Final Attachment B - PORD.pdf

Effective Date: July 11, 2022 418-XO-GXIPORD-0117 Responsible Organization: GeoXO Flight Project/Code 418 Version 1.1

To verify the correct version of this document, please contact the GeoXO Series Configuration Management Office.

Geostationary eXtended Observations (GeoXO) Flight Project

Imager (GXI) Performance & Operational Requirements Document

(GXIPORD)

Signature page

Prepared by:

Electronically approved by:

06/01/2022

Jemma Kline Date GeoXO Flight Project, Instrument Systems Engineer NASA GSFC, Code 418

Reviewed by:

Electronically approved by:

07/11/2022

Steven W. Bidwell Date GeoXO Flight Project, Mission Systems Engineer

Electronically approved by: 07/08/2022 Phillip Driggers Date GeoXO Flight Project, Instrument Manager

Approved by:

Monica Todirita electronically approved for:

07/11/2022

Candace C. Carlisle Date GeoXO Flight Project, Project Manager

/GeoXO Flight Project Imager

GXIPORD

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational Requirements Document (PORD) Phase B

Version: 1.1 Printed by: hlhedger Printed on: Friday, August 12, 2022

No filter applied.

No sort applied.

Generated from DOORS 9.7.2.4

Contents

1 1Scope

1.1 1Identification

1.2 1Mission Review

1.3 1Document Overview

1.4 1Requirements Terminology

1.5 2Definitions

1.6 4Requirement Applicability

2 5Applicable Documents

3 6Sensor Requirements

3.1 6Sensor Definition

3.1.1 6GXI Modes

3.1.1.1 6Safe Mode

3.1.1.2 6Normal Operational Mode

3.1.1.3 6Instrument Diagnostic Mode

3.1.1.4 7Outgas Mode

3.1.2 7On-Orbit Operations

3.1.2.1 7Zones of Reduced Data Quality

3.1.2.1.1 7Operational Zone

3.1.2.1.2 7Restricted Zone

3.1.2.2 8Eclipse

3.1.2.3 8Operations After Maneuvers

3.1.2.3.1 8Yaw Flip

3.1.2.3.2 8Stationkeeping

3.1.2.3.3 8Post Storage Activation

3.1.2.4 8Detector Operating Temperatures

3.2 8Sensor Characteristics

3.2.1 8Coverage

3.2.1.1 8Imaging Modes

3.2.1.1.1 8Imaging Mode A

3.2.1.1.2 9Imaging Mode B

3.2.1.1.3 9Full Disk

3.2.1.1.4 9Superregional

3.2.1.1.5 9Mesoscale

Project: GeoXO Flight Project Imager Module: GXIPORD Baseline Version: 1.1

Contents ii

3.2.1.2 9Flexible and Efficient Imaging Pattern

3.2.1.3 10Field of Regard

3.2.1.4 10Simultaneity

3.2.1.5 10Data Timeliness

3.2.1.6 10Data Collection Overlap

3.2.2 10Channel Definitions, NEDT, Dynamic Range

3.2.2.1 10Baseline

3.2.2.2 12System Spectral Response

3.2.2.2.1 12Spectral Response Envelope

3.2.2.2.2 14Within Channel Spectral Response Uniformity

3.2.2.2.3 14Out-of-Band Response

3.2.2.3 14Low Light Visible Channel

3.2.3 14Spatial Resolution and Sampling

3.2.3.1 14System Modulation Transfer Function

3.2.3.2 15Spatial Response Uniformity

3.2.3.3 16Ringing from a Sharp Edge

3.2.4 17Image Navigation and Registration

3.2.4.1 17Star Sensing

3.2.4.2 17INR Performance Requirements

3.2.4.2.1 17Navigation

3.2.4.2.2 17Frame-to-Frame Registration

3.2.4.2.3 17Within Frame Registration

3.2.4.2.4 17Collection-to-Collection Registration

3.2.4.2.5 17Channel-to-Channel Registration

