Ghost Ships, Crop Circles & Soft Gold: A GPS Mystery In Shanghai

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Fortea Morgana :) PeteByrdie certificated Princess
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marhawkman

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GPS is actually easy to jam. it's a rather weak ground to satellite signal. Part of why it's reliable is that GPS is normally the only thing using that band. White noise broadcast at the right frequency won't require an exceptionally powerful transmitter. Which is kinda the trick to efficient signal jamming. focus the jammer so that you're not inundating every wavelength in a 1-mile radius. Focused takes far less power and might not even be noticed except by your target.

But the last part is the most interesting it suggests that the cause is people borrowing transponder codes, thus the spoofed location is because someone is using a fake copy of their code. Thus the idea is that criminals in Shanghai have figured out how to make GPS functionally useless.
 
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INT21

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marhawkman,

I think you are missing the main point.

That is, the signals gps was apparently showing a ship in the wrong place. Not just being blocked.
 

Lobeydosser

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Great name.... I patted the statue only a wee while back!
Thanks - had a varient (with a dash in the middle I think ) on the "old" board when it first started - but, lost the mail and password for it long ago.
Been lurking since the days of looking up Forteana and Ghost stories etc on newsgroups (remember those ?) while working night shifts doing intenet support (dial up) in a deserted building in Glasgow city centre - not good for the nerves :pop:
As it happens I also worked in the old Nautical college in Glasgow (now long merged into a new institution) and recall the fun and games when a student accidently triggered the emergency locator beacon on the roof of the building (it was there for training purposes) and briefly caused a potential air sea rescue effort to be launched looking for a college sinking in the middle of Glasgow.
All in all it's remarkably like the plot to the old Bond film "Tomorrow never dies"
 

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Fortea Morgana :) PeteByrdie certificated Princess
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and briefly caused a potential air sea rescue effort to be launched looking for a college sinking in the middle of Glasgow.
:rollingw:

yes, my night shifts lead to lasting interests :)
 

marhawkman

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marhawkman,

I think you are missing the main point.

That is, the signals gps was apparently showing a ship in the wrong place. Not just being blocked.
That article suggested part of the problem was pirates using fake GPS transponder codes. If a pirate is using a code that matches a real ship, the system would go bat-shit. GPS tracking software is written to assume that each transponder code is only in use by one transponder at a time. It's possible that if the real transponder and fake pinged at the same time the receiver wouldn't be able to process both pings and would drop them entirely. Thus causing a temporary loss of location data.

Why is easy. The local police check all water traffic for GPS transponders as part of attempting to guess which are pirates. It's basically a modern false-flag gimmick.

Which leaves the question of how the pirates are faking GPS transponder codes. Also it's possible they're not leaving the fake transponders on all the time.
 
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