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Domain Glossary

Maritime tactical analysis terminology for Future Debrief. This glossary defines the domain concepts used throughout the codebase and documentation.

Note: Adapted from the legacy Debrief glossary, focusing on domain concepts rather than implementation details.

Core Concepts

Fix

A single timestamped position report containing:

  • Time — when the observation was made (microsecond precision)
  • Location — geographic coordinates (latitude, longitude, depth)
  • Course — direction of travel
  • Speed — rate of movement

Fixes are the atomic unit of positional data in Debrief.

Track

The complete historical movement record of a vessel, composed of sequential fixes. A track includes:

  • Ordered collection of fixes
  • Display attributes (color, symbol, label)
  • Associated sensors
  • TMA solutions (if applicable)

Track Segment

A logical grouping of consecutive fixes within a track. Segments allow tracks to be subdivided for analysis or to represent different data sources/qualities. Common segment types include:

  • Core segment — observed positional data
  • TMA segment — reconstructed target motion from sensor observations
  • Planning segment — projected future movement
  • Infill segment — interpolated positions between known fixes

Sensor

A shipboard observation device (sonar, radar, visual) that generates observations of other vessels. Sensors maintain:

  • Collections of contacts/cuts
  • Display properties
  • Sensor-specific parameters (e.g., frequency for acoustic sensors)

Contact (Cut)

A single measurement from an ownship sensor—typically bearing and/or range to a target vessel. A contact contains:

  • Timestamp — when the observation was made
  • Bearing — direction to target (may include ambiguous bearing)
  • Range — distance to target (if available)
  • Frequency — acoustic frequency data (for sonar)

The term "cut" is often used interchangeably with "contact" in TMA analysis.

Bearing

The direction from one point to another, measured as an angle from north. Types include:

  • True bearing — measured from true north
  • Relative bearing — measured from ownship heading
  • Ambiguous bearing — passive sonar's 180° alternate solution (sonar cannot distinguish which side a contact is on)

Plot

A collection of tracks and associated data representing a tactical scenario or exercise. In Future Debrief, plots are stored as STAC Items with GeoJSON payloads.

Target Motion Analysis (TMA)

TMA

Target Motion Analysis — the analytical process of estimating a target vessel's course and speed based on ownship sensor observations (typically bearing-only from passive sonar).

TMA relies on ownship maneuvers to resolve ambiguity: by changing ownship course/speed across multiple legs, the geometry changes enough to triangulate target motion.

Leg

A period of time during which certain conditions remain consistent. Types include:

  • Ownship leg — period of steady ownship course and speed
  • Bearing leg — period of consistent bearing rate (requires minimum observations for valid TMA)

Leg boundaries are significant for TMA because each leg provides different geometric perspectives on the target.

SATC (Semi-Automatic Track Construction)

An automated process for generating TMA solutions from sensor observation data. SATC uses optimization algorithms to transform:

  • Ownship positions over time
  • Bearing observations to target

Into a reconstructed target track with estimated course and speed.

Planning Segment

A projected vessel route defined by intended (rather than observed) parameters:

  • Course — intended direction
  • Speed — intended rate of travel
  • Distance or Duration — extent of the segment

Planning segments support "what-if" analysis and mission planning.

Data Types

World Location

A 3D geographic position:

  • Latitude — -90° (South) to +90° (North)
  • Longitude — -180° (West) to +180° (East)
  • Depth — positive values indicate underwater depth; negative values indicate altitude

World Speed

Speed with support for multiple units:

  • Knots (nautical miles per hour)
  • Metres per second
  • Kilometres per hour
  • Feet per second

World Distance

Distance with support for multiple units:

  • Nautical miles
  • Metres / kilometres
  • Yards / feet

World Vector

A combination of bearing and distance representing direction and magnitude from one point to another.

High-Resolution Date

A timestamp with microsecond precision, essential for:

  • Timeline synchronization across multiple tracks
  • Precise fix ordering
  • Temporal queries and filtering

Coordinate Conventions

Bearing Reference

Direction Degrees Radians
North 0° 0
East 90° π/2
South 180° π
West 270° 3π/2

Geographic Coordinates

  • Latitude: Positive = North, Negative = South
  • Longitude: Positive = East, Negative = West
  • Depth: Positive = below surface, Negative = above surface

Historical Context

Debrief's design reflects its origins in submarine tactical analysis:

  • Bearing-only TMA assumes known ownship position with unknown target position, observable only through passive sonar bearing (and sometimes frequency). This predates widespread GPS availability.

  • Yards and radians as internal units reflect historical naval conventions, though modern interfaces typically display knots, nautical miles, and degrees.

  • Ambiguous bearings exist because passive sonar cannot determine which side of the array a sound originates from, producing two possible bearings 180° apart.

See Also