The GER EPS-H Airborne Imaging Spectrometer incorporates GER's proprietary technology, and is based on GER's extensive experience in application definition and analysis, system design and fabrication and system deployment mission management. The EPS H represents the high end of GER's system lines. With a large collection aperture and an ability to incorporate multiple spectrometer units, this system can be customized to meet virtually any set of application requirements using GER's modular design elements.
GER is unique among hardware suppliers for remote sensing in that it not only designs and builds airborne systems and portable field spectrometers, it also operates the systems in its own aircraft. GER's many years of successful survey experience worldwide are not only founded on GER's state of the art systems, but also rely on GER's providing complete data processing and interpretation services. Based on this experience, GER has designed the GER EPS-H as most technically advanced and cost effective solution for a broad range of applications.
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GER EPS-H System Description
Construction
The EPS-H Multi-Spectral Scanning System is based on modular components developed for the GER EPS (Environmental Probe System) and DAIS (Digital Airborne Imaging System) families of airborne imaging spectrometers such as the EPS 2100M, EPS 5100, DAIS 3715, DAIS 7915 and the DAIS 2815.
TheSensor Unit consists of a Scanner Module based on our mid sized Kennedy Scanner and a custom Spectrometer Module configured to meet the specific applications requirements.
EPS-H Scanner System
The Electronics Rack Unit contains the Workstation Module, the Data Acquisition Module, the Controller Module and the Power Distribution Module. The Operator Interface consists of a Display, a Keyboard/Pointing Device, the Recorder Module and optional Auxiliary Video Output. The Aircraft Interface provides a custom Mounting Frame, Power Input and Data Interface connection. The GER EPS-H Software includes Hyperview™ real time control software loaded on the workstation for operation on board the aircraft and GER Preprocessing Software for post mission data preprocessing.
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The Sensor Unit contains the Scanner and the Spectrometer. The Scanner defines the spatial characteristics of the acquired image while the Spectrometer divides the energy from a pixel on the ground into it's spectral components and transforms that energy into an electronic signal.
The Scanner Module is a "whisk broom" strip mapper. The optical scanner is based on the Kennedy Scanner, which consists of a multi-faceted rotating mirror. As the mirror rotates, the field of view changes and data are acquired across the flight track to form a scan line. Scan lines are accumulated along the flight track and a strip map image is produced.
The two optical paths are aligned for co-registration and focus at infinity. The polygonal mirror provides four (4) scan lines per mirror revolution. The mirror is driven directly by a DC Servo motor and includes a high resolution Digital Rotary Encoder for velocity and absolute positioning feedback to the Controller and Data Acquisition Modules.
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The GER EPS-H Spectrometer is composed of four (5) optical paths and one-hundred and thirty-three (133) channels of spectral information. The Field of View of all spectral bands is determined by a single aperture, so unlike other commercial imaging spectrometers, all channels of the GER spectrometer are fully co-registered assuring accurate measurement of spectra within each individual pixel without additional spatial corrections. The spectrometer is coupled to the Kennedy scanner via a selectable aperture (2.5 mr nominal) that determines the instantaneous field of view of the system. A schematic version of an example of an EPS H spectrometer configuration is shown below.
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Black Bodies
Temperature Controlled black bodies are mounted on either side of the Scan Head for real time baseline correction and Thermometric Calibration. A remote temperature sensor monitors and controls the temperature of each black body.
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Gyro Module
A multi-axis solid state gyro system is provided for image geo-correction. Roll correction is applied in real time. Other geocorrection options are available.
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CONTROL AND DISPLAY ELECTRONICS
Control Module
The controller module consists of the scan mirror controller and the black body controllers. The controllers are intelligent control systems that are programmed via the user interface of the Hyperview™ Software and provide real time control. The scan mirror controller uses the encoder feedback to precisely control the motor speed. The black body controllers use feedback from the remote black body temperature sensors to provide stable black body temperatures.
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Power Distribution Module
The power distribution module uses the aircraft 28V DC and generates all required system voltages.
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Recorder Module
The recommended recorder is an Exabyte Mammoth recorder. The recorder is mounted in the Electronics Rack Unit and is powered by DC voltages derived the Power Distribution Module. The Data interface to the recorder is via industry standard high speed SCSI.
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Options
Optional electronics that can be added to the Electronics Rack Unit include, but are not limited to, a dedicated GPS receiver to interface to a GPS antenna, video converters to provide video feeds to auxiliary consoles in NTSC, RGB, etc. formats. The industry standard VME architecture provides great flexibility in fulfilling custom additions to the MSS Scanner System.