3.2.5 18Radiometric Accuracy and Precision

3.2.5.1 18Calibration and Accuracy for Wavelengths Greater than 3 Microns

3.2.5.1.1 18Full Aperture Calibration

3.2.5.1.2 18Absolute Accuracy

3.2.5.2 18Repeatability

3.2.5.2.1 18Pixel-to-Pixel

3.2.5.2.2 19Collection-to-Collection

3.2.5.2.3 19Channel-to-Channel

3.2.5.2.4 20Image-to-Image

3.2.5.2.5 20Blackbody Calibration-to-Calibration

3.2.5.3 21Coherent Noise

3.2.5.4 21Calibration of Channels Less Than 3 Microns

3.2.5.4.1 21On-Board Calibration

3.2.5.5 22Spatial Uniformity of Data

Contents iii

3.2.5.6 22Crosstalk

3.2.5.6.1 22Channel-to-Channel

3.2.5.6.2 22Within Channel

3.2.5.7 22Blooming

3.2.5.8 23Quantization Step Size

3.2.5.9 23Electronic In-Flight Calibration

3.2.5.10 23Polarization of Channel Less Than 3 Microns

3.2.5.10.1 23Polarization Control

3.2.6 23System Linearity

3.2.7 23Data Compression

3.2.7.1 23Lossless Data Compression

3.2.7.2 24Lossy Compression

4 25Design Requirements

4.1 25Reliability

4.2 25Redundancy

4.2.1 25Redundant Component Selectabiltiy

4.2.2 25Interchangability of Flight Model Units

4.2.3 25Cryocooler Operation

4.3 25Mechanical Requirements

4.3.1 25Design Limit Loads

4.3.2 26Yield Strength

4.3.3 26Ultimate Strength

4.3.4 26Unit Stiffness

4.3.5 27Critical Members Design Values

4.3.6 27Redundant Members Design Values

4.3.7 27Selective Design Values

4.3.8 27Fracture Control

4.3.9 27Mechanisms

4.3.10 28Pressurized Units

4.3.11 29Alignment Reference

4.3.12 29Precision Component Assembly

4.4 29Thermal Requirements

4.4.1 29Mission Allowable Temperatures

4.4.2 29Thermal Gradients

4.4.3 29Non-Operational Temperatures

4.4.4 30Thermal Control Hardware

4.4.5 30Detector Cooling Margin

4.4.6 30Radiator

Contents iv

4.4.7 30Heat Pipe (Two-phase Heat Transfer Device)

4.5 31Power Requirements

4.5.1 31Power Regulators and Supplies

4.5.2 31Fuses

4.5.3 31Covers for test Connectors

4.5.4 31Keyed Connectors

4.6 31Onboard Processors Requirements

4.6.1 31Flight Load Non-Volatile Memory

4.6.2 31Commandable Reinitialization

4.6.3 31Deterministic Power-on Configuration

4.6.4 32Fail-safe Recovery Mode

4.7 32Flight Software Requirements

4.7.1 32Language and Methodology

4.7.2 32Flight Software Upload

4.7.3 32Flexibility and Ease of Software Modification

4.7.4 32Version Identifiers

4.7.5 32Flight Processor Resource Sizing

4.7.6 33Software Event Logging

4.7.7 33Warm Restart

4.7.7.1 33Processor Re-Start

4.7.7.2 34Autonomous Re-Start

4.7.8 34Memory Integrity

4.7.8.1 34Memory Verification

4.7.8.2 34Bit Error Detection and Correction

4.7.9 34Memory Dump

4.7.10 34Telemetry Cadence and Dwell Control

4.7.11 34Long-Duration Test

4.7.12 34Unnecessary and Unreachable Software

5 35Ground Support Equipment and Development

5.1 35Electrical System Test Equipment

5.2 35Flight Software Development Environment

5.3 35Ground Processing Demonstration System

5.4 36FM and GSE Shipping Containers

6 37GXI Simulators

6.1 37GXI Instrument Hardware Simulator (GXI-IHS)

6.2 37GXI Instrument Software Simulator (GXI-ISS)

