[Lf] [Fwd: LF: Propagation misc.]

[Andre' Kesteloot]

Mitch Powell wrote:

> Hello Alan:
> I am forwarding a few items that may interest you
> and may conceivably  fill in some gaps, and even help.
>
> Following is a small piece from an article in the LOWDOWN
> by Brice Anderson, W9PNE, well known Top-Bander and
> LOWfer. This study was made several years ago with the
> participation of several active Lowfer beacon operators.
>
> "Quote"
>  Conclusions:
> 1   No long skip was heard when the A-index was below 3.
> 2   Long-skip was observed 50 to 100% of the time that the
>      A-index was 11 or higher.
> 3   An A-index of 15 produced the most nights of long-skip.
> 4   A-index numbers of from 7 to 24 produced the highest
>     quality openings. When the A-index was 25 or higher,
> there
>     were openings, but signals were weaker.
> 5   There were equal numbers of openings in Dec. Jan. Feb
>     and Mar, but the highest quality openings occurred in
> Dec.
>     and Mar. Feb was adversely affected by many
> thunderstorms
>     in the Midwest.
> "Endquote"
>
> In addition: An interesting letter in Technical
> Correspondence
> QST June 1994, page 78, by Robert Fischer, K2ND.
> He found a "remarkable" correlation between the Omega system
> (10-14 kHz) and loran systems (100 kHz) - and the
> propagation
> in the lower HF and VHF range.
>
> Unfortunately, as you know, the Omega system was
> 'terminated'
> on September 30, 1997 - and I do not know if there are other
> VLF sources that might serve the same function, as
> described.
>
> If you wish the article, I can certainly send directly to
> you as an
> attachment......  here are some highlights  -
>
> He worked daily as a navigationfield engineer -
> The Omega signals are propagated in a duct that
> is formed between the Earth and the ionosphere - and this
> duct is
> only about one or two wavelengths. Any change in the
> ionospheric
>  structure has an 'immediate' impact on strength and phase
> of
> the received signal. He monitored these signals - and thus
> was
> able to have and instantaneous "snapshot" of the ionosphere
> over the receiving path. Polar Cap absorption and auroral
>  events were quite evident on the East Coast by monitoring
> the
> Norwegian station. Conversely, quiet condx (stable amplitude
> and
> phase) on the path were indicative of good transatlantic
> propagation.  Further comments were made about using LORAN.
> He indicates that more info may be obtained from the US
> Naval
> Observatory - supplying latest info on all navigation
> systems,
> including Omega, VLF, loran-C and GPS.
> I found the notice of termination at
>  http://www.navcen.uscg.mil/omega
>
> And finally - @ 1900Z  3 PM local) both CFH and
> Cdn Forces 133.1 were S9+10 dB - with no fading.
> ( much better than normal at this time of day )
>
> 73
> Mitch   VE3OT
>
>