Long-Baseline Stereo natural VLF radio recordings

27 September 2001, 1100 UT (0400 PDT/0500 MDT): California - Colorado; California - New Mexico

Three VLF researchers, Mike Mideke in western New Mexico, Shawn Korgan in northeastern Colorado, and Steve McGreevy in eastern California, simultaneously recorded natural VLF radio at 1100 and 1200 UT. While activity was very low and only a few whistlers were occurring along with weak chorus, we did record similar activity. Mideke and McGreevy used Sony Mini-disc recorders allowing for an exact matching of the atmospherics, and Shawn Korgan used a cassette machine, requiring digital manipulation of his recording, which was found to be approx. 0.2% slow. Combining the audio segments from Mike and Shawn was a very time consuming and computer resource intensive, and so far I have matched only two segments presented herein.

1) New-Mexico/California:A rather loud 440Hz tone at 1100:00 UTbegins the simultaneous recording. The RIGHT channel is e. California near Darwin, and the LEFT channel is near Magdelena, w. NM. Duration 2:19 - 1100nmca.mp3 - 2.13 MB at 128 kbps

2) California/Colorado also beginning at 1100 UT. Chorus and hissband is stronger in the Colorado (near Greeley) recording in the RIGHT channel versus eastern California (near Darwin) recording in the left channel. Duration 2:19 - 2) 1100caco.mp3 - 1.59 MB at 128 kbps.

3) Clearer .WAV-file recording of the 1100:01 to 1100:12 UT California vs. Colorado segment of a weak whistler. 11zcaco5.wav - 11 seconds at 16-bit/22050 Hz sampling rate, 959 KB

Both the California and Colorado recordings were made on e-field receivers using vehicle-mounted whip antennae. Mike's New Mexico recording in the LEFT channel was originally a stereo file that I converted into a mono file by combining right and left channels from two cross-azimuth large wire-loop antennas he used to make his original recording. It was made into a mono file and then transferred into the left channel of this stereo audio file. My recorded segment from eastern California using a non-directional e-field antenna and WR-4b receiver is in the RIGHT channel.

Audio samples from "Auroral Chorus III" a double-CD album to be released in early 2002. S. P. McGreevy

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