Airborne Imaging Line Scanner Modernization

Patrick O’BrienMatthew Weinstock

Design Overview

Modernizing a Vietnam War era scanner used to obtain visible and infrared images from low speed aircraft (converted from high speed aircraft (F-4 Phantom ‘Wild Weasel’) ran scanner from an aircraft speed near Mach 1 and obtained infrared images only)

Airborne Line Scanner

Airborne Line Scanner

Two sets of mirrors: flat and curved Four flat mirrors rotated by variable

controlled DC motor One stationary curved mirror and one

stationary flat mirror

Rotating flat mirrors obtain one dimension of the image, while aircraft’s forward motion provides the second dimension

Airborne Line Scanner Diagram

Operation of Scanner

Photodiode

Used as Spectrometer in Scanner

Photodiode

DC Motor

Variable Controlled from DC sourceMaximum of 10 HzAbsolute shaft encoder used to determine position of motor (rotating mirrors)Enclosed in scanner chassis

PCB123 and Front End Analog

Company used to design and produce PCB boards used in projectDesign program from PCB123 similar to that of P-Spice combined with VLSI design

Front End Analog Schematic

Absolute Shaft Encoder

Precision guaranteed because every position is definableAble to obtain current position without needing a reference pointAttached to scanner chassis through bracket

Analog to Digital Converter

Portable USB-Based DAQ with Simultaneous Sampling (Windows) produced by National InstrumentsFIFO technology System made for continuous data

acquisition Data held in continuous memory

Needs to have 12-bit resolution, will have at most 16 bits of digital I/O

Analog to Digital Converter

Sampling rate of A/D is at most 60,000 samples/second Sample rate = mirror speed * number

of samples per revolution Maximum mirror speed is 10 Hz Number of samples is 6,000

A/D includes software drivers that will be customized for scanner

Controlling Unit

‘Briefcase Computer’ with AMD/Intel technologyCPU will run ActiveX controls and Visual Basic Code which will control data input and motor control

ActiveX and the A/D

‘Click and Drag’ programming abilityWide variety of controlsInterfaces with most technologies Will be used to interface A/D with the

‘Briefcase Computer’

Visual Basic Software and The Motor

Visual Basic offers ease of design for GUIProcesses will be triggered by movement and clicking of slider and buttonsGUI will also relay information gathered from motor and encoder

User Interface

User Interface: Start and stop system Controls how many times the flat

mirrors will turn Controls the speed of the motor Will show a preview of the image

captured, a numeric value for mirror speed, and the sensor temperature

User Interface

Questions