On Friday, November 15, 2019 at 10:35:13 PM UTC-5, wrote:
On Fri, 15 Nov 2019 18:58:30 -0800 (PST), Its Me
wrote:

What it sounded like in the article is that the AIS systems in the ships were being spoofed to report false
locations. If the entire GPS system was being spoofed ALL the locations would be jumping around.

===

The AIS transponders get their positions from GPS. It's not necessary
to jam the entire GPS system, just over ride the locally received
positions with a stronger signal. That is fairly easy to do since GPS
receiver antennas are omni directional.

Understood, but in that case the ship that was seeing other ships move around would have been moving around itself, since it would be seeing the same spoofed GPS signals. It wasn't, only the othe ship was moving. That sounds like the AIS signal from the other ship was being spoofed, not the entire set of GPS signals from multiple satellites. And it would be much easier to spoof a single AIS signal from a ship than multiple GPS signals coming from multiple satellites.