HSH-1001 - Ephemeral Telemetry and Phosphor Decay

Living Document Notice
Published 2026-09-09. The evolving architecture, revisions, and connected notes for this dispatch live in the Stax Digital Garden.

Ephemeral Telemetry and Phosphor Decay

Summary

Modern monitoring tools accumulate telemetry records indefinitely. Time-series databases store every radio packet, ping response, and contact coordinate into append-only tables, consuming gigabytes of disk storage for signals whose operational utility expires seconds after transmission. For passive ambient monitoring—such as tracking local radio contacts, transponder bursts, and sensor beacons on a dedicated sidecar display—historical persistence introduces unnecessary maintenance overhead and distraction.

Hushwire takes the opposite approach. Built as an ephemeral monitoring console within the Bosun PKM Tools ecosystem, the system processes unbuffered radio packets in memory, renders active contacts across simulated CRT phosphor display planes, and discards all records the instant their visual decay curve terminates. By enforcing a zero-retention storage invariant, the monitoring terminal delivers continuous situational awareness while maintaining a static memory footprint.

Unbuffered Packet Ingestion

High-frequency telemetry interfaces typically ingest raw frames from software-defined radios (SDR), local serial buses, or network demodulators. When tracking Mode-S or ADS-B frames via standard dump1090 feeds, packet arrival rates fluctuate between 50 and 800 messages per second depending on local antenna line-of-sight.

Queueing these packets into disk-backed spool directories creates write amplification and latency jitter that compromises real-time display updates. Hushwire avoids queuing entirely by mounting a non-blocking UDP loopback listener paired with a fixed-length memory ring:

[SDR Demodulator] -> UDP Loopback -> Non-Blocking Socket -> Fixed-Ring Allocator -> Canvas Blit
                                                                 │
                                                                 ▼
                                                    (Drop on Buffer Saturation)

If incoming packet velocity exceeds the parsing loop budget, surplus frames are dropped immediately at the socket boundary. Radio signals represent real-time physical states; stale frames delayed by even 500 milliseconds carry zero operational value for active positional tracking.

Simulated Phosphor Decay

On physical cathode-ray tubes (CRTs) utilizing long-persistence phosphors such as P7 (copper-activated zinc sulfide), a radar sweep leaves an immediate bright blue fluorescence followed by an extended yellow-green phosphorescence that decays over several seconds. This physical decay allows human operators to infer velocity vectors and contact heading without software calculation.

Hushwire reproduces this visual retention mathematically inside a 2D HTML Canvas render loop. Rather than retaining historical coordinates in relational arrays, each coordinate contact registers an initial intensity value ($I_0=1.0$) upon packet arrival. A tick worker decrements intensity values according to an exponential decay function:

// State decay per render cycle
function stepPhosphorDecay(contacts, deltaSeconds, halfLifeSeconds) {
  const decayFactor = Math.exp(-deltaSeconds * (Math.LN2 / halfLifeSeconds));
  for (let i = contacts.length - 1; i >= 0; i--) {
    contacts[i].intensity *= decayFactor;
    if (contacts[i].intensity < 0.02) {
      // In-place swap-and-pop eviction from fixed array
      const last = contacts.pop();
      if (i < contacts.length) {
        contacts[i] = last;
      }
    }
  }
}

Eviction occurs strictly when intensity falls below the visible threshold ($I<0.02$). Once evicted from the active array, coordinate objects are released to the runtime garbage collector, ensuring that contact density directly dictates memory utilization rather than session uptime.

Zero-Retention Logging Invariants

Unlike ingestion relays in the Tender daemon that spool file modifications for durable note synchronization, Hushwire explicitly isolates volatile radio telemetry from the persistent filesystem:

1. No SQLite Intermediate: Telemetry records bypass local relational databases. Positional states live only in typed array buffers.
2. No Append-Only Outboxes: Network disconnects clear the display canvas rather than backpressuring disk spools.
3. No Origin Coordinates: The terminal tracks contacts relative to receiver distance without persisting base station coordinates to disk config files.

When operators close the browser tab or terminate the monitoring container, the entire telemetry state vanishes without leaving residual cache files.

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• Directus Target: hushwire
• Garden Source Reference: MOC - Hushwire, MOC - Ingestion & Capture, MOC - Bosun PKM Tools