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Operator Interface
The Operator Interface consists of a rugged rack mountable color display and a keyboard with integrated pointing device. Power for the display is a dc voltage that is generated from the Power Distribution Module in the Electronics Rack Unit. The Keyboard is a ruggedized Sun compatible keyboard with an integrated track ball. The user interface to the GER EPS-H is software based and is easily accessed using this integrated keyboard and trackball. The convenient window based menus, controls and displays make interaction user friendly even in a harsh aircraft environment.
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HyperView™
GER'S HyperView™ software provides a simple graphical interface for the operation and monitoring of the GER EPS-H Scanning System. System status may be monitored, real-time image data displayed, and system parameters set from a simple menu driven user interface. Running on the embedded SPARC workstation, HyperView™ provides a versatile tool for both data acquisition and monitoring/enforcement applications requiring real-time data display and interpretation. HyperView™ can also be used for mission playback and additional licenses may be purchased for use on ground based stations. GER will provide Hyperview software updates without charge during the warranty period.
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Image Display Functions
Multiple data display windows are provided with the HyperView™ operating system. These windows allow real-time data display, tracking of acquisition coverage, and enhanced display and storage of data in-flight. The Waterfall Display Window provides the operator with a dynamic, continuously updated view of the sensor data stream. Menu controls are provided to permit selection and placement of bands and to configure snapshot and display options.
A Snapshot Window allows the capture and storage of individual frames of data selected from the waterfall display. Snapshots of data may be enhanced for easy interpretation and recorded or delivered to an external device through a serial interface.
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Mechanical Interface
The Sensor Unit is provided with a shock and vibration isolated mounting frame. The electronics rack enclosure and display are standard mountable devices. They mount directly in standard 19-inch racks.
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System Calibration
The system is initially calibrated in GER's Millbrook laboratory. Spectral Calibration and radiometric calibration of all bands is performed using NIST traceable equipment.
GER can provide calibration facility packages which allow periodic maintenance and calibration to be performed at a customer provided facility.
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Manuals
GER will supply the following manuals at the time of training at the Millbrook facility:
Installation Manual Operations Manual Maintenance Manual
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APPENDIX
I. Spectral Specification
Example of EPS-H sensor configuration:
VIS/NIR Region:
(1 Spectrometer)Spectrometer 1: 76 bands, bandwidth 8nm,
starting from 400nm, ending at 1010nm.SWIR Region 1:
(1 Spectrometer)Spectrometer 2: 16 bands, bandwidth 50nm,
starting from 1000nm, ending 1800nm.SWIR 2:
(1 Spectrometer)Spectrometer 3: 32 bands, bandwidth 16nm,
starting from 2000nm, ending at 2500nm.MIR Region:
(1 Spectrometer)Spectrometer 4: 3 bands, bandwidth 0.67nm,
starting from 3.0nm, ending at 5.0nm.TIR Region:
(1 Spectrometer)Spectrometer 5: 6 bands, bandwith 600nm,
starting from 8700nm, ending at 12300nm.
The actual design, number of spectrometers, detector types, and the placements, are typically tailored to meet the users requirements.
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II. General Instrument Specifications:
Collecting aperture 537 cm2 IFOV True Value: 3.3 mRad, 2.2 mRad,
1.1 mRadSwath Angle ± 39 Pixels per Line 512 to 2048 Scan Speed up to 50 Hz Detectors Si, InSb, MCT MTFB 600 hours Environment Internal Subsystems - 10°C to 40°C
Recorder - 10°C to 40°C, R.H. - 10% to 90%
Electronics - 0°C to 50°C
Scan Head - -20°C to 50°C
No Stray EMIRecording Media Exabyte Mammoth tape drive
2 Mb/sec reording speed
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III. Radiometric Specifications:
Radiometric Resolution 16 bits Radiometric Sensitivity
VIS/NIR
SWIR
MIR/TIR
SNR VIS/NIRminimum expected
NER 0.02 0.01
NER 0.01 0.005 mWcem-2sr-1um-1
NET 0.2 0.2
150 300Calibration Accuracy (absolute) 5% Calibration Accuracy (relative) < 2.5% (between bands) In-Flight Calibration MIR/TIR Blackbody Scan Angle Radiance Sensitivity 2%
Ambient and controlled temperature on board blackbodies for in-flight thermal calibration
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IV. Goemetric Specifications:
Spatial Resolution 10m at 3000 m agl. (3.3 mRad) Band-to-Band Registration < 0.1 pixels between bands Geometric Correction 3 axis gyroscopes accurate to less than 1 pixel
Absolute Positioning
General data port accepts GPS data
Optional Applanix Integrated
Interia/GPS positioning system
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For more information Contact GER
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