[time-nuts] GPS Spoofing

[David]

John, Omega did make it into the 'uP age' I briefly got involved in the 
80's and my first patent was for using DSPs and software radio for an 
Omega development . The key thing was Omega was genuinely world wide 
from a small chain of transmitters and one of the important users had to 
do their navigation while staying underwater for weeks on end, even 
Loran had limitations never mind satellite.

It might be the answer "the mystery Collins Ru" posting here, I remember 
similar items in airborne Omega receivers, the omega carrier frequencies 
were low but the receiver bandwidths were measured in mHz and phase 
error was critical hence the boxes I saw included similar references.

Its rather painful to see all the warnings about GPS made 30 years ago 
having to be re addressed. I suspect Loran will not get a big revival, 
the important development since the '80s is probably cheap MEMS inertial 
measurement sensors that give a user a secure cheap independent 
accessory to integrate with GPS etc. Its not an alternative but a rather 
useful thing to merge into a system to help deal with spoofing or other 
signal loss, this page from Analog Devices shows prices and performance:

http://www.analog.com/en/mems-sensors/mems-inertial-measurement-units/products/index.html#iSensor_MEMS_Inertial_Measurement_Units

There are other opportunistic navigation systems that try (tried?) other 
approaches such as Peter Duffett-Smith's Cursor system which I think is 
now in the hands of CSR.

Regards
David


> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sun, 28 Jul 2013 15:24:30 -0700 (PDT)
> From: "J. Forster" <jfor at quikus.com>
>
> Subject: Re: [time-nuts] GPS Spoofing
>
> I'm not so convinced about this:
>
> "OMEGA was the primary means of radio navigation, world wide, from 1976 to
> 1997. ."
>
> There was LORAN-C, after all.
>
> And Omega was a CW, phase difference system, LORAN a pulse system.
>
> AFAIK, Omega never really made it into the uP age; LORAN certainly did.
>
> -John
>
> ===========
>