Position, Navigation & Timing: the technology the modern world runs on

What is PNT and why does it matter?

The best known PNT system is GPS (Global Positioning System), which powers the maps and navigation on your phone, all the way up to aircraft and beyond.

While GPS (an American system) was the first, several other global satellite systems now exist, including Galileo (European), BeiDou (Chinese) and GLONASS (Russian). These systems are collectively referred to as Global Navigation Satellite Systems (GNSS).

They all work on the same principle. Satellites orbiting the Earth broadcast faint signals and a receiver on the ground uses them to work out three things:

• Position – where you are
• Navigation – how to get from there to where you're going
• Timing – the precise time, accurate to within billionths of a second

Timing by itself is easy to overlook, but it may be the most important. Banks and stock exchanges use GNSS timing to order and stamp transactions, so that billions of payments a day happen in the right sequence. Power grids, mobile networks and data centres rely on the same precise clock. When people picture GPS failing, they think of a wrong turn on a satnav. The far bigger risk is everything else that depends on knowing the exact time. 

The risks of GNSS dependence

GPS became the world's default PNT system because it's accurate, reliable, free to use and available almost everywhere. Billions of people and devices now depend on it. One UK Government study estimated that a single day without GPS would cost the country around £1.4 billion.

That dependence is also a vulnerability. GNSS satellites sit roughly 12,000 miles above the Earth, so by the time their signals reach the ground they are extraordinarily weak, therefore easy to drown out and easy to imitate. There are three main ways to attack them:

• Jamming – overpowering the satellite signals with stronger interference to jam GNSS
• Spoofing – broadcasting convincing fake signals to feed a receiver the wrong position or time
• Physical attacks – targeting satellites to destroy or deny access entirely 

The equipment needed to jam or spoof is now cheap and easy to get hold of, making this a credible threat for any future global conflicts. Loss of PNT could disrupt military operations, send missiles off course, bring cities to a standstill, or cripple critical national infrastructure and financial systems that rely on accurate timekeeping. This is now a question of national resilience, not just military advantage.

Next-generation GNSS technology

This is the problem that QinetiQ built the Q40 to solve: a next-generation GNSS receiver for any situation where getting position or time wrong isn't an option; from defence and critical national infrastructure to industrial and commercial systems.

Rather than trusting every signal it receives, the Q40 combines purpose-built antennas and electronics with advanced signal processing to lock onto genuine satellite signals and reject the fakes. In practice, that means:

• It works through high power jamming, especially when paired with an anti-jam antenna
• It performs in contested areas and where GNSS signals are weak or degraded
• It draws on several satellite systems at once and fixes its position quickly from a cold start
• It delivers timing accurate to ~5 nanoseconds
• It's built in the UK on a sovereign supply chain and qualified to military standards

QinetiQ has produced two versions of the Q40, the Q40 MicroPNT for dismounted use, vehicles and UAVs, as well as the Q40 MicroStike, which is for use in precision guided munitions and test and evaluation of complex weapons, capable of withstanding extreme velocity, acceleration and vibration.

Terrestrial alternatives: eLoran

In addition to satellite-based solutions, QinetiQ is contributing to the development of eLoran (enhanced Long-Range Navigation), a land-based PNT solution that doesn’t rely on space. 

eLoran uses ground-based, low-frequency antennas to deliver PNT signals. These are significantly more difficult for adversaries to jam or manipulate, providing an alternative and backup option to GNSS that can operate in situations where satellite-based PNT is unavailable or denied.

QinetiQ is working closely with leading UK and international specialists to deliver this critical national capability. 

The future of PNT technology

For now, GNSS is certain to remain the main source of PNT. However, technology is always moving forwards and new systems are being developed to help overcome these potential shortcomings of GPS.

In parts two and three of this series, we’ll look at how quantum technologies, multi -sensor integration and data fusion are helping to create more resilient and reliable PNT solutions for the future.