[time-nuts] GPS Spoofing

J. Forster jfor at quikus.com
Sat Jul 27 13:40:03 EDT 2013


When Cape Cod LORAN was functional, I could easily see the pulses with a
few turn coil maybe a foot in diameter, roughly resonated, and a scope.

-John

======



> Key
>
> Problem with GPS is its easy to spoof on one level and have a complete
> denial of service on the other.   Out in California a while back a
> malfunctioning TV distribution amplifier jammed a major harbor and
> surrounding almost 25 sq miles affected all because of a 49.95 TV amp had
> a problem.  The military receivers had the same problem
>
> LORAN is virtually jam proof unless you have a very powerful transmitter
>
> Sent from my iPhone
>
> On Jul 27, 2013, at 11:17 AM, Michael Perrett <mkperrett at gmail.com> wrote:
>
>> I have seen a lot of differing opinions on GPS Spoofing and using back
>> up
>> systems on this thread. Most pretty good, but a couple off the mark a
>> bit.
>>
>> Here are a couple of comments on GPS Spoofing.
>>
>>   - There are anti-spoofing GPS receivers available - to "authorized"
>>   users. Typically DOD. Most, if not all, military receivers utilize the
>>   encrypted "P-Code", while civilians must use the more vulnerable clear
>> text
>>   "C/A code". The P-Code signals are very difficult to spoof unless you
>> have
>>   a-pirori knowledge. The newer satellites (GPS III) will have an even
>> more
>>   robust AS methodology.
>>      - Note: beware of P-Code, or Military, receivers available on eBay.
>>      They are useless without the encryption keys distributed by the US
>>      Government.
>>      - In the (near?) future there will be four civilian GPS Signals:
>> "The
>>   government is in the process of fielding three new signals designed
>> for
>>   civilian use: L2C, L5, and L1C. The legacy civil signal, called L1 C/A
>> or
>>   C/A at L1, will continue broadcasting in the future, for a total of
>> four
>>   civil GPS signals. Users must upgrade their equipment to benefit from
>> the
>>   new signals". ref
>>   http://www.gps.gov/systems/gps/modernization/civilsignals/
>>   - Receivers utilizing the new civilian GPS frequencies can solve the
>> GPS
>>   equations from more than one frequency and see if any one signal is
>> being
>>   spoofed. The new civilian frequencies will be more spoof resistant.
>>
>> Comments on using inertial measurement units (IMUs) to back up GPS.
>>
>>   - Current IMUs with even a "good" drift rate of say, 1 degree per
>> hour,
>>   available for around a few thousand dollars, will be off 60 nautical
>> miles
>>   after an hour of uncorrected operation. That can be reduced by other
>> sensor
>>   inputs (GPS, LORAN, pit-log or what ever you have), but the navigation
>>   solution will eventually degrade to the accuracy of the external
>> sensor. If
>>   my memory serves me for a really deep pocket navigator (having tens to
>>   hundreds of thousands of dollars, and a large amount of available
>> mounting
>>   space) IMUs with drift rates of up to a thousand times less can be
>>   purchased (that's ,001 miles per hour, or around a couple of meters
>> per
>>   hour), think submarines, etc.
>>
>> Using a dual sensor navigation system (or timing system! ), such as
>> GPS/eLORAN, would obviously make the system so much more robust.
>>
>> Michael / K7HIL
>>
>> On Sat, Jul 27, 2013 at 6:43 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
>>>>>>>
>>>>>>> ==============
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> time-nuts mailing list -- time-nuts at febo.com
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>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>>
>>>>>> Chris Albertson
>>>>>> Redondo Beach, California
>>>>>
>>>>>
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