RADAR TRACKING SYSTEMS Radar Tracking Systems Objectives Describe

RADAR TRACKING SYSTEMS

Radar Tracking Systems

Objectives • Describe how a radar servo tracking system keeps the antenna pointed at the target. • Distinguish between single beam, dual beam and monopulse tracking system and identify which system is accurate enough for use in a fire control system. • List and explain the 6 functions of the TWS system • Outline how the 3 tracking gates used by the TWS system generate position information for a target from initial acquisition through a turn.

The “Problem” • Locating, Tracking and Engaging faster, more maneuverable targets from platforms that roll, pitch and yaw (рыскать)! • Limitation of sensor capabilities – Search Radar – Fire Control (FC) Radar

FC Radar Servo Tracking Systems • Motor – physically rotates antenna. – Electro-hydraulic motor for large systems. – Electric motors for smaller systems. • Servo-mechanism – controls direction of antenna rotation. – Receives two inputs: • Tracker – azimuth to point at. • Antenna position sensor – where antenna is pointed.

FC Radar Servo Tracking Systems • Tracker – determines target azimuth and antenna position error (magnitude and direction). – Single beam system. – Dual beam system. – Monopulse. • Gyro – Provides a stable reference for system. – Negates roll, pitch and yaw. – Data smoothing.

Servomechanism Tracker Output Order to Motor Controller Position Sensor Servo Move Antenna

Tracking – Single Beam Target location at the point of max return. Insufficient accuracy for weapons delivery

Conical Scan

Tracking – Dual Beam Ideally, target centered between two beams. • Improved accuracy over single beam system • Sufficient accuracy for weapons delivery.

Tracking - Monopulse • Essentially 2 Dual beam systems • One Azimuth • One Elevation • High accuracy • Used for fire control tracking.

Range Tracking/Gates • Merge of Dual Beam FC tracking system with a integration computer. – Provides continuous info as to target’s “predicted” position. • Early gate. • Late gate. • Based upon abilities of FC technician, can Range Track more than one target.

Fire Control Radar Tracking Problems • Fire Control tracking always “lagged” Fire Control problem. • Target possibly knows it’s being tracked by a fire control radar. – Hence commence evasive maneuvers

Solution Track – While – Scan (TWS)

Concept of TWS • Incorporate a search radar and a computer. • Radar continues to perform primary functions of search (scanning) and determines target position. • Radar sends position data to the tracking computer. • Computer performs target tracking calculations on all target data provided. • System is able to accurately predict target position. Track While Scan (TWS) – LEAD the Target!

Fundamentals of TWS Six Basic Functions: • • • Target detection Track initiation and track file generation Generation of tracking “Gates” Target track correlation Track gate prediction Display

Target Detection • Automatic Detection and Tracking (ADT). – Digitizes (0’s and 1’s) scan area of search radar. – Each position in search area given specific digital “address”. – Once radar return received by ADT, FC solution generated for specific “address”.

Track Initiation and Track File Generation • Track file generated to store position (address) and gate data for each track. • Generation begins with initial storage of position (address) data. – – – Lat / Long. Course / Speed. Bearing / Range /Altitude. Estimated Position (EP) data. Correlating data (from own ship).

Gate Generation • Acquisition Gate (Largest) • Tracking Gate (Smallest) • Turning Gate Predicted Position Measured Position Tracking Gate Turning Gate

TWS Gates Acquisition Gate 10 degrees 2000 yards

TWS Gates Tracking Gate 1. 5 degrees 120 yards

TWS Gates Turn Detection Gate Tracking Gate *Dimensions of this gate are determined by computer based on speed of target.

TWS Processing Original Course Reacquire Target Turn Gate Tracking Gates Resume Tracking Acquisition Gate

Track Correlation • System Resolution Rules. – Software decisions based upon threat environment and ROE. – Ambiguities resolved for: • Multiple gates on same target. • Multiple targets in same gate. • Crossing targets. • Computer has algorithms to sort out conflicts (e. g. , contacts swapping identification during merge) • Operator must check computer results

TWS Radar System Advantages • • • Automated tracking Track prediction Tracks multiple targets simultaneously Tracking info used to compute FC solution Tracks with only a search radar and a computer

Real World Applications – AN/SYS-2 IADT (Integrated Automated Detection and Tracking) • Carriers • CG • DDG • FFG

Tracking Recap • Servo tracking systems can only handle a few, maybe just one, track(s) • Likely lag the problem (fire solution slow/inaccurate) • Wait for an update (radar hit) to re-position antenna and target plot • Track While Scan systems can easily handle multiple targets • Keep targets within predicted volume in space • System is projecting ahead to where the target should be next