Field Recordings - Sky
Early in the research process, I wished to explore the methods in which humans tune into electrical signals present in the atmosphere via electrical technology itself. My focus was to hand-build radio receivers to get a better understanding of how each component functioned, and attempt to get my head around a tiny component's relationship (geometrical, material, electrical, magnetic, etc) to the outside world. How does a coil 'hear'? How does the antenna intercept waves? What relationship does the ground have to the rest of the circuit, or the actual earth for that matter? Although there was plenty of information on 'how a circuit works' technically, there is space to consider individual energetic relationships within a larger system, an ecology as such. Radio circuits are particularly intriguing as their internal electrical environment somehow meets and expresses an external electrical environment.
Much of this fascination was propelled by Daphne Oram's highly imaginative treatment of transmitter and receiver circuits in her book An Individual Note of Music, Sound and Electronics.
Process
Below is documentation of the 'Steve McGreevy' VLF receiver I constructed.
Circuit schematic for a electric field VLF receiver.
Romero, Renato. Radio Nature: The Reception and Study of Naturally Originating Radio Signals. Great Britain: The Radio Society of Great Britain, 2008, pg. 61.
The inductors in this circuit were not commercially available, at least not easily, so I had help making them from scratch. Inductors are basically coils of insulated wire (hence why they are commonly known as coils). They are seen in the circuit as wiggly lines, 160mH and 100mH, and they act to tune the frequency of the VLF receiver. More wire results in larger frequencies, although how they are placed in relationship to each other in the circuit creates a certain ratio between them. Often a magnetic core is added to boost the inductance (saving wire and real estate). Technically this turns them into ferro-inductors. I had loan of a inductance meter so I was able to 'tune' these components to the recommended value by adding more or less turns of wire around the ferro-magnet.
After a bit of troubleshooting, the circuit actually worked! It transduced electromagnetic signal emanating from nearby electrified objects and transformed the signal into hums, bleeps, pulses, crackles, chatterings, and a range of other sounds. The audio quality was surprising clear and crisp. Field Recordings - Earth is a related project that also uses the homemade VLF box.
There is never a silent electrical moment in the urban environment - our buildings, streets, and open spaces are coiled with the copper wires of electrical infrastructure, and buzzing with airborne wireless signals. The real test was to take the box out of this human-made electrified environment to see if it was sensitive enough to intercept naturally occurring electromagnetic signal. This meant traveling as far away as possible from the reach of power grids and other human-created radio transmission. For this, I chose to travel to Southport, the most southern town in Tasmania. In travelling to a higher latitude there was also the slight potential I may catch a glimpse (or even better, a recording) of the electromagnetic shower of the aurora australis -- forecast to peak at the time of my visit.
Unfortunately I wasn't treated to any shows of the aurora. However, the box worked extremely well. The above photos show the landscape where I did the majority of my field recordings: on an open beach and out in a field (to avoid the shadow effect caused by trees). However the best recordings were done in these locations in pitch black darkness just before dawn. It was at this time that the electromagnetic pings, crackling and tweaks intercepted were at their most rowdy.
Below are examples of the recordings I made on this trip.
In Test, a constant rhythmic ticking can be heard (to this day I don't know what the ticking is, and it was present in all areas of the town. I've not heard this in other urban environment). Half way through through the recording, the radiant twitching of an exit sign can be heard.
The below audio was recorded at approximately 4:30am on a beach in Southport. I believe that these sounds are a combination of sferics and tweeks.
"Tweeks result when sferics are ducted in the earth-ionosphere waveguide distances much greater than a couple of thousand kilometers. The distance can be as great as halfway around the earth (20,000 kilometers). When ducted over large distances, the VLF radio waves undergo a process called dispersion - that is the higher frequencies travel slightly faster than the lower frequencies. This is especially true of the frequencies between 3 and 2 kilohertz. Tweeks sound much different than sferics. Instead of the sharp crackling sound, tweeks have a quick musical sound somewhat like the ricochet sound bullets make (at least in the movies)." - INSPIRE project