On 02/06/2017 09:06 PM, Bob Camp wrote:
On Feb 6, 2017, at 7:38 PM, Ruslan Nabioullin
<[email protected]> wrote:
So any ideas on how likely it will be that eLORAN becomes deployed
with at least partial US coverage within the next 5--10 years?
No, this is not the world as I would like it to be. It is the world
we live in now and are likely to live in for the foreseeable future.
Yes, from the perspective of myself and my fellow transhumanists, the
world is quite primitive in all aspects. I yearn for the day when
singularity will take over and our primitive species is relegated to
wildlife status. But I digress, as usual.
If we are looking at it purely as a timing reference the outlook is
not real good. Best guess about 1 in 1,000. I’m probably estimating
that on the generous side. If there is some other magic use for the
thing (or a couple dozen other uses) that might change the equation.
Right now those other uses are not very obvious.
Why the lousy outlook:
1) The way a system like this gets funded is for it to have a lot of
users. It might also get funded if some crazy black project needs it.
That’s not happening with Loran. Loran died in the first place due to
a lack of users. 2) For a system like this to have a lot of users,
you need to pass regulations requiring it’s use. That may seem odd,
but that’s the way it works. Loran co-existed with GPS for a long
time. GPS was *less* reliable back then than it is today. Using
Loran for timing was a very rare thing outside a handful of labs. 3)
To regulate it into major systems, it needs to have at least a
country wide coverage and more likely a bit more than that. Without
that there isn’t enough of a timing market to address. You need to
retrofit it into every cell tower in the country (for instance). 4)
Loran getting into buildings from a single site (even fairly close) …
not so much if they are full of switching power supplies, you have a
problem. You need to have *many* Loran transmitters. Cell timing is
moving out of the “edge” and into the central hubs. That means
buildings full of switchers. 5) Tying multiple time sources into a
system costs big money. If you only have two clocks, how do you
decide which one is wrong? Not an easy question to answer. That money
has to come from somebody. Nobody wants to pay. The cell carriers
have never been excited about investment that does not immediately
result in more customers. 6) There are multiple competing “for pay”
backup timing systems. Adding another one to the mix is pretty hard
to justify. Even more so if you can “steal” timing off of one and not
pay for it. That would be the case with an eLoran that works with all
our old gear. 7) Like it or not, justified or not, cost effective
(not), the world is hung up on space based systems. There is no
excitement in 1950’s technology. 8) Loran for exact timing has some
major issues with propagation delay. If your goal is the same as the
system specs ( < 100 ns) that’s going to be a really tough nut to
crack. Do they *need* < 100 ns? It’s in the spec …
Makes sense---I was doubtful that it would be successful in non-niche
commercial areas, considering the different priorities and philosophy
(or lack thereof) in mind by the manufacturers and userbase.
Right now we have multiple broadcast time sources running 24/7 at
various frequencies with various coverage zones. As far as I know
*none* of them are tied into major systems. That’s just the way it
is, and it’s nothing new. Even in military systems, multiple time
sources into a system is a very rare thing. In commercial systems …
Yes, WWV/WWVH, WWVB, and CHU, within North America. Very sad to hear
that---fusing standards and external sources of diverse characteristics
(MTBF, Allan deviation, propagation mode, sociopolitical considerations,
etc.) is the central approach of my project.
WWVB altered the signal format in '12, rendering phase locked-loop-based
receivers into metal paperweights (i.e., the remaining lab units used as
a fallback), and apparently there is no replacement nor retrofit, like a
Costas Loop (the only receiver I have found is a Meinberg USB unit,
which very well might not even work with the new format; I have in fact
submitted multiple quote requests, to no avail). At the very least
millions of domestic and personal radio clocks use it (along with a
couple other analogs in some other parts of the world, like DCF77), not
that this approach is remotely optimal.
As for WWV/WWVH and CHU, it's quite a sad situation---I have only
counted 1--2 registered NTP servers that actually use at least one
channel, despite the fact that: 1. NTP has decoding modules built-in for
all these signals; 2. the equipment setup is typically simpler and
cheaper compared to dealing with mounting a GPS antenna on the roof and
interfacing with PPS, esp. if one uses a Chinese $6.50 incl. shipping HF
receiver off eBay; 3. it's a decent, and essentially only (not counting
CDMA---don't get me started on that!), external reference fallback to
GNSS. I actually had this crazy idea of starting a Kickstarter campaign
to educate the masses about time transfer resiliency, and to launch a
contest that would supply good public NTP server operators with free HF
receivers. These stations could very easily suffer the same fate as
LORAN-C under the Obama administration, unless a vocal userbase is built up.
-Ruslan
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