SciFi-XZBT/telemetry_elements.md

Telemetry Audio Elements

Catalog of the discrete telemetry sounds the application produces. All of them live in TelemetrySynth (js/audio.js, ~line 715) and are synthesized at runtime from Web Audio oscillators, envelopes and filters — there are no samples anywhere in this project.

Telemetry is the "computer chatter" layer: short, non-musical-foreground blips that sit on top of the continuous hull / warp / life-support beds. It is the only audio layer with a density parameter, because it fires as discrete events rather than running continuously.

---

Element catalog

Element	Method	Description	Where used
LCARS Single Chirp	synthesizeLCARSSingleChirp(pitch?)	Soft sine touch tone, ~90 ms, gentle 8 ms attack into exponential decay, with a subtle 2% downward pitch glide and a 3.2 kHz lowpass to kill the click. Accepts an optional pitch, which makes it the building block for the other LCARS elements.	TNG auto-scheduler (45%), DS9 (50%), soundboard btn-chirp-single / btn-switch-pop, preset-change confirmation while playing, default fallback for any unmapped soundboard or event id
LCARS Double Chirp	synthesizeLCARSDoubleChirp()	Two single chirps 65 ms apart, second pitch two steps up the LCARS scale (minor third / fourth). The iconic "acknowledged" tone.	TNG auto-scheduler (30%), Voyager (60%), soundboard btn-chirp-double, engage/play confirmation for non-Whoniverse, non-bioship universes
LCARS Acknowledgment Sequence	synthesizeLCARSSequence()	Three chirps at 75 ms spacing drawn from overlapping windows of the LCARS scale — reads as a short data-accept run rather than a single button press.	TNG auto-scheduler (15%), soundboard btn-chirp-ack
Sensor Sweep	synthesizeSensorSweep()	380 ms sine glide from 1200–2000 Hz, ramping either up ×1.6 or down ×0.65 at random. Longer and more "scanning" than the chirps.	TNG auto-scheduler (10%), Voyager (40%), soundboard btn-chirp-sweep, layered under btn-scanner
TOS Computer Warble	synthesizeTOSWarble()	450 ms of detuned triangle + sawtooth (fundamental and its fifth) under a 14–22 Hz vibrato LFO, through a Q=3.5 bandpass at 1.2× the fundamental. Vintage 1960s analog computer voice.	TOS auto-scheduler (60%)
TOS Relay Click	synthesizeTOSRelayClick()	25 ms square wave falling 1400 → 300 Hz. A mechanical solenoid snap, not a tone.	TOS auto-scheduler (40%)
Cardassian Sensor Tone	synthesizeCardassianSensor()	550 ms pair of sines a tritone apart (×1.414) for deliberate metallic dissonance, base 420–620 Hz. Cavernous, alien, unresolved.	DS9 auto-scheduler (50%)
NX Hydraulic Relay	synthesizeNXRelay()	40 ms triangle falling 750 → 120 Hz. Heavier and duller than the TOS click — 22nd-century industrial rather than mid-century electrical.	NX auto-scheduler (50%)
NX Indicator Beep	synthesizeNXIndicatorBeep()	80 ms 950 Hz sine with a flat sustain plateau and a fast tail. Plain and utilitarian; no glide, no scale membership.	NX auto-scheduler (50%)
TNG Door Chime	synthesizeDoorChime()	Two overlapping sines, A5 (880 Hz) then D6 (1174.66 Hz) at +160 ms, each with a long 450–700 ms decay. The "come in" chime.	Soundboard btn-chirp-door only — never fired by the auto-scheduler

---

The auto-scheduler

startAutoTelemetryScheduler() self-reschedules after every sound:

baseDelay = 12000 * (1.05 - density)   // ms
interval  = max(800, baseDelay + random(0..4000))

• density 0 → scheduler does not arm at all (<= 0.01 returns early).
• density 1 → ~0.6 s base + jitter, floored at 800 ms — a busy bridge.
• Mid values land in the 2–12 s range the parameter comment describes.
• Density comes from the active preset's telemetry.density and is also live on the slider-telemetry-density UI control.

Era routing

playRandomTelemetrySound() picks an element by params.era. Each era draws from exactly two or four elements — this is the table to extend when adding an era or a new element.

Era	Elements and weights
tng (also the default)	Single Chirp 45% · Double Chirp 30% · Acknowledgment Sequence 15% · Sensor Sweep 10%
voyager	Double Chirp 60% · Sensor Sweep 40%
tos	Computer Warble 60% · Relay Click 40%
ds9	Cardassian Sensor 50% · Single Chirp 50%
nx	Hydraulic Relay 50% · Indicator Beep 50%

Note the era is a telemetry property, not a universe property: it is set per preset in js/config.js (telemetry.era) and is independent of the universe that governs the visuals. In practice every preset in every universe uses one of these five Trek eras, so non-Trek themes play Trek telemetry — see Preset → telemetry era reference for the full per-preset mapping.

