By Dr. Tanya Ramond
The first GPS satellite was launched in 1978. The full constellation of satellites was realized by 1993, consisting of 24 satellites plus 7 spares. The GPS system was first conceived as a military device built by the Department of Defense, intended primarily for military use.
The basic idea is that each GPS satellite sends out by radio a precise time signal plus metadata about its position and orientation. The receiver receives signal from up to four satellites, and records the time of flight to arrive at the receiver. The time of flight from four different satellites allows calculation of the position of the receiver. So GPS sends a time signal, and the position is calculated on the ground, by the receiver.
When you think of GPS, your first thought is probably the map app on your phone that directs your driving from point A to point B. But in reality, GPS timing is an important infrastructure layer to our world. The US Department of Homeland Security has deemed GPS to be part of all 16 infrastructure sectors deemed ‘critical’, including telecommunications, financial industry, electrical grid, commerce, military, transportation and agriculture. And the economic impact of GPS is mind-blowing. In 2019 the National Institute of Standards and Technology published a study that concluded that GPS contributed a whopping $1B USD per day to the economy.
Despite the fundamental importance of this utility, GPS is actually a highly vulnerable target. We know that the Russians are working on kamikaze satellites that could take out a GPS satellite, and the Chinese are developing kidnapper satellites that can extend an arm to harm another satellite. That plus the fact that over 10,000 GPS interference events have been recorded in the last five years attributed to China and Russia alone, has the attention of National Security officials.
But sophisticated satellites are not required if one wants to take out GPS. The reason is that because the satellites are 20,000 km above the earth, once the signals make it to the earth’s surface, they are quite weak. That makes it easy to jam them (flood out the weak GPS signal with a stronger one at the same frequency) or spoof them (fake a GPS signal).
These interference events happen day in and day out because it is so easy to do. As an example, in 2019 a delivery driver unintentionally disrupted satellite tracking at Newark airport because of a GPS jammer he kept in his car to hide his location from his employer. GPS jamming is illegal, but the equipment is easy to obtain and inexpensive.
In 2016, a Cathay Pacific flight landing at Manila airport lost its GPS 8 miles from the runway. The pilots were told to land the plane by sight, and they were thankfully able to do so safely because weather was cooperative. This was not a rare occurrence, as that same airport recorded over 50 GPS interference events over 2 months that same year.
The bottom line is that it would not take much in terms of planning, coordination, and budget to orchestra a large-scale collapse across the country of electrical grids, aviation landing systems, cell phone towers, and stock markets. But the even scarier fact is that although countries like China, Russia, and Iran have terrestrial-based backup systems in place, the US does not, which makes it all the more vulnerable.
Despite this magnitude of weakness in the US infrastructure, the US government has a long history of inaction to address it. The first federal policy mandating a backup to GPS was issued in 2004. Since then there have been 9 different reports issued concerned with GPS backup. In 2018, the National Timing Resilience and Security Act was signed into law, requiring that the US erect a GPS backup system in two years. But the effort was not funded at the time and the backup system still does not exist. In February 2020, an Executive Order was published that essentially placed the onus for alternative PNT (position, navigation, and timing) on the shoulders of the private citizen and private industry, hoping to spur market adoption of APNT solutions (alternative PNT). And later in 2020, the Department of Homeland Security issued a report concluding that given the diversity of use cases for GPS in the economy, there will be no one single technology that will replace them all, and instead a portfolio approach is needed.
The private sector is starting to step in. In January 2021 the Department of Transportation released a report of performance of several APNT technologies against standardized representative scenarios for a PNT service. One company passed all the criteria, and the rest exhibited piecemeal performance. And late 2020 an APNT industry association was founded around growing the portfolio of market-based APNT solutions.
This is where Xairos comes in. Xairos offers satellite-based timing services exploiting a fundamentally different approach from the radio-based technologies currently available. Xairos uses a quantum-based approach that exploits the micro-properties of light that results in 1000x better accuracy of time transfer, on top of freedom from spoofing and hacking that is commonplace now. Stay tuned for more details in a future post.