Signals from Nowhere

Tonight I heard something that shouldn't exist.

Every radio operator knows the rules. The electromagnetic spectrum has boundaries. Below a certain frequency, signals don't propagate the way we expect. The noise floor overwhelms everything. Practical radio communications start around 3 kHz and go up from there.

0.5 MHz—500 kHz—is the old maritime distress band. It's monitored but mostly quiet these days. I scan it sometimes out of habit.

Tonight, at 2:17 AM (that time again), I picked up a carrier signal at 0.47 MHz. Not 470 kHz on a standard band—0.47 MHz on a frequency that shouldn't carry any signal at all at the power levels I was detecting.

The signal was strong. Too strong for that frequency. Like someone had figured out how to broadcast on a channel that physics says should be dead air.

The content? I wish I could tell you. It wasn't voice. It wasn't data. It was... tonal. Long, slow sweeps up and down the audible range, like someone testing a synthesizer in slow motion.

Each sweep lasted exactly 47 seconds.

I recorded 17 minutes before the signal vanished. When I played it back, the recording was there, clear as day. But my equipment logged no signal during that time. According to my meters, I was recording static.

I heard what I heard. My equipment says otherwise.

One of us is wrong. And I'm starting to suspect it's not me.

I'm going to try again tomorrow night. Same time, same frequency. If you have equipment that can tune that low, try listening. Maybe I'm picking up something local. Maybe it's more widespread.

I need to know I'm not alone in hearing this.