographs of a moving vehicle which is carrying a GPS jammer.