dead air

is anyone still on this frequency

20 HP

Two real FM radios in the rack, a patch cable for an aerial. It hops your town's stations faster than you can follow: broken syllables, half a chord, then static. A channel is a semitone, so your town is a scale. When it finds a human voice it can stop and listen.

The DEAD AIR panel: black, a long strip of bare circuit board across the top under the name, marked 88 to 108 in gold ticks; below it a steel radio mast in gold dots, rising through fog from the ANTENNA jack at the foot, its top section eight bare rungs and a round lamp; TUNE and SWEEP the two big knobs either side of the mast, the jacks and small knobs round them; daylight noise at the foot.

Turn a knob: drag it or tap either side of it, roll the wheel over it or use the arrow keys; a double click puts it back. CATCH is a button: press to hold the last two seconds, again to let go. The aerial is the loose plug under the panel: drag it anywhere, hold it and your hand's on it, let go and it swings. Tab to it and the arrow keys push it, Space takes hold. The patches step on until you touch something.

A made-up town's twenty-four stations, with a dark track under them. The real one hears yours.

example patches

The dial, the map, the sound and every out and light here are DEAD AIR's engine, the module's own code, running in your browser. Only the air is made up: synthesised talk and music, a model of the radio and the cable. This town's stations sit in A minor; yours won't.

The aerial

Plug any patch cable into ANTENNA and leave the other end loose. Longer hears further. Hang it clear and faint stations come up out of the hiss; lay it against the rack and the rack's own clocks come in. Move it a hand's width and one station fades as another arrives. Hold it and you're part of the aerial.

The ladder is the signal where it's stopped; SIGNAL puts it out, so with the sweep stopped a hand near the cable moves a CV.

The dial

Switched on, it walks the band in about four seconds, and each station it finds stays on the dial as a faint mark. The bright needle is the radio you hear; the dim one is the other, already at the next stop, so a hop has no gap.

TUNE, a big knob: the dial, 87.5 to 107.9 MHz.
TUNE, the jack: 1 V an octave, where a semitone is a channel, 200 kHz. Every note is a place on the band.
SWEEP, a big knob, and its jack: how long a stop lasts. Fully left a plain radio; at noon half a second; at full 30 ms. A radio takes about 60 ms to move, so the fastest stops are slices of what it just heard.
CLOCK: the next stop. SWEEP rounds to it.
SPAN: how much of the band it walks. Fully left one frequency; at noon about an octave; at full the whole band. Nearly shut it worries at one station's edge.
STATIC: where it may stop. Fully left only on stations, a note on TUNE moving to the nearest: your town's frequencies become a scale. At noon anywhere. Fully right only where nothing is, the real roar between stations.

Someone there

STAY: how long it stops for a person. Fully left never. Turned up, it stops at each station to listen and stays while someone's talking: four seconds at noon, half a minute at full.
VOICE, a gate out: high while it hears speech, which rises and falls with its syllables and never keeps time. It takes most of a second. The lamp lights with it.

Its own note

REGEN: every stop rings on its own note, 97.7 MHz being C. Fully left off; at noon the stations pluck it; at full it howls by itself.
CHOP: cuts the sound into syllables. Fully left open; at full twelve a second, with rests. With a clock, one, two or four to the clock.

Catch

It always keeps the last two seconds. Catch them and a real voice from just now is held. The needle walks on, but every stop now plays the fragment at its own pitch, so a sequence that was hopping stations plays the same notes on what you caught.

CATCH, a lit button: press to hold, again to let go. Its jack holds while a gate's high.

What comes out

LEFT, RIGHT: each radio on its own side, so hops go across.
DIAL: where the needle is, 1 V an octave: into an oscillator, your town's scale.
HOP: a trigger on every stop. VOICE and SIGNAL as above.

Inside

One board sits 10 mm behind the panel with everything on its front, the USB-C in a notch in its left edge. The two radios stand side by side over ANTENNA, at the far end of the board from the clocks. Each dial LED has its own cell in a black printed baffle. Two small screws at the ends of the dial hold the panel's top corners.

The DEAD AIR panel: a steel radio mast in gold dots rising from ANTENNA's jack, its ladder lit and the lamp at its top on, a lit tuning dial across the top, its knobs, jacks and CATCH on.

Drag it or use the arrow keys to turn it; click it to take it apart.

Specs

Format

Width: 20 HP
Depth: 20.8 mm behind the panel
+12 V: about 120 mA dark, 155 mA in use, 182 mA at the most (estimated)
−12 V: about 8 mA (estimated)
+5 V: not used
Controls: 2 big knobs, 5 knobs, a lit button

The radio

Receivers: two Si4732, one on air, one ahead
Band: 87.5 to 107.9 MHz, 103 channels 200 kHz apart
Finest step: 20 kHz
A hop: 3 ms crossfade, about 60 ms between real hops
Memory: the last 2 s

Inputs

ANTENNA: a patch cable, its other end loose
TUNE: 1 V an octave, ±6 V, added to its knob
SWEEP: CV, 5 V the whole way, added to its knob
CLOCK: clock: the next stop, high past about 0.9 V
CATCH: gate: holds while it's high, past about 0.9 V

Outputs

LEFT, RIGHT: audio, ±5 V
DIAL: CV, ±4.25 V, 1 V an octave
SIGNAL: CV, 0 to 8 V
HOP: trigger, 5 V, 10 ms
VOICE: gate, 5 V