[time-nuts] eLORAN will be on the air GRI 99600

Thu Aug 6 23:28:33 UTC 2020

If you look at generally-available GNSS PNT solutions, you'll find a few
failure modes:

1) Loss of a satellite (or two).   This is why the constellations have more
satellites than is strictly necessary, so not a big deal.

2) Loss of control/failure in the control system/constellation wide
software failure, aka the recent Galileo failure.   This is why you have
multiple GNSS constellations.

3) Ground based interference (jamming, spoofing), etc.    This is why you
need a terrestrial backup, which doesn't really exist.

For timing, I wouldn't be opposed to someone flying (or adding a payload
to) a couple of geostationary satellites which live in a separate band from
GNSS.  It would be interesting to be able to put up a small satellite dish
and get a highly reliable and hard to interfere with timing alternative to
GNSS.    I know there are two way time transfer options out there, I'm more
thinking basically a fixed-location cesium clock in the sky.

But, a good quality terrestrial option would be useful too.

On Thu, Aug 6, 2020 at 3:40 PM Bob kb8tq <kb8tq at n1k.org> wrote:

> Hi
>
> > On Aug 6, 2020, at 4:40 PM, jimlux <jimlux at earthlink.net> wrote:
> >
> > On 8/6/20 9:17 AM, Taka Kamiya via time-nuts wrote:
> >> Someone in this thread mentioned "at least 2 satellite time and
> frequency solutions" exists already.  I only know of GPS (GNSS)
> constellations.  What's the other?
> >
> > Transit?
> >
> > I don't believe they are still operational, though.
> >
> >
> > I wonder if one might be able to pick up time/frequency from a
> commercial TV broadcast transponder.  The transponders on the satellite are
> typically bent pipes (for C-band anyway), I would assume that the uplinks
> may or may not have stability comparable to terrestrial broadcast.
> >
> > One problem is, of course, that the satellites aren't in a stable
> location (at least on a "meters" scale) - but one could certainly do
> "common view" kinds of time transfer.
>
> Another couple of “up in the air” question:
>
> Some of the systems transmit “stand alone” signals in each of two or three
> different bands. Does each
> band count as a separate time source?
>
> If you know your location already, each sat in these systems can be a time
> source all by it’s self. Do they
> each count?
>
> I guess is depends a lot on just how you look at redundancy ….
>
> Bob
>
>
> >
> >
> >
> >
> >> ---------------------------------------
> >> (Mr.) Taka Kamiya
> >> KB4EMF / ex JF2DKG
> >>       On Thursday, August 6, 2020, 12:01:27 PM EDT, paul swed <
> paulswedb at gmail.com> wrote:
> >>    Magnus
> >> Its honestly by luck that I know anything. From the bits I have read
> Europe
> >> seems far closer to eLORAN then we are. Perhaps 6 months ago the US
> >> performed a series of tests 2 eLoran solutions and something like 6 or
> more
> >> satellite solutions. I know the old Iridium satellites were in the tests
> >> and some other LEO satellites.
> >> But thats about it.
> >> What we need is a cheap SDR LORAN C sniffer. Low power runs 24 X 7 and
> >> turns a LED on if the stations active.
> >> Oh well another project in the someday pile.
> >> Regards
> >> Paul
> >> WB8TSL
> >> On Thu, Aug 6, 2020 at 2:42 AM Magnus Danielson <magnus at rubidium.se>
> wrote:
> >>> Hi Paul,
> >>>
> >>> I only ask as you seem to track this thing the best here on time-nuts,
> >>> as far as I have seen, such that it is your emails that keeps me best
> up
> >>> to date with the progress.
> >>>
> >>> Cheers,
> >>> Magnus
> >>>
> >>> On 2020-08-05 19:21, paul swed wrote:
> >>>> Hi Magnus been a while since have emailed.
> >>>> Its one site that was a test transmitter. Its in New Jersey, USA.
> >>>> The goal of the testing I believe is to establish the viability of an
> >>>> alternate PNT reference to GPS. Additionally the ability to
> communicate
> >>>> some level of message broadcast. This should be identical to
> proposals I
> >>>> have heard of in Europe.
> >>>> But I have no direct relationship to any of this. Like you, a very
> >>>> interested observer and hope that eLORAN wins the battle.
> >>>> Unfortunately there are many alternate proposals such as using other
> >>>> satellites. Hmmm if I wanted to advance my career in the Air Force or
> >>> Space
> >>>> Force (Yes thats actually real now).
> >>>> Would I select the lowly reliable as heck eLORAN at sub $100 M/year to
> >>>> operate. Or the glorious space based proposals in $B region. Never
> mind
> >>>> that at least 3 countries now have demonstrated killer satellites.
> >>>> Sorry for that editorial.
> >>>> Regards
> >>>> Paul
> >>>> WB8TSL
> >>>>
> >>>> On Wed, Aug 5, 2020 at 11:04 AM Magnus Danielson <magnus at rubidium.se>
> >>> wrote:
> >>>>
> >>>>> Hi,
> >>>>>
> >>>>> Do you know that they would do test with two actual transmitter
> sites?
> >>>>>
> >>>>> Cheers,
> >>>>> Magnus
> >>>>>
> >>>>> On 2020-08-05 16:00, paul swed wrote:
> >>>>>> Hello to fellow time nuts.
> >>>>>> Warm up those old Austrons. eLORAN out of New Jersey has been on the
> >>> air
> >>>>>> intermittently prior to a test run next week. Due to the storm they
> >>> have
> >>>>>> lost power and should have it back today or tomorrow.
> >>>>>> The intention will be on the air operation till the 20th. That's a
> long
> >>>>>> run. Nice.
> >>>>>> Seems the Austron 2100s can be had for reasonable money these days
> >>> also.
> >>>>>> Enjoy.
> >>>>>> Paul
> >>>>>> WB8TSL
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-- 
- Forrest