Why the world needs better and more robust ways of measuring time

Critical infrastructure and systems such as GPS rely on time-keeping mechanisms that are far too easily subverted or prone to error

Time is the hidden and fragile basis of our digital civilisation. The more efficient, integrated and faster our systems become - for communications, energy, transport, financial services - the more dependent they are on ultra-precise timings. With any slip in synchronisation errors accumulate, resulting in disorder, damaging delays, unreliable records and a breakdown in trust. The modern world has the potential to buckle and crash. So accurate timing has become one of the most important pillars to the resilience of developed economies.

Governments are aware of the issue, but internationally we continue to live with fragile systems and an assumption among non-specialists that time, at least, is one constant factor we can rely on. They are wrong. Systems are fragile because all physical measurement machines, when it comes to such high levels of precision, are prone to error.

And because global data signals have the potential to be jammed and spoofed by criminals and political enemies. Access to atomic clocks can become dependent on stable political relations.

The system clock tick rate for a typical desktop PC is just a microscopic tuning fork a couple of millimetres long. No two are identical and each will be affected by temperature in different ways, each will age differently. Typical drift is up to two seconds per day. The Windows operating system refers to the Windows Time Service, based on a pool of Network Time Protocol servers, which, again, has been found to involve clock inaccuracies of more than a second.

It once looked as if the problem was under control. The work of astronomers, calculating time from the movement of the Earth, was replaced by International Atomic Time (TAI): ultra-precise observations of the caesium-133 atom, and 340 atomic time clocks in different locations internationally. The most relevant of the atomic clocks to our everyday lives are contained within Global Positioning Satellites, the ubiquitous GPS. A free ‘global public service', GPS is made available by the US Government and operated by the US Air Force. This means information determining time to within 100 billionth of a second is shared globally wherever a signal can be received via satellites - making it unnecessary for individual organisations to operate their own atomic clock.

But GPS is a weak signal. It's cheap and easy to disrupt by transmitting noise on the same radio frequency. The UK government estimates that financial trading in London is affected by between 80 and 120 GPS jamming incidents every month. GPS satellites themselves can malfunction and solar flares interfere with signals. Meanwhile, GPS is relied on everywhere across all of our public and commercial infrastructures. Mobile phones and other wireless comms depend on rigid time standards (an accuracy level of less than one second difference over 3,000 years) to put signals into order, prevent congestion and ensure calls and messages from different operators can be synchronised. The same applies to electricity power grids that have to link up energy sources on the same frequency. In 2016, the de-commissioning of a single GPS satellite led to 12 hours of IT and phone system errors globally.

Accurate time stamps are critical for operations to be put into an order, to identify and avoid data bottlenecks, and to be relied on as evidence. For example, the dependence on the Internet and distributed computing means clocks are needed to put vast streams into sequence, as a conversation and not just giant lumps of noise. Financial institutions and other businesses need to have a guarantee of the time and date of transactions to the microsecond and the order they took place: an explicit chain of cause and effect that establishes responsibility. Attempts to unpick the causes of the trillion-dollar ‘flash crash' in the Dow Jones index in May 2010 were severely undermined by clocks that disagreed. Records showed transactions occurring before they had technically been sent. As a consequence, the EU introduced the MiFID II Compliance directive, demanding that banks synchronise clocks to within a hundred microseconds (millionths of a second). When another crash happened in the US in 2014, Treasury investigators studied events though a ‘slow-motion replay' at a millisecond by millisecond level.

The increasing and intensifying level of demand for accurate timings has exposed the essential need for multiple solutions for when things go wrong, a fail-safe back-up system to correct any misalignments. Cranfield researchers are working on technologies for trusted and reliable navigation, communication and surveillance, as well as timings for traffic management in digital aviation and transport in smart cities. The work is building on existing tech created by UK enterprise Hoptroff and its experience in the financial services sector developing a cloud-based back-up. The Hoptroff system is founded on a network of mutually resilient cloud timing hubs, each consisting of three nano-second accurate Grandmaster clocks connected to three different sources. The hubs continuously compare the different timing sources to ensure accuracy and source traceability are constantly maintained. To mitigate against satellite communication issues, the back-up is supported by a terrestrial location at Research Institutes of Sweden (RISE).

The accuracy of GPS is not being monitored to the extent needed for resilience - and that's dangerous. We need to take on the challenge of how national and linked international infrastructures can always depend on time data, and that means recognising the problem and investing in new ideas. At government level, in particular, that means breaking out of its shell of relationships and funding processes made for big commercial providers and be alert to the sharp emerging innovation coming through small and micro-enterprises.

Dr Simon Harwood is Director of Defence and Security and Dr Ivan Petrunin is Lecturer at Cranfield University; Dr Richard Hoptroff is co-owner of Hoptroff.