Seeker/Sensor Technology Assessment for ECAP - PowerPoint PPT Presentation

Presented by Tim Carroll

Session 2 - Carroll

Seeker/Sensor Technology AssessmsntHuntsville, Alabama January 16, 2004

Tim Carroll

AMCOM

tjcarroll@knology.net

Session 2 - Carroll

Outline

• Definitions
• Background Information
• Seeker Types
• Radar Seekers
• Electro-Optical Seekers
• Laser Seekers

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• Definition - The seeker is the eye of a missile. Its job is to acquire and track the target until the missile impacts the target. The seeker provides bore-sight error signals (position of the target relative to the center axis of the missile) to the guidance algorithms. This energy is usually electromagnetic (EM) but can be other forms of energy as well (i.e., acoustic).
• Seeker Block Diagram

Target

To

Guidance

Computer

Electrical Processor

Gimbal

Platform

Receiver/Detector

Aperture

(Antenna or Optics)

Transmitter

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• Field-of-View – The angular area in space at which the seeker can observe at any given time (the FoV for radar seekers if referred to as ‘Beam Width’).
• Field-of-Regard – The total angular area that a seeker can view by slewing the seeker aperture up and down and left to right on gimbals. Some missile seekers have no slewing mechanism and are called strap-down seekers (then the FoV and FoR are the equal).

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Operational Engagement Requirements

Engagement Time Lines

Coverage Area

Aerodynamics

Nose Shape

Guidance Scheme

Seeker Type (Active or Passive)

System Simulation

FoV

Detection Range

Size Constraints

Diameter

Length

Seeker/Sensor

Design

Mechanical Design

and Layout

Size

Weight

Target Type

Wavelength

Power Requirements

Cost Constraints

Strap-Down vs. Gimballed

Multi-Mode

Electrical System

Power Requirements

Voltage

Current

Logistics Considerations

Packaging and Handling

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• An electromagnetic disturbance that is composed of time-varying electric and magnetic fields and can transport energy through space, even if no matter is present in that space, is called an electromagnetic wave (abbreviated EM).
• EM waves propagate at the speed of light.
• The electric and magnetic waves in an EM wave are oriented at 90 degrees to each other and to the direction of propagation.
• EM waves travel in straight lines.
• Objects in temperature above absolute zero emit EM waves in the Infrared (IR) spectrum.

Direction of Propagation

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• EM frequencies and wavelengths are related by the following expression:

where l = wavelength, c = speed of light (3x108 meters/sec),

and f = frequency of oscillation.

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• Seekers are catagorized by which spectral band of EM radiation they operate within
• Microwave
• MMW
• E-O (Visual and IR)
• Laser (CO2 – 10.6mm, YAG – 1.06mm, GaAs – 0.9mm)

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• Active seekers transmit energy and the receive the reflected energy. Examples are Microwave Radars, Millimeter Wave Radars, and Laser Radars (LADAR).
• Passive seekers look for natural occurring EM radiation (Infrared) or reflected EM radiation (Visual).
• Semi-Active Seekers operate in one of two modes:
• Other asset illuminates target while missile seeker operates in a passive mode to detect reflect EM radiation.
• Missile is guided to target by other asset and then the missile seeker becomes active near the target. This is also called “Terminal Active”

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• Stabilized Seeker Head
• Seeker Head is isolated from the missile body motion through gimbals, servo motors, and rate sensors. A clear stabilized image/signal is presented to the seeker detectors.
• Increase cost,complexity, size and weight
• Strap-Down Seeker
• Seeker is rigidly attached to the missile body and observes the same motion as the missile
• Cheaper, lower quality image/signal, smaller Field of Regard
• Limited engagement geometries

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Advantages

• All Weather
• Range and Range Rate Information
• Long Operating Ranges
• Low degradation due to battlefield obsurants
• Doppler detection for moving targets
• Low drag nose shapes

Disadvantages

• Large Components
• Large Aperature
• Active Mode
• Large Angular Resolution
• High Cost

State of the Art

• Phased Array Radars
• Doppler Beam Sharpening
• Synthetic Aperture Radar
• Radiometric
• Multisensor/Sensor Fusion

Microwave Radars are best suited for large missiles or ground based systems

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Advantages

• All Weather with some degradation
• Range and Range Rate Information
• Small Components
• Small Angular Resolution
• Doppler detection for moving targets
• Low drag nose shapes

Disadvantages

• Active Mode
• High Cost
• Relatively Short Operating Ranges

State of the Art

• Small Components
• Doppler Beam Sharpening
• Strapdown Configurations
• Radiometric
• Multisensor/Sensor Fusion

MMW Wave Radars are suited well for small missiles and short detection ranges

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Advantages

• Small Components
• Small Aperture
• Very Small Angular Resolution
• Passive Mode
• Small Miss Distances
• Aim-point Bias Capability

Disadvantages

• Weather Degradation - Moderate
• Battlefield Obscurant Degradation - Moderate
• No Range or Range Rate Information
• High Cost
• High Drag Nose Shapes Required

State of the Art

• Focal Plane Array
• Uncooled IR Sensors
• Strapdown Configurations
• Multisensor/Sensor Fusion

IR Seekers are suited well for small missiles and short detection ranges that require precise hit locations

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Advantages

• Small Components
• Small Aperture
• Very Small Angular Resolution
• Passive Mode
• Small Miss Distances
• Aim-point Bias Capability

Disadvantages

• Weather Degradation - High
• Battlefield Obscurant Degradation - High
• No Range or Range Rate Information
• High Cost
• High Drag Nose Shapes Required
• Cannot Operate at Night

State of the Art

• Strapdown Configurations
• Multisensor/Sensor Fusion

Visual Seekers are not in use much anymore due to the lack of night vision and lack of capability in obscured environments

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Advantages

• Small Components
• Small Aperture
• Range and Range Rate Information
• Small Miss Distances
• Aim-point Bias Capability

Disadvantages

• Weather Degradation - High
• Battlefield Obscurant Degradation - High
• Dependency on Designator (Semi-Active)
• High Cost
• No Fire-and-Forget Capability
• Small Search Areas

State of the Art

• LADAR
• Side-Looking Beamriders
• Multisensor/Sensor Fusion

Laser Seekers are used in semi-active missiles where designating assets are available

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Snapshot from MS Excel utility used in

Seeker/Sensor Design.

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