Contents v

7 39FM Design Verification Requirements

7.1 39Powered-on Operating Time and Trouble-Free Performance Testing

7.2 39Structural and Mechanical Verification Requirements

7.2.1 39Mechanical Test Factors and Duration

7.2.2 41Minimum Workmanship

7.2.3 42Testing in Flight Configuration

7.2.4 42Structural Proof Testing

7.2.5 43Modal Survey Characterization

7.2.6 43Structural Qualification

7.2.7 43Deployment and Articulation Verification

7.2.8 43Life Test

7.2.9 44Mechanical Clearance Verification

7.3 44Electromagnetic Compatibility Verification

7.3.1 44General

7.3.2 44Electrostatic Arc-Discharge Susceptibility

7.3.2.1 44External Surface-to-Surface direct discharge

7.3.2.2 44Deep Dielectric Charging

7.3.2.3 44ESD Characteristics

7.4 45Thermal Test Requirements

7.4.1 45General

7.4.1.1 45Thermal Test Chronology

7.4.1.2 45Pressure

7.4.2 45Thermal Vacuum

7.4.2.1 45Transition Rates

7.4.2.2 45Corona Operation

7.4.2.3 46Hot and Cold Start Demonstrations

7.4.2.4 46Heater Verification

7.4.2.5 46Flight Temperature Sensor Verification

7.4.3 46TV Thermal Cycling

7.4.3.1 46Cumulative Cycles

7.4.3.2 47Ambient Pressure Thermal Cycling Substitution

7.4.3.3 47Qualification, Protoflight and Acceptance Temperatures

7.4.3.4 48Survival Heater Verification

7.4.3.5 48Temperature test tolerances

7.4.3.6 48Plateau Criteria

7.4.4 48Thermal Balance (TB)

7.4.4.1 48Balance Points

7.4.4.2 48Instrument Configuration

Contents vi

7.4.4.3 48Accuracy and Knowledge

7.4.4.4 49Steady State Criteria

7.5 49Test Condition Tolerances

8 52Acronyms

Contents vii

Page 1 of 52 Printed Friday, August 12, 2022

ID

GXIPORD1

GXIPORD2

GXIPORD3

GXIPORD4

GXIPORD5

GXIPORD6

GXIPORD10

GXIPORD11

GXIPORD12

GXIPORD13

GXIPORD14

GXIPORD15

GXIPORD700

GXIPORD696

GXIPORD698

Object Number

1.1

1.1.0-1

1.2

1.2.0-1

1.2.0-2

1.2.0-3

1.2.0-4

1.2.0-5

1.3

1.3.0-1

1.4

1.4.0-1

1.4.0-2

1.4.0-3

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

1 Scope

1.1 Identification

This Performance and Operational Requirements Document (PORD) sets forth the performance requirements for the National Oceanic and Atmospheric Administration (NOAA) Geostationary and eXtended Observations Imager (GXI).

1.2 Mission Review

The GXI is a multi-channel, visible through infrared, passive imaging radiometer used to measure environmental data as part of a 3-axis stabilized, geostationary weather satellite system. The GXI remotely collects imagery of the Earth’s surface (land and water) and atmosphere to aid in the prediction of weather and climate monitoring. The data provide adequate spatial, temporal and radiometric resolution to accurately monitor rapidly changing weather.

The GXI objectives are as follows:

a) Provide environmental data that will be used by NOAA and other public and private agencies to produce routine meteorological analyses and forecasts.

b) Maintain continuity of Geostationary Extended Observations (GeoXO) services to the user agencies.

c) Provide environmental data that will be used to expand knowledge of mesoscale and synoptic scale storm development and provide data that may be used to help in forecasting severe weather events. It will also be used for detection and tracking of clouds, fires, aerosols, and other applications.

The GXI provides data to the Ground System via the spacecraft communication system.

The Ground System takes the data, spacecraft telemetry data, orbit determination data and other required information and autonomously generates radiometrically calibrated and navigated (level 1b) data for the NOAA users.

The Ground System will be procured by the Government but will implement algorithms developed by the GXI contractor to satisfy performance requirements.

The Ground System will calibrate and then resample the data to generate Level 1b data on the fixed grid. Resampling requires that the raw imagery be adequately sampled to maintain radiometric accuracy after resampling.

1.3 Document Overview

This document contains all performance requirements for the GXI instrument and Ground Support Equipment (GSE). This document, the General Interface Requirements Document (GIRD), and the GXI Unique Instrument Interface Document (UIID) define all instrument to spacecraft interfaces for the GXI instrument.

1.4 Requirements Terminology

The following requirements terminology is used throughout this document:

The use of “shall” designates a requirement that must be met.

The use of “will” designates a statement of fact or intention of the government.

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ID

GXIPORD699

GXIPORD701

GXIPORD17

GXIPORD18

GXIPORD19

GXIPORD20

GXIPORD21

GXIPORD22

GXIPORD23

GXIPORD24

GXIPORD25

GXIPORD702

Object Number

1.4.0-4

1.4.0-5

1.4.0-6

1.5

1.5.0-1

1.5.0-2

1.5.0-3

1.5.0-4

1.5.0-5

1.5.0-6

1.5.0-7

1.5.0-8

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

The use of “may” designates that permission has been granted by the government.

