OBSERVATION of HF "WHISTLERS"

[David Eckhardt]

In monitoring 19.935 MHz, I typically detect these (maybe) HF "whistlers" at best twice a month.  They shouldn't occur, but do.  It's a mystery to me what causes them.  Their signatures are much like the more traditional LF whistlers which occur in the 500 Hz range through a few kHz.     

Today I captured quite  a number of thembang....bang.....right after another, possibly due to the present conditions precipitated by the solar proton event.  I typically detect these at best, only twice a month.  I documented all this in a PDF format  document which is attached.   Please have a read of this mystery to me (and maybe science in general ??).

I'll be glad to answer any questions.  I'm distributing this document to a much wider "brain trust" than I usually would to both make others aware of this phenomenon and to gain theories regarding what causes this.   

BOTTOM LINE:  It's a mystery to me.

Dave - WØLEV

[Terry Bullett]

Dave,

It may help to know, from a propagation perspective, what a "whistler" is.  Not everyone does, and it is quite counter-intuitive.
The name comes from the sound it makes on a radio.   Observation shows these are narrow band signals that show very large time delay dispersion with frequency.
From a propagation perspective, these radio signals propagate in a magneto-plasma and  have a large part of their electric field in parallel to the magnetic field and the direction of propagation.
Somewhat similar to waveguide propagation.
 
This accounts for their ability to penetrate the ionosphere when a normal TEM will reflect, and also the high dispersion you observe.
This is 1960's Ken Davies stuff. His book is here:  https://nvlpubs.nist.gov/nistpubs/Legacy/MONO/nbsmonograph80.pdf
Back when FedGov had experts and published their work to the taxpayers.

As to how your 19Mhz signal obtained whistler mode propagation, this is curious. And unexplained. 

73,
Terry
W0ASP

--
Please follow the HamSCI Community Participation Guidelines at http://hamsci.org/hamsci-community-participation-guidelines.
---
You received this message because you are subscribed to the Google Groups "HamSCI" group.
To unsubscribe from this group and stop receiving emails from it, send an email to hamsci+un...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/hamsci/CAODdWWHH83A6035ps_%2BUTNZzW0de96RR2weBdVU5tv0Ai6GBPw%40mail.gmail.com.

-- 
Dr. Terry Bullett          WØASP 
NOAA National Centers for Environmental Information (NOAA/NCEI)
Cooperative Institute for Research in Environmental Sciences (CIRES)
Terry....@noaa.gov    720-446-9775 (google voice)  978-337-9092 (cell)   
"Life is Complex.  It has a Real part and an Imaginary part." 

[Ethan Miller K8GU]

Dave,

Interesting observations--thanks for sharing. I'll take a look at the
channel properties closely; but, perhaps you have measurements of the
delay from the broadband spheric impulse until you see the structure?
It wasn't immediately clear to me that there was a regular/consistent
pattern of occurrence.

Have you verified that it's not an out-of-band (or a spurious mix with
a broadcast carrier, but you'd probably see modulation on that) RF
industrial heater or plasma source? These often have a hook-like
shape due to the feedback control system that dials in the frequency
for optimal heating/welding. Example:

https://www.sigidwiki.com/wiki/RF_heating_and_welding_interference

Interesting signature that deserves some investigation for
sure...thanks for sharing!

73,

--Ethan, K8GU.

> --
> Please follow the HamSCI Community Participation Guidelines at http://hamsci.org/hamsci-community-participation-guidelines.
> ---
> You received this message because you are subscribed to the Google Groups "HamSCI" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to hamsci+un...@googlegroups.com.
> To view this discussion visit https://groups.google.com/d/msgid/hamsci/CAODdWWHH83A6035ps_%2BUTNZzW0de96RR2weBdVU5tv0Ai6GBPw%40mail.gmail.com.



--

http://www.k8gu.com/
Repair. Re-use. Re-purpose. Recycle.

[Dave Typinski]

Hi David,

Thanks for that PDF, very interesting.

These are /very/ reminiscent of the farkles we see all over the HF band. Same
time scale, but much wider in freq range than yours. For lack of a better
descriptor, the term "farkles" was coined by Dolores Krausche at the UF Radio
Observatory in the 1970s.

