According to a Chinese state-sanctioned study, signals from SpaceX Starlink broadband internet satellites could be used to track US stealth fighters, such as the F-22.

They can claim that all they want but the reality is: It's not that useful militarily, and if it were, Beijing almost certainly wouldn't let anyone blab about it.

The research details how the academics were able to recognize the rough location of a commercial drone by observing disturbances in electromagnetic signals from Starlink satellites caused by aircraft passing through them. The system could "provide significant advantages in detecting small and stealth targets," the team claimed.

The academics, led by professor Yi Jianxin from Wuhan University's School of Electronic Information, launched [paywall] a commercial DJI Phantom 4 Pro drone and sent it over the coast near the Chinese city of Guangdong. The researchers chose the drone as they estimated it has the same radar signature as a modern F-22 fighter.

They reported being able to detect up the drone - not by hammering it with easily identifiable radar pulses (which would invite a counterattack in a war situation) but by identifying where the drone reflected the signals from a Starlink satellite orbiting overhead. The test was overseen by the Chinese government's State Radio Monitoring Centre.

"By using third-party radiation sources, radar systems can have enhanced concealment and anti-jamming capabilities," Yi and his team wrote.

Before people panic, this isn't exactly new technology - other than in the use of Starlink satellites to spot a target. Passive radar systems like this have been in use since the Second World War with the German Klein Heidelberg system, and today some radio enthusiasts are expert at getting a return from passing objects just by monitoring signal disruption - or scatter, as it's known.

But the Chinese suggested that Starlink would give them much more potential scatter to spot, and that modern chips and software will make interpreting the signals easier.

"Low-orbit satellite signals have the advantages of [being] all-weather, cross-regional and low-cost, which can be perfectly combined with covert forward scatter radars," the team wrote.

The academics suggested they could build a Starlink antenna relatively cheaply and use this on a directional base to follow aircraft using custom-designed signal processing software and "an undisclosed high-performance chip." Quite how well that would work with an emission-absorbent stealth aircraft - as opposed to an off-the-shelf commercial drone - remains to be seen.

Even if the rough position of a high-speed F-22 might be deduced, you still have to get high-precision information on its rapidly changing location for a weapon to lock onto it. It's a similar conundrum to knowing there's a mosquito in the bedroom at night and actually being able to swat it.

Given the limitations of the exercise, Yi admitted that the "feasibility and effectiveness" of the system for military use was still in question but said it could form the basis of further research. Color us extremely skeptical.

It's convenient for China to put this info about - if only to spread a bit of mischief. ®

https://www.theregister.com//2024/09/17/china_starlink_stealth/