Weekly Takeaways-August 25, 2022
Theme of the Week
Global Timing System (GTS) A fundamental flaw of the half-century-old GPS is that it tries to do too much for too many. It was originally designed to provide position and time for the US military. But it was a victim of its own success and now most of the modern world relies on GPS. Because of this broad range of needs, a one-size-fits-all replacement is way too difficult. This is a problem for networks that rely on timing from GPS, which has an accuracy topped out at 30 nanoseconds. This accuracy enabled 4G LTE and is barely good enough for 5G (with expensive equipment). But 6G networks need sub-nanosecond accuracy. So do efficient data centers and quantum networks. A “better” GPS (whatever that means) won’t get there. What is needed is new technologies and architecture. What is needed is a dedicated Global Timing System (GTS). Last Week's Theme: Jack of All Trades, Master of None
In addition to a recent quantum satellite called Jinan 1, China also demonstrated a compact QKD terminal on their Space Lab Tiangong-2. These quantum payloads are more compact than the original quantum payload demonstrated on Micius in 2016 that was “about the size of a large refrigerator... weighed around 130 kg and required 130 W of power.” In contrast, the Tiangong-2 quantum payload “weighed around 60 kg, required 80 W of power and measured about the size of two microwave ovens,” while the Jinan 1 quantum satellite “weighs about a sixth the weight of the Micius satellite and contains a QKD system that is about a third of the size of that demonstrated [aboard Tiangong-2].” So approximately 20 kg for a quantum payload on a 100 kg satellite that was "designed to carry out real-time satellite-to-ground QKD experiments, representing another important step toward low-cost and practical quantum satellite constellations."
Chinese researchers also recently demonstrated quantum entanglement between two memory devices located 12.5 km apart, as a further step towards the development of a quantum network. According to the researchers: “In 2020, we published a paper in which we demonstrate the entanglement of two quantum memories via a fiber link of 50 km. In that experiment, both two memories we used were located within one lab and thus not fully independent. The next step in our research was to make the two memories fully independent, while placing a long distance between them.”
Another solar storm passed by the Earth last Wednesday, peaking at around a G3 on a scale to goes up to G5. A G3-level storm is considered “mostly manageable without risk of power outages.” But it could be worse: NASA reported that the last G5-level storm impacted "about 50% to 60% of their satellite fleet.”
New space companies have shown their value in the war in Ukraine, and are also forcing the US government to consider rules for unique space missions: “We believe the new space age needs new rules. Because here on the ground, the regulatory frameworks we rely on to shape space policy were largely built for another era.”
Because GPS jamming is so pervasive, the Department of Defense (DoD) is working on “commercial technologies that could help detect GPS jamming or other activities that disrupt satellite-based navigation.”
Meanwhile, the Army is working to augment their Electronic Warfare Planning and Management Tool (EWPMT) to plan for operations in a GPS-denied environment. And there are also private efforts to create a real-time map of the GPS outages.
ION GNSS+ 2022, September 19 - 23, Denver, CO
IEEE Quantum Week 2022, September 18 - 23, Broomfield, CO
Quantum Industry Day, October 4, Zurich, Switzerland
APSCC 2022, October 18 - 20, Seoul, Korea
Tough Tech Summit, October 27 - 28, Boston, MA
International Timing and Sync Forum, November 7 - 10, Dusseldorf, Germany
The More You Know...
GTS Part II When people think of GPS, they think of maps. But GPS is actually more valuable as a clock for the world. GPS was designed to provide both position and time, but this makes it expensive: you need multiple satellites in view to resolve both together. One idea to improve on GPS is to split off position and time into separate architectures. Position is the easier problem to solve; all you need is a terrestrial beacon or landmark. But time is hard. It is always shifting. Clocks are always falling out of sync. A reference clock is a long ways away. And distance makes the sync harder. And as networks require better timing to increase throughput and efficiency, the problem is getting worse. Syncing two clocks to within a few seconds is easy. Syncing to a nanosecond (one billionth of a second) or better is much harder.