[time-nuts] GPS Spoofing

[David McGaw]

LORAN can be good to 60 ft.


On 7/27/13 12:21 AM, Jim Lux wrote:
> On 7/26/13 8:45 PM, J. Forster wrote:
>> I gather from the article, the GPS position was spoofed and the 
>> autopilot,
>> in bringing it back to where it was supposed to be, actually took it off
>> course.
>>
>> There are places where a few hundred feet makes a big difference, 
>> viz. the
>> Costa Concordia.
>>
>> IMO, this is a very convincing reason for something like LORAN.
>
> I think it's a convincing argument for a captain who pays attention to 
> the other navigation instruments and doesn't blindly follow the GPS.
>
> It's also a convincing argument that shipboard 
> automation/autopilot/autocontrol vendors need to make more 
> sophisticated software (which I suspect they do, particularly on 200+ 
> foot ships.. I would imagine that there are some aspects of this demo 
> that are contrived.)  The ship making and driving business is pretty 
> unregulated. It's all about what the owner of the ship is willing to 
> pay (or what he needs to get liability insurance, if he wants).  
> There's nothing even remotely like DO-178 for shipboard stuff.
>
> The folks doing stabilized oil rigs probably have sophisticated 
> systems, but they're also using IMUs and other stuff. Ditto for high 
> value things (oil tankers, warships).  Molasses tankers? They're 
> probably lucky to have a functioning compass and some old charts.
>
>
> I'm not sure, though, that looking at the big picture, whether your 
> tax dollars are better spent on LORAN, or on some other precision 
> navigation method or on making jam resistant GPS receivers (which do, 
> in fact exist, and make use of things like direction of arrival of the 
> signal..)
>
> Note that a GPS system with 3 antennas (as is common in systems that 
> use GPS to derive attitude/orientation) would be extremely difficult 
> to spoof, and would be VERY inexpensive to implement. Either the 
> carrier phases and code phases are consistent for all the received 
> signals or they're not.  A jamming signal coming from the wrong 
> direction will not have the right direction of arrival relative to the 
> platform orientation.  One wrong signal might be tolerable (multipath, 
> etc.) but with a multi satellite fix, I suspect it would be hard to do 
> it.
>
> Sure, one could throw up N pseudolites on a bunch of UAVs, etc., but 
> that's getting to be a bit noticeable.
>
>
> For what it's worth, I don't know that LORAN has the performance to 
> avoid a Costa Concordia type foul up (assuming they were crazy enough 
> to do the near pass in the fog, so visual navigation didn't work)
>
> I seem to recall that LORAN had 1/4 nmi kinds of accuracy.  it would 
> get you to the channel or mouth of the harbor, but not get you into 
> your berth. You might be familiar with the local propagation anomalies 
> and get better accuracy with experience in your local waters.
>
>
>
>
>
>
>>
>> -John
>>
>> =================
>>
>>
>>
>>> I boat?  The backup is a competent captain.  He'd see the compass 
>>> heading
>>> move and quickly disengage the autopilot.   I had a boat for years  I'd
>>> notice a 5 degree change.  Mine was a sailboat so I'd be more 
>>> sensitive to
>>> heading changes than a power boater but still the human is the backup.
>>>
>>> Most autopilots don't directly follow GPS, they use GPS to determine a
>>> heading, follow it then use GPS to detect drift and re-compute the
>>> heading.
>>>   the heading would be held by a compass sensor in a low-cost setup 
>>> or in a
>>> larger setup a lazer ring gyro backed up by a compass.     So a spoofed
>>> GPS
>>> would cause the autopilot to "think" there was a bigger crooswnd or
>>> current
>>> and make a bigger heading change.
>>>
>>> I bet you could hijack a drone not a manned vehicle the pilot is 
>>> trained
>>> to
>>> monitor the automation and he'd very quickly turn it off thinking it 
>>> was
>>> broken.
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Fri, Jul 26, 2013 at 8:41 AM, J. Forster <jfor at quikus.com> wrote:
>>>
>>>> Prof. Humphry from Texas just reported being able to spoof GPS in the
>>>> Med
>>>> and take over the nav system of a luxury yacht. He's done this before
>>>> with
>>>> a drone in the US.
>>>>
>>>> LORAN as a backup, at least?
>>>>
>>>> -John
>>>>
>>>> ==============
>>>>
>>>>
>>>>
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>>>
>>>
>>>
>>> -- 
>>>
>>> Chris Albertson
>>> Redondo Beach, California
>>>
>>
>>
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>
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