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

Bob kb8tq kb8tq at n1k.org
Fri Aug 7 01:09:26 UTC 2020 

Hi

> On Aug 6, 2020, at 7:28 PM, Forrest Christian (List Account) <lists at packetflux.com> wrote:
> 
> 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.

Right now GNSS systems run in somewhere between 3 and 5 “bands” depending
on how you count them. Various chunks of spectrum between 1 and 2 GHz get 
used by this or that system.

Bob



> 
> 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
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