X-Ray flare observations with Gnu Radio software

Some of you know that among my various activities involving the
application of radio to space science, I operate a VLF receiver, called
SIDsuite, that is a Gnu Radio based application.

Today, sunspot group 1302 has been putting on a great show, and I wanted
to share the plot of one of the VLF paths I monitor, which is
strongly affected by solar X-Ray flare activity, due to X-Ray flux
changing the refractive index of the ionosphere.

Sunspot group 1302: a party animal


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On 24/09/11 05:33 PM, Nick F. wrote:

Marcus,

Very cool stuff! Can I ask about the hardware you’re using with SIDsuite?

–n

Highly sophisticated, top-secret alien-inspired technology :slight_smile:

Actually, a 1.5M wide square-loop antenna, with about 80M of 22ga wire
on it. Feeding a
Behringer Mini-MIC microphone preamplifier, then into my 96KHz sound
card.

http://www.behringer.com/EN/Products/MIC800.aspx


Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

On 25/09/11 08:29 AM, Patrik T. wrote:

I use a square-loop antenna, roughly 1.5M in diameter. I have roughly
80M of 22ga wire wound onto it.
This feeds a Behringer Mini-Mic 800 microphone preamplifier, which is
then fed into a 96KHz sound
card–no USRP required.

The software I wrote for this I call SIDsuite. It’s available via
GitHub:

https://github.com/patchvonbraun/SIDSuite

It works by measuring the received signal stength for various VLF
transmitters–most of them are indeed
submarine communications systems. The signal strength follows a
diurnal pattern involving solar
radiation and the D and E layers of the ionosphere. When there are
strong solar X-ray events, that
pattern is disturbed–sometimes spectacularly.


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On 09/24/2011 08:14 PM, Pace VanDevender wrote:

Marcus, this is amazing data. What frequencies are in your VLF band?

Pace

That particular trace was at 24KHz–looking at the NAA station in
Cutler, Maine.

Here is the data for NML, at 25.2Khz, located in LaMour, North Dakota:

NML data for 20110924

You can see that the response is absorptive, rather than reflective, and
less intense, along this very-much-longer path between
my receiver and the transmitter in North Dakota. In particular, the
M7 at 15:20 UTC isn’t even visible in this data, because the Sun
angle at the transmitter site was probably “all wrong” to get a
strong response at that time of day.

I monitor several different frequencies, and submit data to the Stanford
SID data center every day. With my 96KHz sound card, and loop
antenna, I can “see” from a few hundred Hz to around 45KHz or so.

Many thanks for the info.

Will try it!

Patrik
----- Original Message -----
From: Marcus D. Leech
To: [email protected]
Sent: Sunday, September 25, 2011 17:04
Subject: Re: [Discuss-gnuradio] X-Ray flare observations with GnuRadio
software

On 25/09/11 08:29 AM, Patrik T. wrote:
Most interesting,

Tell us more how you did it.
- antenna used?
- daugherboard?
- etc

Many SDR users in Northern Scandinavia are up day and night 

listening on submarine traffic on VLF.

I use a square-loop antenna, roughly 1.5M in diameter. I have roughly
80M of 22ga wire wound onto it.
This feeds a Behringer Mini-Mic 800 microphone preamplifier, which
is then fed into a 96KHz sound
card–no USRP required.

The software I wrote for this I call SIDsuite. It’s available via
GitHub:

https://github.com/patchvonbraun/SIDSuite

It works by measuring the received signal stength for various VLF
transmitters–most of them are indeed
submarine communications systems. The signal strength follows a
diurnal pattern involving solar
radiation and the D and E layers of the ionosphere. When there are
strong solar X-ray events, that
pattern is disturbed–sometimes spectacularly.


Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org

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