[hpsdr] Fwd: 1, 2, 3, 4, 5, 6, 7....

[John Ackermann N8UR]

I don't know if that's true (you may be thinking of the old Selective 
Availability, which was turned off quite a while ago).  As I understand 
it, the main issue is that the geometry of the satellites just doesn't 
allow as precise a fix of altitude as it does the other axes.

To get best accuracy in altitude, you'd like a fix that includes 
reference points both above and below your location.  But the GPS can't 
see satellites that are below the horizon, so the quality of the fix 
suffers.

John

On 7/26/2012 11:15 AM, Tim O'Rourke wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
>
> US goverment keeps some of GPS altidude capability vauge for security
> purposes.
>
>
>     -----Original Message-----
>     From: Alberto I2PHD
>     Sent: Jul 26, 2012 10:58 AM
>     To: HPSDR list
>     Subject: Re: [hpsdr] Fwd: 1, 2, 3, 4, 5, 6, 7....
>
>     On 7/26/2012 1:42 PM, Simon HB9DRV wrote:
>>
>>     I have a Thunderbolt on my balcony; using Lady heather I can
>>     confirm that my house hasn’t moved by more than a few cms in the
>>     last year J
>>
>     Have you checked the altitude too ? My Thunderbolt tells me that
>     from the morning to the evening of the same day
>     my house moved up and down by almost 30 meters.... :-)   and the
>     antenna is firmly attached to one of the chimneys....
>
>     I guess that is one of the reasons why GPS is not used on any
>     aircraft, at least as an altitude measuring device...
>
>     --
>     /*73 Alberto I2PHD*/
>
>
> Tim O'Rourke
> W4YN at ARRL.Net
> Low Power Amateur Radio Rocks
> Member of Flying Pigs,ARCI,GQRP,RSGB,ARRL Life Member
> NHRA Life Member
>
>
>
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