The term “(TBD)” means, “to be determined” and is used when no value is available with subsequent study needed to obtain it.

The term “(TBR)” means “to be refined/reviewed” for a value that is subject to review for appropriateness and is subject to revision. The vendor is liable for compliance with the information marked “TBR” as if the “TBR” notation did not exist.

1.5 Definitions

Throughout this document, the following definitions apply:

Accuracy: Refers to the error in a measurement, that is the difference between the measurement result and the object to be measured (the measured or true value). It includes both systematic and random errors. Systematic errors must be estimated from an analysis of the experimental conditions and techniques. Random errors can be determined, and reduced, through repeated measurements under identical conditions.

Albedo: Refers to the fraction of the solar spectrum taken from the default MODTRAN solar irradiance file, version 4V1R1 (newkur.dat) that is reflected by the Earth at the top of the atmosphere assuming a Lambertian surface.

All requirements/all operational requirements: Refers to all performance characteristic or requirement in the GXIPORD, GXIUIID, and the GIRD.

Derived Noise Equivalent Delta Radiance (NEDN): Refers to the NEDN required to meet the Noise Equivalent Delta Temperature (NEDT) specification or Signal-to-Noise Ratio (SNR) specification.

Detector sample or element: Refers to the output of a physical detector after the Analog-to-Digital (A/D) converter and Time Delay and Integration (TDI) processing, if applicable.

Eclipse: Defined as when the solar disk is partially or completely occulted by the Earth or Moon, as viewed from the satellite.

Fixed-Grid Angles: Refers to North/South (NS) and East/West (EW) Euler angles defined as follows. Starting with the orbit reference frame (ORF) in GIRD62 at the ideal satellite location, a positive NS angle is a rotation of the ORF about its +x axis, and a positive EW angle is a subsequent rotation of the rotated frame about its +y axis. The +z axis of the final frame is the line of sight (LOS) represented by the EW and NS fixed-grid angles.

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ID

GXIPORD26

GXIPORD38

GXIPORD39

GXIPORD40

GXIPORD41

GXIPORD42

GXIPORD43

GXIPORD44

GXIPORD703

GXIPORD45

GXIPORD776

GXIPORD46

Object Number

1.5.0-9

1.5.0-10

1.5.0-11

1.5.0-12

1.5.0-13

1.5.0-14

1.5.0-15

1.5.0-16

1.5.0-17

1.5.0-18

1.5.0-19

1.5.0-20

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

Fixed Grid: Refers to a set of points in fixed-grid angle space that are uniformly-spaced in both coordinates and that define locations in a nadir-centered field of view from the perspective of an ideally-located satellite in geosynchronous orbit. Fixed grids for GXI have the following characteristics:

a) Each point in a fixed grid designates the center of a pixel.

b) The EW and NS angular spacing of the fixed grids for 0.25, 0.5, 1, and 2 kilometer channels is 7, 14, 28, and 56 microradians, respectively.

c) The ideal sub-satellite point is at the corner of a pixel on the 7, 14, 28, and 56 microradian fixed grids. This results in a larger pixel covering the same region as four pixels of the next smaller grid.

Full Disk: Defined as a 17.4 degree diameter disk centered at nadir, plus any additional imaging required for uncompensated non ideal orbit and image motion compensation.

Fully Functional Configuration: Being able to perform the following functions: scene radiance measurement; radiometric calibration; star sensing; on-orbit monitoring of calibration sources and instrument response changes; acquisition of sensor health and status data; generation of sensor, calibration, monitoring, health and status data streams; and reception and execution of command and control data.

Image: Refers to a full disk, superregional, or mesoscale image in the fixed grid.

Image Navigation: Refers to the determination of fixed grid angles referenced to the location on the GRS80 ellipsoid of each image pixel.

Image Registration: Refers to maintaining the spatial relationship between pixels within images, between images, and between channels.

Launch: The period of time between lift off and the separation of the satellite from the launch vehicle.

Mesoscale Region: Defined as the equivalent of a 1.6043 x 1.6043 degree, 1000 km x 1000 km nadir-viewed area.

Mission Allowable Temperatures (MAT): Mission Allowable Temperatures are the established range of temperatures that instrument units are permitted to experience while operating in orbit. MAT are established based upon analytical temperature predictions with appropriate margin based on the state of the thermal design. MAT encompasses worst-case operating temperature predictions, uncertainty, and any vendor desired temperature margin.

