SpaceX Starlink satellite internet could berebuilt to work as a global positioning system (GPS), according to a new paper published by researchers at the University of Texas. To do this, scientists had to intercept signals from satellites.
In a study published in MIT TechnologyReview, the possibility of using Starlink satellite signals for position, navigation and time (PNT) is being considered. Initially, the researchers found that the antenna was internally protected, and considering that time is critical to GPS, but the clock on the Starlink dish proved to be unreliable. Therefore, for the experiment, it was decided to make their own signal receiver, for which a steerable parabolic antenna was used with publicly available data from SpaceX about the coordinates of the Starlink satellites. To ensure that signals were always available to “listen in”, the Starlink terminal continuously downloaded high-definition videos from YouTube.
The test showed that the Starlink signal is dividedinto eight channels, each with a bandwidth of 240 MHz. Of these, SpaceX is only using six channels, and the two channels at the bottom are empty - the authors suggest that this is due to the fact that they are close to the frequencies used by astronomers.
Using signal for positioninginvolves the analysis of its synchronization sequences. When transmitted from a satellite to an antenna, the signal uses the so-called orthogonal frequency division multiplexing OFDM. This allows the main signal to be split into several smaller signals, and the cymbal is responsible for merging or “synchronizing” them when received.
According to the researchers, a separate receiver likethe one they used can be used to predict timing sequences, which can then be used to reproduce a signal that matches the variables needed for GPS positioning. In addition, they also found that the reproduced signal has a strong correlation with the real Starlink signal.
This study also shows that interveningStarlink coverage is very simple, as attackers only need to create signals with a timing similar to Starlink signals in order to confuse user terminals.