Dunedin Aurora

2020 Edition

Experimental Prototypes

This page is for prototype data, instruments, and software. Usually I'm just testing that gadgets are recording and displaying whatever data they're receiving. While this is happening, I'm also looking to see if there are any common trends appearing, especially during space weather events.

amplitude of power harmonics susceptible to geomagnetic interference.

The input signal is processed with a hum-filter to remove 50hz mains hum, a de-noiser to remove spherics, and a notch filter for any residual man-made noise. Sample rate: 10 seconds. In spite of this, very strong interference can still filter thru as large jumps in amplitude. The local ripple control signal is visible early evening/morning as a double spike.
The resulting data is de-trended by comparing each data-point against the average trend of the whole data (3 hour window). Bars for +/- 1 and 2 standard deviations are also plotted.
The signal is galvanically isolated and amplified, before being fed into the MIC-IN port of a computer. "Theoretically" it can detect geomagnetic micropulsation and is more sensitive than "Frankencoil 1" a solenoid-like device built from car ignition coils.
The urban location and noise from domestic power (Mains hum and household appliances) blunt most of it's sensitivity at the moment. In spite of this, I'm attempting to see if any effects from space weather events can be detected, directly or by proxy.

Induction Magnetometer - 2 hr Spectrum

Frankencoil 2 is an experimental air-core induction loop designed to listen for the presence of very low frequency (VLF) signals present when space weather impacts the Earth's magnetic field.

Frankencoil is made from four boxes of network cable (330m of cable per box, each cable contains eight wires) wound into a loop three metres in diameter. All of the wires in each cable are joined to make a single, continuous, scramble-wound loop of approx 1000 turns.

The urban location means that domestic and mains noise presents significant magnetic "fog" that bleeds down from higher frequencies. Isolated low frequency noise that starts down low, is hopefully a signal of geomagnetic unrest. This image is a frequency spectrum for the last 2 hours, with 0-4hz band displayed for signals and 0-500hz band displayed for context.

A 2 hour spectrum of VLF radio noise is included for comparison.