[time-nuts] Can eloran Backup GPS?

Bob kb8tq kb8tq at n1k.org
Sun Sep 9 13:05:50 EDT 2018


Hi

Back in the day, Loran was monitored and corrections were published. If you
really were “time nutty” about using Loran, you got the correction tables (in the
mail)  and post processed them into your measurements. 

Bob

> On Sep 9, 2018, at 11:34 AM, paul swed <paulswedb at gmail.com> wrote:
> 
> The correction stream is transmitted in the eLORAN signal and does require
> some form of reference site to transmitter connection. Just like GPS and
> lightspeed use RF to send corrections to the satellites.
> Loran C also did the same adjustments from a control site.
> But I am hearing nothing about eLORAN these days. It does not show up very
> often anymore in some of the navigation publications.
> Regards
> Paul
> WB8TSL
> 
> On Sun, Sep 9, 2018 at 11:20 AM, Poul-Henning Kamp <phk at phk.freebsd.dk>
> wrote:
> 
>> --------
>> In message <3d2ae1be-927a-574a-e7f0-c7d2d289dc39 at earthlink.net>, jimlux
>> writes:
>>> On 9/8/18 4:52 PM, paul swed wrote:
>> 
>>> I suppose you could have a low rate network (i.e. not "the internet")
>>> and for the most part, the propagation corrections (whether using 60kHz,
>>> Loran, Omega, or GPS) can be done with "climatology" - time of day and
>>> time of year.
>> 
>> Transmitting real-time corrections is not the problem, coming up
>> with them in the first place is.
>> 
>> One of the reasons eLoran failed to go anywhere in europe is that
>> tests showed that modern container freighters are big enough to
>> 'relevantly disturb Loran-C'.
>> 
>> Nobody has a clue how you could possibly measure the necessary
>> real-time corrections for narrow and heavily trafficked straits
>> like as The English Channel, The Great Belt etc.
>> 
>> For big/expensive boats, INS/IMU is the goto-solution, at around
>> $20-50k a piece, depending on specs.
>> 
>> In difference from anything relying on radio signals from people
>> you can maybe trust some of the time, INS/IMU is entirely on-board,
>> which can lower your insurance premiums if you sail certain parts
>> of the world.
>> 
>> --
>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>> FreeBSD committer       | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by incompetence.
>> 
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