[time-nuts] GPS Spoofing

Bob Camp lists at rtty.us
Sat Jul 27 12:14:38 EDT 2013


Hi

Which is why the regulations (air or sea) *require*  you to be using at least two nav systems to check each other. If you are depending on only one system, your breaking the rules. It's not a matter of weather there are 100,000 systems available or not. It's a matter of weather they follow the rules. 

Bob

On Jul 27, 2013, at 9:43 AM, Scott McGrath <scmcgrath at gmail.com> wrote:

> Key here is how does the captain know that GPS is no longer providing an accurate fix?   You need 2 or more independent systems to cross check each other.  
> 
> Sent from my iPhone
> 
> On Jul 27, 2013, at 12:21 AM, Jim Lux <jimlux at earthlink.net> 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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