Navigation Error: Refers to the angular error of locations in the resampled fixed-grid image.

Non-operational Temperatures (NOT): Non-operational Temperatures are the established range of temperatures that instrument units are permitted to experience while not operating and not powered. NOT represent the permissible range while the hardware is powered off. Survival heaters maintain hardware at or above the cold NOT limits and passive design maintains hardware below the upper NOT limits. NOT are also known as non-operating MAT.

Pixel: Refers to data samples after resampling during the ground processing.

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ID

GXIPORD47

GXIPORD48

GXIPORD49

GXIPORD50

GXIPORD51

GXIPORD52

GXIPORD53

GXIPORD54

Object Number

1.5.0-21

1.5.0-22

1.5.0-23

1.5.0-24

1.5.0-25

1.6

1.6.0-1

1.6.0-2

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

Polarization Sensitivity: Defined as the ratio of the difference between maximum and minimum output to the sum of the maximum and minimum output obtained when the plane of incoming 100% linearly polarized radiation is rotated through 180 degrees.

Precision: Refers to the standard deviation of a statistically meaningful number of samples of a measurement.

Superregional: Defined as the equivalent of a 5000 kilometer East/West x 3000 kilometer North/South nadir-viewed area.

Transfer Orbit: The sequence of events that transpires to establish the GeoXO satellite on-station after the GeoXO satellite has separated from the launch vehicle.

Unit: A functional subdivision of a subsystem and generally a self-contained combination of items performing a function necessary for the subsystem's operation.

Examples are electronics unit and sensor unit.

1.6 Requirement Applicability

The requirements in this GXIPORD pertain to the GXI ‘system’, which may include motors, optics, detectors, signal processing electronics and software, and ground processing. The GXI contractor is not responsible for the whole Ground System, but certain specifications may require some level of ground processing after collection but before data distribution, i.e. decompression, re-sampling, and calibration.

All requirements apply over the entire life of the GXI. Requirements, such as Modulation Transfer Function (MTF) and Image Navigation and Registration (INR), apply after including level 1b ground processing impacts, except as indicated.

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ID

GXIPORD55

GXIPORD56

Object Number

2.0-1

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

2 Applicable Documents

The following form a part of this specification to the extent specified herein.

CCSDS Recommendation for Space Data System Standards, Image Data Compression, CCSDS 122.0-B-2

Structural Design and Test Factors of Safety for Spaceflight Hardware, NASA, Document Number NASA-STD-5001B

General Specification for Assemblies, Moving Mechanical, for Space and Launch Vehicles, Document Number MIL-A-83577B

Space Mechanisms Handbook, Document Number NASA TP-1999-206988

General Environmental Verification Specification For GSFC Flight Programs and Projects, Document Number GSFC-STD-7000A

AFSPCMAN 91-710, Air Force Space Command Manual 91-710 (AFSPCMAN 91-710), Range Safety Requirements

Standard General Requirements for Safe Design and Operation of Pressurized Missile and Space Systems, Document Number MIL-STD-1522A

GXI Radiance Upwelling, 418-XO-RPT-0076

Page 6 of 52 Printed Friday, August 12, 2022

ID

GXIPORD65

GXIPORD66

GXIPORD67

GXIPORD68

GXIPORD69

GXIPORD70

GXIPORD71

GXIPORD72

GXIPORD73

GXIPORD74

GXIPORD75

GXIPORD76

GXIPORD77

GXIPORD78

GXIPORD79

GXIPORD80

GXIPORD81

GXIPORD82

GXIPORD83

GXIPORD84

GXIPORD85

GXIPORD86

Object Number

3.1

3.1.1

3.1.1.0-1

3.1.1.0-2

3.1.1.0-3

3.1.1.0-4

3.1.1.0-5

3.1.1.0-6

3.1.1.1

3.1.1.1.0-1

3.1.1.1.0-2

3.1.1.1.0-3

3.1.1.2

3.1.1.2.0-1

3.1.1.2.0-2

3.1.1.3

3.1.1.3.0-1

3.1.1.3.0-2

3.1.1.3.0-3

3.1.1.3.0-4

3.1.1.3.0-5

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

3 Sensor Requirements

3.1 Sensor Definition

3.1.1 GXI Modes

The GXI shall execute commands to individually enable and disable each autonomous function.

The GXI shall initiate all commanded mode transitions in no more than 20 seconds after receipt of command.