---

The activity event contract

Every scheduled telemetry sound dispatches a window event after it plays:

window.dispatchEvent(new CustomEvent('scifi-telemetry-activity', {
  detail: { era, density, firedAt }
}));

js/app.js listens for this and calls triggerObservationActivity('telemetry'), which is what synchronizes observation-mode transient visuals to the audio. The visual side deliberately treats the pulse as abstract activity — no specific beep means a specific thing on screen. The observation activity slider then gates whether a given pulse becomes visible:

responseChance = 0.18 + activity * 0.82

Important: only playRandomTelemetrySound() dispatches the event. Elements triggered directly (soundboard, play/stop, preset change) are silent as far as the visual layer is concerned. If a new element should drive visuals, it must either be reachable through the era router or dispatch the event itself.

---

Pitch material

Two fixed scales are the source of all pitched telemetry. Reuse them rather than inventing loose frequencies — they are what makes the layer sound coherent.

• lcarsPitches — 12 entries, 880 Hz → 2637 Hz, a pentatonic-flavored set built on perfect fourths and fifths. Used by every LCARS element.
• tosFrequencies — 9 entries, 440 Hz → 2217 Hz, wider and more angular, matching the era's less "designed" sound.

Unpitched elements (relay clicks, sweeps, the Cardassian tone) generate their own frequencies and intentionally sit outside both scales.

---

Signal-chain conventions

Every element follows the same shape. Match it when adding one:

1. Bail out early on !ctx || !this.gainNode.
2. Capture const now = ctx.currentTime once and schedule everything relative to it — never use setTimeout for sample-accurate timing (it is used only for the deliberate multi-note spacing in the double chirp and sequence).
3. Build oscillator → per-voice envelope gain → optional filter → this.gainNode.
4. Envelopes start at 0.001, linearRampToValueAtTime up, then exponentialRampToValueAtTime down to ~0.0001. Never ramp exponentially to or from exactly zero.
5. Peak envelope gain stays in the 0.18–0.35 band so no element dominates the bed. Clicks sit at the top of that range because they are so short.
6. Explicitly stop() every node at the end of its life. Nothing here loops.

this.gainNode carries the layer volume and connects to am.compressor, so individual elements should never touch master volume or the destination.

---

Related but not telemetry

Short event sounds for non-Starfleet universes live in sibling classes and are routed by handleSoundboardTrigger() in js/app.js. Check these before adding a new telemetry element — the sound you want may already exist:

• WhoniverseAudioSynth — sonic screwdriver, fast return, demat switch, telepathic chime, cloister strike.
• ExpandedSciFiAudioSynth — DRADIS ping, HAL chime, Geiger burst, docking clamp, improbability flip, cheerful door, and the various drive effects.
• AlertSynth — red/yellow alert cycles and the warp jump swell. Alerts are a separate layer with its own trigger path, not telemetry. They are not purely user-triggered: in Observation Mode the cinematic director's Hull Breach sequence calls alerts.triggerRedAlert('tng') on its own, roughly 6.5 s before restoring the previous state. It is in the sequence pool for the military, outlaw and industrial universes and fires on a random timer (45–75 s for the first sequence, 90–180 s between later ones). This is the only non-telemetry sound in the app that can start without user action.

Preset changes and play/stop pick between these three families by activeUniverseId — see js/app.js around lines 305–365.

---

Adding or reusing an element

Reuse an existing element when the need is generic UI feedback — the Single Chirp and Double Chirp are explicitly the neutral confirm/acknowledge sounds and are already the fallbacks for unmapped ids. Reaching for them costs nothing.

Invent a new element when the sound must carry era or universe identity that no existing element has. In that case:

1. Add the method to TelemetrySynth following the signal-chain conventions.
2. Give it a doc comment naming the era and the physical thing it imitates — every existing element has one.
3. Wire it into the playRandomTelemetrySound() era switch with an explicit probability, or leave it manual-only (like the Door Chime) if it is too characterful to fire unattended.
4. If it is manual-only, add a soundboard case in handleSoundboardTrigger() and a button in index.html.
5. Reuse lcarsPitches / tosFrequencies if the element is pitched and belongs to those eras.
6. Keep the duration under ~600 ms. This is an ambient layer; anything longer reads as a foreground event and belongs in AlertSynth instead.

