[Lowfer] Summary of Natural VLF Activity over the past day in VE7...

[Scott Tilley]

Hi All

Last evening and this morning was a very active time on VLF which 
resulted in some interesting recordings of whistler and chorus 
activity.  As a side note, DHO38 has been noted for the first time since 
I started monitoring VLF full time.  Coincidence?

Here's a summary of my day on VLF...

Here's a plot of lightning activity last evening:
http://dl.dropbox.com/u/15916951/VLF/May29/L_plot_global_map_WHISLTERS%20HEARD_may29_2011.jpg

Note the long line of storms along the coastal mountains of BC and the 
activity antipodal to VE7.  I believe these storms were the initiator(s) 
of the whistler and chorus activity last evening along with the active 
geomagnetic conditions.

Here's a couple of MP3s of the some of the many hours of activity (all 
less than 500KB unless noted):
http://dl.dropbox.com/u/15916951/VLF/May29/Whistlers_May%2029%202011.mp3
http://dl.dropbox.com/u/15916951/VLF/May29/Whistler%20Chorus_May%2029%202011_1.mp3
http://dl.dropbox.com/u/15916951/VLF/May29/Whistler%20Chorus_May%2029%202011_2.mp3
http://dl.dropbox.com/u/15916951/VLF/May29/Whistler%20Chorus_May%2029%202011_3.mp3
http://dl.dropbox.com/u/15916951/VLF/May29/Whistler%20Chorus_May%2029%202011_4.mp3
http://dl.dropbox.com/u/15916951/VLF/May29/Whistler%20Chorus_May%2029%202011_5.mp3
http://dl.dropbox.com/u/15916951/VLF/May29/Whistler%20Chorus_May%2029%202011_6.mp3

This one is 1.7MB long:
http://dl.dropbox.com/u/15916951/VLF/May29/Whistler%20Chorus_May%2029%202011_7.mp3

http://dl.dropbox.com/u/15916951/VLF/May29/Whistler%20Chorus_May%2029%202011_8.mp3

Then I went to bed with the VLF RX streaming to the computer in the 
bedroom.  Overnight the whistler activity died out and only spherics and 
tweeks where noted so I sleep well :-)

Lying in bed half asleep at dawn I started to hear what I thought was 
the birds chirping outside then realized it was in fact dawn chorus on 
the VLF RX.  It started off very subtle and built to a wonderful 
crescendo around 6:30am local time.

Here's a few minutes of the dawn chorus as it peaked (~6MB):
file:///C:/Documents%20and%20Settings/1/My%20Documents/My%20Dropbox/Public/VLF/May29/Dawn_chorus_May29_2011.mp3

You can see what chorus looks like on my long wide VLF grabber here:
http://dl.dropbox.com/u/15916951/VLF/May29/Dawn_chorus_wide_m.JPG

Here's the lightning activity from this morning at dawn (very quiet as 
you can hear on the recording):
http://dl.dropbox.com/u/15916951/VLF/May29/Dawn_chorus_lightning.jpg

The equipment used to monitor and record:
- 19 turn #16AWG 1.3m per side square loop aimed north with a current 
sensing preamp using an LT1028 opamp.  See 'thinking of ideal loops' by 
IK1ODO on the VLF.IT page...  The loop preamp is solar powered.
- I then run an unbalanced line to the shack where it is isolated and 
converted to a balanced input to a professional grade TASCAM US-122 USB 
sound card.
- Wolf's SL using the latest beta version does the rest of the heavy 
lifting from there...  I'm only using the autonotch feature and none of 
the other hummmmm suppressors within SL.  The sample rate is locked to NPM.

Here's a picture of the loop in 'action':
http://dl.dropbox.com/u/15916951/VLF/May29/IMG_2319%20%28Small%29.JPG

It was a wondrously unique day in my radio career for sure!  There are 
not many mornings you are pleasantly and subtly woken from bed by the 
sounds of nature from a radio ;-)

Enjoy es 73

Scott
VE7TIL