See page 28 here:
https://www.aj4co.org/Publications/The%20HF%20Spectrogram,%20Typinski%20%282017%29%20Slides%20and%20Notes.pdf

Supposedly, these signatures are known in the FMCW radar industry; they are
supposedly spurs that occur when a radar transmitter is commanded to
instantaneously step from one freq to the next.

One also wonders if they could be spurs from industrial (induction) or medical
(diathermy) RF heating units turning on and off.

It sure would be nice to have a definitive explanation of these emissions.
--
Dave Typinski
AJ4CO Observatory

> Dave - WØLEV*
> *
>
>

[Jonathan]

Ethan,

Any sferics seen at that frequency would be local, around 500 km or so and usually less, and whatever these observations are don't appear to have any relation to sferics. The curve is also quite imperfect and does not follow Eckersley's law.

Jonathan

--
Please follow the HamSCI Community Participation Guidelines at http://hamsci.org/hamsci-community-participation-guidelines.
---
You received this message because you are subscribed to the Google Groups "HamSCI" group.
To unsubscribe from this group and stop receiving emails from it, send an email to hamsci+un...@googlegroups.com.

To view this discussion visit https://groups.google.com/d/msgid/hamsci/68AE8CCC.3010007%40typnet.net.

[Ethan Miller K8GU]

Jonathan,

Right--the features I referred to as "spherics" are the impulsive
static crashes, not the hook-shaped feature. These definitely
propagate over long distances, although they're certainly stronger.
If we were to zoom (figuratively, lacking raw data) in on them in
time, they should have the (pseudo)impulse response of the skywave
channel, as described in this paper, and replicated recently by the
Duke ECE lightning group with less-sophisticated equipment:

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018RS006680

I think we're in agreement that the timescales of the data that (the
original) Dave presented do not suggest a lightning source for the
hook-shaped structure. My view is that it is RFI; but, I'm willing to
be convinced otherwise.

--Ethan.

> To view this discussion visit https://groups.google.com/d/msgid/hamsci/CAOY0kB3%3Da6tC2cZ%2BzuRg7ajADt%2BAivSek8nm%3DGcoGvXHf6_UKA%40mail.gmail.com.

[Jonathan]

Ethan,

Because of the path loss, distant sferics at those frequencies are often below the noise for someone without access to the HF antenna array described in the paper. The lines in the spectragram could also be impulsive interference not originating from lightning. I agree that what that is could be interference or doppler reflected signals from meteor trails or aircraft.

Jonathan

To view this discussion visit https://groups.google.com/d/msgid/hamsci/CAFkosZLQAXn1Yu9BvVVTM9%3Dq9MUU%3Dzui%3DuxR2pFU9stk3CRvBA%40mail.gmail.com.

[David Eckhardt]

I did a baddie with the "fat finger syndrome" and lost some 25 replies to my posting addressing the observations of possible HF "whistlers".  If anyone has that thread, please forward it to me.  I was going to reply to each one, but the copy/paste zeroed out the thread.  Maybe I need a new mouse?   ggrrrrr........

Dave - WØLEV

On Tue, Aug 26, 2025 at 9:23 PM W0LEV via groups.io <davearea51a=gmai...@groups.io> wrote:

In monitoring 19.935 MHz, I typically detect these (maybe) HF "whistlers" at best twice a month.  They shouldn't occur, but do.  It's a mystery to me what causes them.  Their signatures are much like the more traditional LF whistlers which occur in the 500 Hz range through a few kHz.     

Today I captured quite  a number of thembang....bang.....right after another, possibly due to the present conditions precipitated by the solar proton event.  I typically detect these at best, only twice a month.  I documented all this in a PDF format  document which is attached.   Please have a read of this mystery to me (and maybe science in general ??).

I'll be glad to answer any questions.  I'm distributing this document to a much wider "brain trust" than I usually would to both make others aware of this phenomenon and to gain theories regarding what causes this.   

BOTTOM LINE:  It's a mystery to me.

Dave - WØLEV

_._,_._,_

---

Groups.io Links:

You receive all messages sent to this group.

View/Reply Online (#2336) | Reply to Group | Reply to Sender | Mute This Topic | New Topic
Your Subscription | Contact Group Owner | Unsubscribe [davea...@gmail.com]

_._,_._,_

--

Dave - WØLEV