Topic: Blitzortung spectrum display and interference detection

[dfroula]

I'm not sure if everyone caught this on the Blitzortung web site forum, but it is possible to retrieve a spectrum plot of the latest lightning strike reported to the servers at the following link:

http://www.blitzortung.org/Scripts_php/php_signal_2.php?station=681&region=3&mode=FFT&unit_width=2&unit_height=12

You need to enter your station ID in the URL in place of mine ("681").

This can be very useful in tracking down interference sources. The Red amp filters signals outside the 1 KHz to 50 KHz range. Most lightning detections peak around 10 KHz. Any significant peaks outside the 10 KHz area are likely from periodic noise sources. A peak can also be seen < 1000 Hz from power line noise that gets through the high-pass filter.

The plot may also reveal any problematic self-resonances in your antenna.

I also have it integrated the graph into my web site at http://projectmf.homelinux.com

You can also get the normal amplitude plot at:

http://www.blitzortung.org/Scripts_php/php_signal_2.php?station=681&region=3&mode=signal&unit_width=2&unit_height=12

Regards,

Don

[W3DRM]

Good info!

On the expanded area lightning map (map2.html), I can find no strikes plotted on the map but the graph in the lower right-hand side of the display shows activity as does the chart in the upper left corner which shows "Lightnings in the last 2 hours: 16".

Am I missing something?

[dfroula]

I noticed that too!

Looking at the maps on the Blitzortung site, there is activity in the lower right corner of the map in Kentucky that is obscured by the bar graph!

Don

[W3DRM]

Guess I didn't dig deep enough. That does explain it though - thanks!

[miraculon]

I spotted it too and built up a web page for it. I have both the "Red" and "Green" systems with waveform and FFT plots. The Red gain settings show in the plot. Interestingly there is a placeholder for it on the Green systems, but it is always "zero" 0.0. The amplifier is all analog and the gain is set by jumpers, so the controller doesn't actually "know" the gain on the Green units.

http://www.miraculon.net/signals.html

I can see a ~54KHz spur on the FFT for my old "green" system. (red E-W plot)

It is always there. I opened up the bandwidth on the green USB6.8system and currently have 10K input damping resistors (a.k.a. terminators).

Greg H.