Dutch wrote:
> News wrote:
>
>
>>Dennis Ferguson wrote:
>>
>>>On 2008-04-07, clifto <clifto@gmail.com> wrote:
>>>
>>>
>>>>Richard B. Gilbert wrote:
>>>>
>>>>
>>>>>clifto wrote:
>>>>>
>>>>>
>>>>>>News wrote:
>>>>>>
>>>>>>
>>>>>>>clifto wrote:
>>>>>>>
>>>>>>>
>>>>>>>>Kurt wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>>"Richard B. Gilbert" <rgilbert88@comcast.net> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>>GPS, or at least the civilian version of it, is only accurate to within
>>>>>>>>>>about 300 feet or 100 meters.
>>>>>>>>>
>>>>>>>>>It's been changed for a few years, now more like 15 meters. Clinton was
>>>>>>>>>the one that changed that.
>>>>>>>>
>>>>>>>>http://www.navcen.uscg.gov/faq/gpsfaq.htm#Standard
>>>>>>>>
>>>>>>>>SPS provides accuracy's of (for position, the accuracy with respect to
>>>>>>>>geographic, or geodetic coordinates of the Earth) within:
>>>>>>>>100 meters (2 drms) horizontal 156 meters (2 Sigma) vertical 300 meters
>>>>>>>>(99.99% prob.) horizontal 340 nanoseconds time (95% prob.)
>>>>>>>
>>>>>>>"What is the status of Selective Availability (SA)?
>>>>>>
>>>>>>What does SA have to do with the 2008 accuracy specification I posted?
>>>>>
>>>>>IIRC, SA encrypted the low order bits in order to prevent GPS being used
>>>>>for weapons targeting and other anti-social behavior.
>>>>
>>>>That's true, but Clinton shut it off in 2001 and it hasn't been a problem
>>>>for nearly seven years now.
>>>
>>>Sure, but no one in the government said they wouldn't turn it back on if
>>>they felt like it which is why their SPS accuracy claims still always
>>>include the effects of SA.
>>>
>>>In fact the paragraph just above the accuracy specifications you quoted
>>>says, in part,
>>>
>>> "The SPS accuracy specifications, given below, include the effects of SA."
>>>
>>>which, I guess, is what SA has to do with the 2008 accuracy specification
>>>you posted.
>>>
>>>Dennis Ferguson
>>
>>Bingo.
>
>
> Except that the specs they show are with the old SA settings, not the
> current zero setting.
>


Correct, which voids the OP's accuracy and error probabilities.