Omega - End of an Epoch

Omega Visit with Gail West, Sept. 23, 1993

And information on the Russian ALPHA Radionavigation System

Omega shut down 30 September 1997! Here's an edited copy of my report e-mailed to a few other people and also a spectrogram made of the tape right after (this has been updated 03 January 2012 with recording and another spectrogram):

Well, I got a nice recording of Omega's last beeps 30 Sept. 1997 at 0300z, and also two nights of nice whistlers too, especially this morning, 01 October 1997, between 1100-1330 UT. There was also some intermittant dawn chorus starting at about 1230 UT and going until after 1500 UT - I had not yet caught chorus this summer or fall until now, so I was really glad to hear some chorus even though it was not very strong, and overall a really nice 2 days of whistler listening. Many whistlers this morning (October 01) had echoes too. The whistlers seemed to be generated by fairly nearby lightning - not too local but within 1000 miles.

I started recording at 0257 UT 30 Sept. I made a WWV time check at 0259z on the tape and then let it run with the WR-4b whistler receiver set to high-pass--lots of Omega into the Marantz PMD-212 tape recorder. At about 0259:30, Omega D (North Dakota) shut down, leaving Omega-C Hawaii going for about 2-3 more of its cycles. About 0300 (or within a few seconds) and after its two 11.8 kHz beeps, Omega C went off. Both D and C did not shut off abruptly, but did a sort of 'fade-out' over a 1-2 second period. Interestingly, going over the tape in slow motion revealed a third, very weak Omega station running on until a minute or so later - the 10.2 kHz beep was noticed. Probably H-Japan, the next strongest station here in Califirnia usually.

By 0301 UT, all that was left was the Russian Alpha system - short beeps in clusters of three beeps, a pause, then three beeps again in downward frequency steps. Russian Alpha is much weaker and higher up in frequency (up to 14.1 kHz) then Omega was and has a far lower duty-cycle, and so the natural radio band is really MUCH cleaner sounding suddenly! It's also fun to observe Alpha propagation - I guess the strongest one I get is from Siberia (KO - see ALPHA article this link)--it is stronger toward sunrise than at any other time of the day by 3-6 dB or so.

The spectrogram above shows Omega Station "D" North Dakota, and Omega Station "C" Oahu, Hawaii with their last beeps. Recorded on my van-based WR-4b VLF receiver with 2 meter whip antenna up 3 meters high. The tape was made on a Marantz PMD-212 with cromium tape and the WR-4b in high-pass/emphasis mode.

The tape was copied into a sound file at 44.1 kHz/16 bit. Then it was FFT filtered in Coolwave 1.5 and 9 to 14 kHz was emphasised by 15 dB. Then I ran a spectrogram on it and then edited the spectrogram adding the labels.

Update 03 January 2012 - recordings and another spectrogram below added:

5.2 MB .WAV file mono - 16-bit 44.1 kHz sampling rate recording of this shutdown - (1:02)

Omega "D" North Dakota Visit - Sept. 1993
a very nice bunch!:

Natural VLF Radio Homepage

Stephen P. McGreevy
P.O. Box 928
Lone Pine, CA 93545-0928 USA

Originally written in Dec. 1997; revised April 2007

Visits since 11 April 2007:  

Non-Directional Beacon (NDB) Gallery - 1984 to 2006

LowFER and MedFER Experimenter Folks during the late 80's Heydey