Hi
The main point is: If you are looking at a VLF system, phase matters a lot. If
your
objective is a 100 ns @ 1 second sort of accuracy, you need a very stable phase.
At 100 KHz, you are looking at 3.6 degrees of phase shift. Go down to 60 KHz and
you are right at 2 degrees. Head to Omega sort
Hi
> On Aug 8, 2020, at 7:18 PM, Bill Byrom wrote:
>
> Yes, the weather can change the phase of the transmitted antenna signal
> unless corrections are performed. From the WWVB (60 kHz VLF time/frequency
> station at NIST in Fort Collins, CO) website at
>
Yes, the weather can change the phase of the transmitted antenna signal unless
corrections are performed. From the WWVB (60 kHz VLF time/frequency station at
NIST in Fort Collins, CO) website at
https://www.nist.gov/pml/time-and-frequency-division/radio-stations/wwvb (see
second paragraph
Hi
> On Aug 8, 2020, at 4:15 PM, Hal Murray wrote:
>
>
> kb...@n1k.org said:
>> Same basic issue, lots of weird interactions and a need to keep the signal
>> very precise. Not as easy as it might seem.
>
> What does "precise" mean in that context?
>
> I'm not an antenna-nut. Can an
kb...@n1k.org said:
> Same basic issue, lots of weird interactions and a need to keep the signal
> very precise. Not as easy as it might seem.
What does "precise" mean in that context?
I'm not an antenna-nut. Can an antenna miss-match change anything other than
the amplitude?
How do you
Hi
> On Aug 7, 2020, at 10:48 PM, Bill Byrom wrote:
>
> Whit Griffith N5SU was the Chief Radio Scientist (or some similar title) for
> Continental Electronics in the 1980's in Dallas. In around 1990 Whit gave a
> slide show presentation to a Dallas Amateur Radio Club meeting at the
>
Bill Byrom writes:
> Figure 6 shows differences between daytime and nighttime propagation of
> pulsed signals. The received signal is a combination of the ground wave
> signal and one or more skywave signals (which are delayed with respect to the
> ground wave signal).
This is a
Hiya,
Thank you for all the thoughtful replies on list and a couple received
off list too.
There is at least one VLF station in north western Australia which I
think will be close enough to at least warrant the experiments, so will
get myself set up with a loop antenna and suitable SDR and
Whit Griffith N5SU was the Chief Radio Scientist (or some similar title) for
Continental Electronics in the 1980's in Dallas. In around 1990 Whit gave a
slide show presentation to a Dallas Amateur Radio Club meeting at the National
Communications Museum, a project at the Dallas Communication
Hi
Back in the day, if you hung out for a while in the lobby at Continental
Electronics, you would notice a
model of an old style transmitter over by one wall. Go over and look a it for a
a while and all the usual
parts were there. Couple of big tubes, big matching coil insulators here and
On 8/7/20 4:13 PM, Bill Byrom wrote:
See this 1961 IRE paper at the NIST website:
https://tf.nist.gov/general/pdf/2303.pdf
IRE merged with AIEE in 1963 to form IEEE.
Figure 7 shows the calculated amplitude transfer of the ground wave signal vs
frequency and distance. Note that for 100 kHz
See this 1961 IRE paper at the NIST website:
https://tf.nist.gov/general/pdf/2303.pdf
IRE merged with AIEE in 1963 to form IEEE.
Figure 7 shows the calculated amplitude transfer of the ground wave signal vs
frequency and distance. Note that for 100 kHz signals, the ground wave signal
is
Exactly and at night you have groundwave and skywave. In reality both exist
all of the time its just the strength changes. This is why LORAN C radios
have ability to reduce the effects of skywave. It has to do with the
structure of teh transmitted signal.
Paul
On Fri, Aug 7, 2020 at 6:25 PM
Gilles Clement writes:
> Would’nt 100khz carrier propagate mostly by ground wave (during day time) ?
> So following earth curvature ?
First: It's not really a 100kHz carrier, it is a 85-115kHz spread-spectrum
signal.
Second: Yes, and that is exactly the point.
--
Poul-Henning Kamp
Would’nt 100khz carrier propagate mostly by ground wave (during day time) ? So
following earth curvature ?
Gilles.
> Le 7 août 2020 à 21:34, paul swed a écrit :
>
> Taka
> Yes it does. More ionosphere than air. It would be skywave or indirect
> path. I mentioned that earlier.
> Now silly
Taka
Yes it does. More ionosphere than air. It would be skywave or indirect
path. I mentioned that earlier.
Now silly thought would a huge antenna work especially if you are at the
antipode. Further would it be gray line propagation.
Thats just silly talk. But something to think about.
Regards
Hi
The idea is that over a limited coverage area, you can supply “correction” info
to reduce the impact
of propagation. GPS (and other GNSS systems) do this sort of thing already.
Just as with GNSS, the
corrections will (likely) only get you just so far.
Bob
> On Aug 7, 2020, at 11:32 AM,
Wouldn't such a long distance propagation result in less precision? The signal
will have to go through distance through air which isn't constant in dialectic
values. Wouldn't it be problematic for level of accuracy we pursue?
---
(Mr.) Taka Kamiya
KB4EMF /
I believe South Korea is indeed building new eLORAN chains. I have seen
mention of it.
With respect to distance In the US I could occasionally receive the
European West chain at night and in the winter. Thats about 3200 miles. It
would also be by skywave so that deteriorates accuracy.
Regards
Paul
Are not South Korea are building one? new eLoran chain? Are they transmitting?
But don’t underestimate the distances from south east Asia to the far side of
Australia.
/Björn
Sent from my iPhone
> On 7 Aug 2020, at 10:24, Poul-Henning Kamp wrote:
>
>
> Hugh Blemings writes:
>
Hugh Blemings writes:
> Been following this thread with the usual mixture of joy, awe and wonder
> (truly!) - fantastic stuff :)
>
> My read of the situation is that there is next to no chance of receiving
> any meaningful signal at the VLF frequencies in question down here in
>
Hi,
Been following this thread with the usual mixture of joy, awe and wonder
(truly!) - fantastic stuff :)
My read of the situation is that there is next to no chance of receiving
any meaningful signal at the VLF frequencies in question down here in
Melbourne - a great circle path of some
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