[time-nuts] GPS Spoofing

[Bob Camp]

Hi

On Jul 31, 2013, at 6:47 AM, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:

> On 27/07/13 13:19, Brian Alsop wrote:
>> If you know your LORAN has a 1/4 mile accuracy then you stay 1/2 mile
>> away from bad things.
>> 
>> The trouble with GPS is that it is so good, people don't use common
>> sense and give obstacles a wide berth.
> 
> The published civilian precision of GPS isn't much better than LORAN-C, but it gives much better performance now for many reasons, including many birds in view and SA turn-off.
> 
> You do have hit the point, normally GPS works so darn good for most usage, that you perceive it to always be there, out of flaws. It's now with GPS receivers in phones that people start to learn that you can be in radio-shadow...
> 
> GPS is a good service when it is there, but when it isn't quite there or gone, you need to have a backup-plan, and know when to execute it.
> LORAN-C is a good back-up plan.

Except that in practice Loran-C was much less reliable than GPS. Up comes a flag that says "GPS & Loran don't agree". The vast majority of the time it'll be Loran that's wrong. Very quickly a normal person will default right back to the GPS.

Bob

> 
> Cheers,
> Magnus
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