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Technology

Time Alignment & Data Quality

Badly aligned data can tell a confident, wrong story.

See Data Quality in the Architecture

What it observes

It does not observe the sky. It observes the observations: when each one was made, by which clock, and how far it can be trusted. Without it, sources cannot be set side by side.

The principle

A public-safe diagram of the mechanism, drawn without real values.

The diagram shows several sources on one time line, each with its own offset, brought to a shared clock; a band around each mark shows how far it can be trusted. The figure is a replay, not a live feed.

Conceptual timing band: Data table
ItemValue
Timing bandField
Conceptual timing band RD02Data status: IllustrativeEvidence level: E0 · ConceptQuestion answered: How does sensing unfold over timeA fixed arc band fades in twice across a field and then stays still. It illustrates sensing over time in general terms and never turns or follows an object.Limitation: A general illustration of timing. It does not depict passive coherent location or any real sensor.

Where it sits in the chain

It is the second band, between the observations and everything that uses them. Correlation, fusion and tracking all start from data that has passed through here.

See the architecture

What it does to the data

Observations arrive with their own clocks and their own faults. They leave with a common time, a freshness, a completeness and a statement of what is wrong with them.

How it shows up in the data

  • Normal
  • Degraded
  • Unavailable
System health over time: Data table
Time (relative)Component 1Component 2Component 3
1NormalNormalNormal
2NormalNormalNormal
3NormalNormalNormal
4NormalNormalUnavailable
5NormalNormalUnavailable
6NormalDegradedNormal
7NormalDegradedNormal
8DegradedNormalNormal
9DegradedNormalDegraded
10NormalNormalNormal
11NormalNormalNormal
12NormalNormalNormal
System health over time CH07Data status: Synthetic dataEvidence level: E0 · ConceptQuestion answered: How has system health changed?Three bands, one for each of three example components, show normal, degraded and unavailable periods as different fills and patterns, so state never depends on colour alone.Limitation: Periods are invented and say nothing about any real component.

Strengths / Constraints

Strengths

  • It makes it possible at all to compare sources that disagree about the time.
  • It makes data quality visible, so a weak observation is shown as weak.
  • It keeps the original time next to the aligned one, so the correction can be checked.

Constraints

  • It can correct only what it can measure; an unknown clock error stays unknown.
  • A well aligned observation is not a true observation; it is a comparable one.
  • It adds a step, and every step adds a delay that must be stated.

Environmental dependencies

Network delay, clock drift, loss of a reference and the state of each source change the quality of alignment. The page states these as conditions and gives no accuracy.

Limitations

  • Source availability: a source that stops sending leaves a gap, and the gap is recorded as a gap.
  • Environment: the conditions of the network and the clocks change from hour to hour.
  • Confidence variability: alignment quality differs between sources and over time, and the confidence of what follows moves with it.
  • Validation scope and integration dependency: the technology is a design at the evidence level of its projects, and everything downstream depends on it; no accuracy or delay is stated.

Evidence and validation

This page claims nothing above the level of the projects it rests on.

Projects behind this