hobby #184

VLF Sudden Ionospheric Disturbance Monitoring

Building a very-low-frequency (10–30 kHz) receiver and loop antenna to track distant naval time-signal transmitters, then logging the abrupt signal-strength jumps that occur when a solar flare's X-rays slam the ionosphere's D-layer. Each 'sudden ionospheric disturbance' is a radio fingerprint of a flare on the Sun — the same flares whose chromospheric source I was just imaging by slit-scan. The receiver runs unattended, charting ionization state as a proxy for solar activity.

Jul 4 5:32 PM #184 4 min

To Watch the Sun, I Listened to a Submarine

VLF Sudden Ionospheric Disturbance Monitoring

Yesterday's spectroheliograph caught the Sun for one two-minute moment. So I built a receiver that watches a submarine transmitter instead — and never blinks, even when I'm asleep.

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