---

Preset → telemetry era reference

telemetry.era is assigned per preset, and it is the only thing that decides which elements the auto-scheduler fires. It is not derived from the universe. All 70 presets across all 10 universes currently use one of the five Star Trek eras, so non-Trek universes play Trek telemetry: a retrofuture profile can chatter in TOS warbles, and a living-ship profile can ring with the Cardassian sensor tone. If you hear a sound that seems foreign to the theme you are on, this table is where to look it up.

Era	Elements fired
tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
voyager	Double Chirp 60% · Sensor Sweep 40%
tos	TOS Computer Warble 60% · TOS Relay Click 40%
ds9	Cardassian Sensor 50% · Single Chirp 50%
nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%

Starfleet Command (10 presets — ds9 ×2 · nx ×1 · tng ×3 · tos ×2 · voyager ×2)

Preset	Era	Elements heard
Enterprise-D: Main Bridge	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
Enterprise-D: Main Engineering	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
Enterprise-D: Crew Quarters	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
USS Voyager: Bridge	voyager	Double Chirp 60% · Sensor Sweep 40%
USS Voyager: Class-9 Warp Core	voyager	Double Chirp 60% · Sensor Sweep 40%
USS Defiant: Tactical Bridge	ds9	Cardassian Sensor 50% · Single Chirp 50%
Deep Space 9: Ops Center	ds9	Cardassian Sensor 50% · Single Chirp 50%
Enterprise NCC-1701: Bridge (TOS)	tos	TOS Computer Warble 60% · TOS Relay Click 40%
Enterprise NCC-1701: Engineering (TOS)	tos	TOS Computer Warble 60% · TOS Relay Click 40%
Enterprise NX-01: Command Bridge	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%

The Whoniverse (7 presets — ds9 ×1 · nx ×1 · tng ×2 · tos ×1 · voyager ×2)

Preset	Era	Elements heard
1963 Classic Console (1st / 2nd Doctors)	tos	TOS Computer Warble 60% · TOS Relay Click 40%
Victorian Secondary Console (4th Doctor)	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
The Coral Living TARDIS (9th / 10th Doctors)	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
The Copper Workshop (11th Doctor)	voyager	Double Chirp 60% · Sensor Sweep 40%
The Cold Machine (12th Doctor)	ds9	Cardassian Sensor 50% · Single Chirp 50%
The Singing Crystal Console (13th Doctor)	voyager	Double Chirp 60% · Sensor Sweep 40%
The Infinite White (14th / 15th Doctors)	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%

Industrial (8 presets — ds9 ×1 · nx ×3 · tos ×3 · voyager ×1)

Preset	Era	Elements heard
USCSS Nostromo: Ore Refinery Bridge	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Serenity: Firefly-Class Cargo Hold	tos	TOS Computer Warble 60% · TOS Relay Click 40%
Red Dwarf: Main Drive Corridor	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Starbug 1: Cockpit Environment	tos	TOS Computer Warble 60% · TOS Relay Click 40%
The Raza: Dark Matter Bridge	ds9	Cardassian Sensor 50% · Single Chirp 50%
Rocinante: Combat Ops & Epstein Drive	voyager	Double Chirp 60% · Sensor Sweep 40%
Eagle Transporter: Command Module	tos	TOS Computer Warble 60% · TOS Relay Click 40%
Valley Forge: Agro-Dome Forest Hub	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%

Bioships (6 presets — ds9 ×1 · nx ×2 · tng ×1 · voyager ×2)

Preset	Era	Elements heard
Moya: Leviathan Central Nexus	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
Talyn: Gunship Neural Bridge	ds9	Cardassian Sensor 50% · Single Chirp 50%
The Lexx: Primary Organ Bridge	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Vorlon Cruiser: Sentient Core	voyager	Double Chirp 60% · Sensor Sweep 40%
Wraith Hive Ship: Throne Chamber	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Species 8472: Fluidic Bioship	voyager	Double Chirp 60% · Sensor Sweep 40%

Retrofuture (8 presets — nx ×2 · tng ×2 · tos ×3 · voyager ×1)

Preset	Era	Elements heard
Jupiter 2: Upper Deck Astrogator	tos	TOS Computer Warble 60% · TOS Relay Click 40%
The Liberator: Zen Flight Bridge	tos	TOS Computer Warble 60% · TOS Relay Click 40%
USS Cygnus: Victorian Engine Hall	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
USS Palomino: Deep Research Pod	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Discovery One: Habitation Centrifuge	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
Dark Star: Bomb Bay & Quarters	tos	TOS Computer Warble 60% · TOS Relay Click 40%
Gunstar: Tactical Combat Cockpit	voyager	Double Chirp 60% · Sensor Sweep 40%
The Searcher: 25th Century Flagship	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%

