[SADXA] Interesting DX

[Darrel]

Hi Wes,

    Very simple equipment. The antenna is an untuned 32-turn loop on a 
vertical frame about 4 ft by 2 ft, fixed in a N-S plane. It's about 120 
ft away from the shack or any buildings, to try to keep away from VLF 
noise produced by the shack computer etc.  It's fed by about 150-ft of 
old cable-TV hardline (from a CARA hamfest), going into a preamp and 
then to the sound card in my shack PC.  Data are sampled once every 5 
seconds, with a 96k standard sound card clock rate.  Then an FFT in the 
PC produces the spectrum from ~DC to ~48 kHz.  I pick off the samples at 
the 7 chosen frequencies between ~19 and ~41 kHz, corresponding to NWC, 
NML, NAU,JJI, NLK, NAA and NPM, and store those in disk files.  [I also 
store the data at 39 kHz, which seems to be a relatively clear 
frequency, as a measure of my background noise.]  As this is all in 
software, I have all the frequencies simultaneously and there's no need 
to do any frequency switching.

  That's it.  My "receiver" is just a PC sound card.

Cheers,
     Darrel, aa7fv.



On 10/21/2022 11:54, Wes wrote:
> Hi Darrel,
>
> I thought I might hear from you.  Interesting observations.
>
> What equipment are you using for this?  I have a Perseus SDR that I 
> thought I couldn't live without but it's just sitting here.  I know a 
> lot of LF SWLs seem to like them.  Maybe I could put it to use.  How 
> are you switching frequencies and what is your antenna?
>
> Wes
>> To:
>> Southern AZ DX Association E-Mail Reflector <sadxa at mailman.qth.net>, 
>> Wes <wes_n7ws at triconet.org>
>>
>>
>> Correction:
>>    I looked at my VLF data at higher time resolution, and I *did* see 
>> an event possibly corresponding to the gamma-ray burst.
>>
>> NWC, Australia: about 1 dB "glitch" down in strength at 1320 UTC.
>> JJI, Japan:  about 4 dB "glitch" downwards at 1320 UTC.
>>
>> Nothing obvious on any of the other VLF stations I was monitoring.
>>
>> My data, and data from other observers, are archived Stanford and can 
>> be plotted:
>>
>> http://sid.stanford.edu/database-browser/browse.jsp?date=2022-10-09T13.00.00&display=vertical&goesFlareStrength=A1.0&timeRange=60&size=1000x200 
>>
>>
>> My own data are labelled "Agua-Caliente 9471".  (I live near the Agua 
>> Caliente park in Tucson.)
>>
>> Cheers,
>>        Darrel, aa7fv.
>> Subject:
>> Re: [SADXA] Interesting DX
>> From:
>> Darrel <demerson2718 at gmail.com>
>> Date:
>> 10/21/2022, 11:55
>>
>
> On 10/21/2022 11:30 AM, Darrel wrote:
>> I've been monitoring several VLF stations continuously for the last 
>> few months. I looked at my data records for October 9 around 1300- 
>> 1400 UTC.  This is a summary of what I received in Tucson:
>>
>> NWC 19.8 kHz, Australia: Strong signal, but nothing remarkable at 
>> that time.
>> NML  25.2 kHz, LaMoure North Dakota: Strong signal, nothing to note
>> NAU 40.75 kHz, Puerto Rico: Weak signal, but very steady and nothing 
>> remarkable
>> JJI 22.2 kHz, Japan: Strong signal, nothing to note
>> NLK 24.8 kHz, Jim Creek, Washington state: Strong signal. Possibly a 
>> weak glitch around 13:20 UTC, but comparable to the noise fluctuations.
>> NAA 24.0 kHz,  Cutler Maine: Strong signal, nothing to note
>> NPM 21.4 kHz, Hawaii: Weak signal, but nothing to note.
>>
>> So, for what it's worth, I didn't notice any strong correspondence 
>> with the gamma-ray burst on any of these VLF paths.
>>
>> Cheers,
>>      Darrel, aa7fv.
>>
>> On 10/21/2022 10:37, Wes wrote:
>>> Further on this.  If you look a the map in this article it's claimed 
>>> that the propagation paths to the received VLF stations was enhanced 
>>> by the gamma ray radiation and signals outside the footprint were 
>>> not received.
>>>
>>> What intrigued me was the fact that AZ was on the edge of this 
>>> footprint and this was about the time of our sunrise.  So I put the 
>>> date and time in DX Atlas and opened a rectangular map.  Lo and 
>>> behold, his gamma ray radiation footprint coincides almost 
>>> completely with the solar nighttime footprint.  Coincidence?
>>>
>>> Wes
>>>
>>> On 10/21/2022 7:29 AM, Wes wrote:
>>>> https://spaceweatherarchive.com/2022/10/17/powerful-gamma-ray-burst-made-currents-flow-in-the-earth/ 
>>>> ______________________________________________________________
>>>> SADXA Website http://www.sadxa.org
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>