Track-While-ScanTrack-While-Scan(TWS)(TWS)

Naval Weapons SystemsNaval Weapons Systems

Learning ObjectivesLearning Objectives

Comprehend concepts of TWS Comprehend concepts of TWS systemsystem

Know the six basic functions of a Know the six basic functions of a TWS systemTWS system

Comprehend the concepts of Comprehend the concepts of acquisition, tracking, and turning acquisition, tracking, and turning gatesgates

Limitation of Traditional Limitation of Traditional Search Radar:Search Radar:

NO FIRE CONTROL NO FIRE CONTROL SOLUTIONSOLUTION

ProblemsProblems Dedicated FC radar can only track Dedicated FC radar can only track

one target.one target. Systems usually have separate Systems usually have separate

Scanning and Tracking Radars.Scanning and Tracking Radars. The target knows it’s being The target knows it’s being

tracked.tracked. The target can initiate Counter The target can initiate Counter

MeasuresMeasures Weapons home in on FC radarWeapons home in on FC radar

Concept of TWSConcept of TWS

Maintain Target tracks in a Maintain Target tracks in a computercomputer

Periodic updates from a Periodic updates from a scanning radar scanning radar

Functions of TWSFunctions of TWS DetectionDetection CorrelationCorrelation Track Initiation and file generation (if Track Initiation and file generation (if

a new target)a new target) Tracking “Gates”Tracking “Gates” Gate prediction, smoothing and Gate prediction, smoothing and

positioningpositioning Predict future target positionPredict future target position

Gate GenerationGate Generation

Acquisition gateAcquisition gate

Tracking gateTracking gate

Turning gateTurning gate

Acquisition GateAcquisition Gate

10 degrees

10 degrees

2000 yards

Tracking GateTracking Gate

1.5 degrees

1.5 degrees

120 yards

Turn Detection GateTurn Detection Gate

*Computer determines size of gate

tracking gate

TWS ProcessingTWS Processing

Acquisition Gate

Tracking Gates

Turn Detection Gate

Tracking Gates

Original Course

Track Initiation and Track File GenerationTrack Initiation and Track File Generation

Track fileTrack file• Store position and gate dataStore position and gate data

Code for acquisition windowCode for acquisition window Calculations on the Calculations on the returnreturn of a of a

target are done by a computer.target are done by a computer.• Much too slow to maintain a small Much too slow to maintain a small

tracking gate.tracking gate.

Positioning and Smoothing Positioning and Smoothing FunctionsFunctions

Repositioning and smoothing must Repositioning and smoothing must be done within the TWS algorithm.be done within the TWS algorithm.

““Lagging” TargetLagging” Target ““Leading” TargetLeading” Target

• This is done mathematically.This is done mathematically.

TWS DiagramTWS DiagramScanning radardetects a target

Do parameters matchthose from previous scan

NO

Yes Doestrack ambiguity exist

NO

Yes

Generate a new track file & store data

Generate anacquisition gate

Resolveambiguity

Targetpreviously in track or acquisition

Compute target tracking parameters

Acquisition

Track

Generate Track Gate & indicator in file

Update trackingparameters

Reposition trackgate centered onfuture position

Ready for the next radar scan information

Recompute track gate

TWS Radar System AdvantagesTWS Radar System Advantages Scan and Track on same systemScan and Track on same system Tracking information used for Tracking information used for

computation of a fire control solution. computation of a fire control solution.

Immediate Fire Control SolutionImmediate Fire Control Solution

Real World ApplicationsReal World Applications• AN/SYS-2 IADTAN/SYS-2 IADT

used on some missile shipsused on some missile ships

• Mk 92 CAS - FFGMk 92 CAS - FFG• AN/SPQ-9 – 5” GunAN/SPQ-9 – 5” Gun• Mk 23 TAS – NATO Sea SparrowMk 23 TAS – NATO Sea Sparrow• AEGIS C&D AEGIS C&D

holds track files for AEGISholds track files for AEGIS dedicated computer dedicated computer

SummarySummary

Radar continues scanningRadar continues scanning Computer predicts positionsComputer predicts positions Track while Scan!Track while Scan! Track information used for fire Track information used for fire

control solution.control solution.

Questions?Questions?