Saturday, August 19, 2006

Stanford SID Monitors

Hello SID group.


I'm new to SID monitoring. I installed my antenna and sid monitor August 1 and have been recording data daily. I think I see the sunrise/sunset signals and the daytime signal looks like what I've seen with other sid graphs, but my nighttime signal is consistenly low.


Also...I've seen reports of a couple of flares in the last two weeks....Aug. 18 approximatelyh 16:00 UT, for example, but do not see anything on my graph. I'm including the graph I recorded on Aug. 18 to see if this group can help me understand the low nighttime signal and why I might not be seeing flares.


Thanks.



Mike, KW4MAC

3 Comments:

Blogger Lorne Davis said...

I'm new to this game also. Our antenna has been up a few weeks, but we just now have gotten our noise level under control. I can't address why you did not see a daytime solar flare, since our transmitter, NML, was down then (and for most of this week, off and on).

I don't think that a low signal at night is unusual. Shortwave radio frequencies get attenuated more by the low D-layer ionization on their way thru to an upper level bounce, so they are stronger at night. The VLF frequencies are propagated more like in a D-layer waveguide. When the ionization decreases at night in this layer, the waveguide walls 'leak' more and the signal strength is less.

Now you'd better asked someone who knows! I'm just making what I think is a good guess.

I would guess that the relative strength of the extra ionization created by a solar flare would be a function of the existing level of ionization and the orientation of the D-layer waveguide duct with respect to the ionization oriented along magnetic field lines. In other words, I bet it can be a complex mess. I sure hope that you can get an expert reply on this!

6:26 PM  
Blogger Mike Mc said...

Thanks for the good information about sid detection and vlf propagation. Not having much problems with noise here at my qth, and daytime signals look smooth on solar-calm days, but would like to see how the sytem responds to a flare. I'm wondering if my antenna...the small design....may not be sensitive enough, so may build the larger loop.

Tnx again for info.

Mike

6:04 PM  
Blogger Lorne Davis said...

After wrestling with noise from a lightning arrestor, we got our first good day on August 20. Luckily there were 3 discernable flares that day.

I noticed them, more or less, on our traces. Then I checked the Stanford sid data site. The 'bumps' correlated. Then I found the noaa site info. Go to www.sec.noaa.gov/ftpdir/indices/events . It list solar flare events wrt UTC time. The flares are XRA events. The main levels are numeric classifications up ward from B to C to M to X. We fry at X, I guess. I think that the sidmon design should pick up C and up sized flares.

On 8/20 I saw a 1632 UTC C2.9 event and a 2110 UTC C4.3 flare. A 1953 UTC B 9.9 flare was discernable after the fact.

Hope this helps some. You can check the noa site everyday for the previous day to help setup your sid monitor. It's helping me alot.

5:22 AM  

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