[time-nuts] GPS Spoofing

Bob Camp lists at rtty.us
Mon Jul 29 18:22:01 EDT 2013


Hi

Omega is a lane based system. You need to know your start point to keep track of where you are. That made small boat units impractical. Pre-GPS Loran was pretty much the only small boat option. Once cheap GPS came out, Loran sales in that market went to zero. 

Bob

On Jul 29, 2013, at 8:57 AM, J. Forster <jfor at quikus.com> wrote:

> Well, OK, but I never saw a small, <$500 box that could be put on pleasure
> boats, etc. and directly read out Lat/Long. Such things were available at
> the local boating store for LORAN.
> 
> -John
> 
> ==============.
> 
> 
> 
> 
>> 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
>>> 
>>> ===========
>>> 
>> 
>> 
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> 
> 
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