VLF Transmissions on Music CDs

GBR

I was testing my prototype spectrum analyzer program I had written for Linux to do some natural radio work. I was in need of some test input so I grabbed my "Tubular Bells" CD. When I started up the program I was already listening for a while. I was quite surprised to see that horizontal line in the time-frequency display ... should this be RFI ... approx. 16kHz, could be GBR/Rugby the strong british VLF transmitter ... sounds reasonable for a record made in England but I needed more evidence ... see if it is there from the beginning - and there it was ... morse code ... "VVV GBR ...", so Tubular Bells begins accompanied by GBR sending it's callsign - what a nice coincidence!

Other CDs

Of course I had a quick look at some other CDs. It turned out that quite many records from GB show traces of GBR. I found them on other works of Mike Oldfield as well as on Genesis', Nazareth's, and Cat Stevens', just to name some.

Theory

My theory is, that the interference takes place primarily at badly shielded microphones as well as guitar pickups. However, while microphones can be shielded arbitrarily well, guitar pickups can not or they would not be pickups any more.

Other Transmitters

It would be nice if we would find some other transmitters recorded as well. I had a look at Mike Oldfield's "Discovery". The cover says "recorded in the swiss alps at 2000 metres within sight of lake geneva on sunny days". Some other traces indeed - one even looks like something I can pick up here in Austria.