Military (7 presets — ds9 ×3 · nx ×1 · tng ×1 · voyager ×2)

Preset	Era	Elements heard
USS Sulaco: Conestoga Hangar Deck	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Battlestar Galactica: Combat Information Center (CIC)	ds9	Cardassian Sensor 50% · Single Chirp 50%
White Star: Minbari/Vorlon Hybrid Bridge	voyager	Double Chirp 60% · Sensor Sweep 40%
EAS Agamemnon: Omega Destroyer Bridge	ds9	Cardassian Sensor 50% · Single Chirp 50%
Andromeda Ascendant: Command Deck	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
Excalibur: Victory-Class Heavy Combat Core	ds9	Cardassian Sensor 50% · Single Chirp 50%
Colonial Viper Mk II: Cockpit Atmosphere	voyager	Double Chirp 60% · Sensor Sweep 40%

Deep Space (7 presets — ds9 ×2 · nx ×2 · tng ×2 · voyager ×1)

Preset	Era	Elements heard
The Avalon: Interstellar Cruise Concourse	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
The Nightflyer: Telepathic Corridor	ds9	Cardassian Sensor 50% · Single Chirp 50%
USS Ascension: Generation Ship Promenade	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Ark One: Evacuation Ark Bridge	voyager	Double Chirp 60% · Sensor Sweep 40%
Icarus II: Solar Shield Core	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
Event Horizon: Gravity Singularity Core	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Lewis & Clark: Rescue Cutter Bridge	ds9	Cardassian Sensor 50% · Single Chirp 50%

Outlaw (6 presets — ds9 ×1 · nx ×1 · tos ×2 · voyager ×2)

Preset	Era	Elements heard
The Betty: Salvage Freighter Mess	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Bebop: Living Quarters & Hangar	tos	TOS Computer Warble 60% · TOS Relay Click 40%
Outlaw Star: Grappler Bridge	voyager	Double Chirp 60% · Sensor Sweep 40%
Scorpio: Wanderer Salvage Vessel	tos	TOS Computer Warble 60% · TOS Relay Click 40%
The Marauder: Havoc Shuttle Bridge	ds9	Cardassian Sensor 50% · Single Chirp 50%
The Milano: M-Ship Cockpit Lounge	voyager	Double Chirp 60% · Sensor Sweep 40%

Space Stations (6 presets — ds9 ×1 · nx ×2 · tng ×1 · tos ×1 · voyager ×1)

Preset	Era	Elements heard
Babylon 5: Core Control & Zocalo	ds9	Cardassian Sensor 50% · Single Chirp 50%
Moonbase Alpha: Main Mission Control	tos	TOS Computer Warble 60% · TOS Relay Click 40%
Sevastopol Station: Habitation Deck	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Tycho Station: Asteroid Construction Bay	voyager	Double Chirp 60% · Sensor Sweep 40%
Ceres Station: Sub-Crustal Tunnels	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Gateway Station: Quarantine Transfer Deck	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%

Comedy (5 presets — nx ×1 · tng ×2 · tos ×1 · voyager ×1)

Preset	Era	Elements heard
USS Orville: Command Bridge	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
NSEA Protector: Beryllium Engine Room	voyager	Double Chirp 60% · Sensor Sweep 40%
Heart of Gold: Improbability Bridge	tng	Single Chirp 45% · Double Chirp 30% · Ack Sequence 15% · Sensor Sweep 10%
HMS Camden Lock: Flight Deck & Mess	nx	NX Hydraulic Relay 50% · NX Indicator Beep 50%
Spaceball One: Mega-Warship Bridge	tos	TOS Computer Warble 60% · TOS Relay Click 40%

Notes on the spread

• Starfleet is the only universe where the era always matches the fiction.
• Whoniverse spans all five eras across its seven presets — the widest spread of any universe, and the most likely place to hear something unexpected.
• Retrofuture leans on tos (3 of 8), which is at least era-plausible for mid-century-styled ships, but Discovery One and The Searcher are on full TNG LCARS.
• Bioships has no acoustic relationship to any Trek era; Talyn on ds9 produces the Cardassian tritone tone inside a living-ship profile.
• Comedy and Spaceball One on tos produce the analog warble.

Two consequences worth keeping in mind when editing:

1. Changing a preset's telemetry.era silently changes which sounds it makes. There is no UI anywhere that names the active era, so the change is audible but not visible.
2. Any era value outside the five above falls through the switch in playRandomTelemetrySound() to the tng default. A typo does not fail loudly — it just produces LCARS chirps.

If a universe should stop borrowing Trek telemetry, the fix is a new era vocabulary (new elements plus a new case in the era router), not a change to these preset assignments alone — the router has nothing else to offer them.