CALIBRATED PRESSURE · ENCRYPTED HOME SIGNAL

Pressure
Canary

Calibrate to the air inside a secured building, phone home continuously, and go silent when a broken window or opened door crosses that building’s validated pressure signature.

The defining output is absence: the envelope changes, the canary trips, and the continual encrypted signal stops.

An opening changes the room pressure; the pulse chain ends at the trip, leaving the home receiver in silence.

THE SECURITY PROBLEM

The remote-boundary problem

Remote workshops, seasonal houses, storage rooms, and vacant buildings often accumulate separate door contacts, cameras, motion alerts, power monitors, and network checks. Each reports one component, and each can fail noisily enough that the owner learns to ignore it. What the owner actually needs to know is simpler: has the secured envelope remained undisturbed, and is the device capable of saying so?

The ordinary bad night: wind and insects generate motion alerts until they are muted. Later a window is opened during a power or communications failure, and the absence of a useful alarm looks exactly like another quiet night.

With Pressure Canary: a sensor calibrated to the building’s internal air pressure continually sends an encrypted signal home while the envelope holds. Where testing demonstrates a separable signature, a door or broken window trips the pressure condition and stops the signal; destruction, lost power, or a severed link also produces the one condition the receiver cannot treat as normal—silence.

CALIBRATE / CALL / CUT OFF

Local sensing sequence

Learn the room

Calibration establishes the internal pressure reference for the secured envelope.

Phone home

The armed unit continually transmits an encrypted signal to its designated home receiver.

Canary-trip

A broken window or opened door creates a candidate pressure event; when it crosses the building’s validated signature, the device immediately stops phoning home.

THE MESSAGE IS SILENCE

Heartbeat failure semantics

The canary does not need to describe the opening in a long report. Its contract is binary and continual: while the calibrated envelope holds, the encrypted home signal persists. When the pressure trip occurs, transmission ceases.

SENSOR: Measures the calibrated internal pressure and watches for the trip condition.
CIPHER: Protects the continuous home signal so a copied plain heartbeat cannot simply be replayed.
HOME: Expects the signal on schedule and recognizes the interruption immediately.
ALARM: Treats the missing canary as evidence that a door, window, device, power path, or link must be checked.

WHAT CALIBRATION MUST SEPARATE

False-positive controls

A controlled operating-room study showed that one internal barometric sensor could detect door-opening pressure drops in a positively pressurized room. Houses and workshops are not operating rooms: leakage, wind, stack effect, HVAC state, room volume, and opening geometry can weaken, erase, or imitate that signature.

WeatherOutdoor pressure drift and gusts must not consume the internal reference or impersonate a breach.
HVACFans, dampers, ventilation cycles, and equipment starts must remain distinguishable from the local trip signature.
Door openingAn opening is an intended candidate event only where field calibration demonstrates a repeatable separation from noise.
Broken windowA sacrificial-panel trial must show whether that building actually produces a recognizable breach signature.
Lost deviceDestruction, power loss, or severed communication also ends the expected home signal.

NARROW DATA

Signal architecture

The concept does not require household audio, video, or a detailed occupancy diary. Its essential remote fact is that the calibrated device is still phoning home. The critical security properties are encrypted continuity, a dependable deadline, and an alarm that cannot mistake silence for normal operation.

THE DECISIVE FIELD TEST

Validation boundary

Test leaky and tight rooms across seasons, wind directions, HVAC states, interior and exterior doors, and sacrificial window panels. The calibrated unit must reject ordinary pressure noise, catch the repeatable breach event, and stop its encrypted transmission immediately. Buildings that do not produce a separable signature fail deployment rather than receiving a confident but imaginary threshold.