Technology
Passive RF Sensing
Radio-frequency activity as evidence: timed, qualified, never treated as identity.
What it observes
It listens to radio-frequency activity that is already in the environment and records when, in which class of band and with which characteristics each emission was heard. What it observes is a signal, not an object.
The principle
A public-safe diagram of the mechanism, drawn without real values.
The diagram shows an abstract band with no values: emissions appear as marks on a shared time line, each qualified by how it was received. Nothing in the figure names a frequency or a place.
Where it sits in the chain
It sits at the first band of the pipeline, where the physical world becomes observations. Its output goes to time alignment before anything else uses it, and it never skips that step.
What it does to the data
A received emission becomes a timed, qualified observation with its source and its conditions attached. It becomes evidence for a later step, never a statement of identity.
How it shows up in the data
- Source A
- Source B
- Source C
| Item | Source A | Source B | Source C |
|---|---|---|---|
| Agreement | 82 | 58 | 70 |
| Freshness | 64 | 88 | 52 |
| Completeness | 90 | 70 | 60 |
Strengths / Constraints
Strengths
- It adds evidence where no other source is looking, including beyond the view of any one camera.
- It is passive: it needs no emission of its own and does not announce itself.
- Its observations are timed, so they can be set beside other sources on one clock.
Constraints
- It hears emissions only; an object that does not emit leaves nothing to hear.
- A heard emission says that something transmitted, not what it was or who sent it.
- Its value depends on where the node stands and on what the surroundings do to the signal.
Environmental dependencies
Buildings, terrain, weather and the local radio environment change what a node can hear. The page therefore states conditions with each observation and gives no range.
Limitations
- Source availability: the node can only hear what is emitted, so the absence of a signal is not the absence of an object.
- Line of sight and surroundings: reception changes with terrain, buildings and distance, so coverage differs from site to site.
- Confidence variability: the same emission can be heard well at one moment and poorly at the next, and confidence moves with it.
- Validation scope: the technology is described as a design at the evidence level of its projects; no field range or accuracy is stated.
Evidence and validation
This page claims nothing above the level of the projects it rests on.
- Passive RF Sensing NodeEvidence level: E1 · Architecture Defined
- Drone Detection & Airspace Intrusion IntelligenceEvidence level: E0 · Concept