The GXI shall make limits and triggers of autonomous functions changeable by command.

The GXI shall transition from its current mode to any other mode without causing permanent damage to itself.

The GXI shall indicate the mode of the instrument in housekeeping telemetry.

The GXI shall provide command and housekeeping telemetry functions in all powered modes.

3.1.1.1 Safe Mode

The GXI shall implement a Safe Mode.

The GXI shall be in a thermally and optically safe configuration for an indefinite period of time while in Safe Mode.

The GXI shall enter Safe Mode upon detection of internal faults capable of causing permanent damage to the instrument.

3.1.1.2 Normal Operational Mode

The GXI shall be in a fully functional configuration while in Normal Operational Mode.

The GXI shall meet all performance requirements while in Normal Operational Mode without receiving commands or data loads for a minimum of 7 days.

3.1.1.3 Instrument Diagnostic Mode

The GXI shall implement an Instrument Diagnostic Mode.

The GXI shall be in a fully functional configuration while in Instrument Diagnostic Mode.

The GXI shall by command send selected channels while in Instrument Diagnostic Mode.

The GXI shall by command send the individual measurement in those cases where TDI data is digitally processed off the focal plane while in Instrument Diagnostic Mode.

The GXI shall by command send data from all detectors while in Instrument Diagnostic Mode.

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ID

GXIPORD87

GXIPORD88

GXIPORD89

GXIPORD90

GXIPORD91

GXIPORD92

GXIPORD93

GXIPORD94

GXIPORD95

GXIPORD96

GXIPORD97

GXIPORD98

GXIPORD100

GXIPORD101

Object Number

3.1.1.3.0-6

3.1.1.3.0-7

3.1.1.3.0-8

3.1.1.3.0-9

3.1.1.4

3.1.1.4.0-1

3.1.1.4.0-2

3.1.2

3.1.2.1

3.1.2.1.1

3.1.2.1.1.0-1

3.1.2.1.1.0-2

3.1.2.1.2

3.1.2.1.2.0-1

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

The GXI shall by command send the same data both compressed and uncompressed if the data is capable of being compressed while in Instrument Diagnostic Mode.

The GXI shall by command send all bits from the A to D converter while in Instrument Diagnostic Mode.

The GXI shall by command perform electronic in-flight calibration while in Instrument Diagnostic Mode.

The GXI shall by command send dwell data (increased samples per second of a particular telemetry measurand) while in Diagnostic Mode.

3.1.1.4 Outgas Mode

The GXI shall implement an Outgas Mode.

The GXI shall sublimate and evaporate contaminants from hardware to prevent contamination from jeopardizing performance while in Outgas Mode.

3.1.2 On-Orbit Operations

3.1.2.1 Zones of Reduced Data Quality

3.1.2.1.1 Operational Zone

The GXI shall meet all of its performance requirements for all pixels in channels greater than 3 microns whose distance from the center of the uneclipsed portion of the sun is greater than 7.5 degrees.

The GXI shall meet all of its performance requirements for all pixels in channels less than 3 microns when the distance from the center of the sun to any part of the earth is greater than the limits in the Operational Zones Table.

Operational Zones Table

Channel Outer Limit Low light 10° All other reflective 30°

3.1.2.1.2 Restricted Zone

For all pixels in channels greater than 3 microns whose distance from the center of the uneclipsed portion of the sun is between the inner and outer limits shown in the Restricted Zones Table, the GXI shall meet all requirements, except for a factor of two degradation of the SNR and NEDT requirements stated in requirement number GXIPORD163, a factor of two degradation of the absolute accuracy requirement stated in GXIPORD226, and the navigation low-beta angle performance period associated with eclipse described in GXIPORD207.

Restricted Zones Table

Channel Inner Limit Outer Limit <4.5 micrometers 5° 7.5° All others 3° 7.5°

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ID

GXIPORD105

GXIPORD106

GXIPORD107

GXIPORD108

GXIPORD109

GXIPORD110

GXIPORD111

GXIPORD112

GXIPORD113

GXIPORD114

GXIPORD115

GXIPORD116

GXIPORD117

GXIPORD118

GXIPORD119

GXIPORD120

GXIPORD121

GXIPORD122

GXIPORD123

GXIPORD124

GXIPORD125

Object Number

3.1.2.2

3.1.2.2.0-1

3.1.2.2.0-2

3.1.2.3

3.1.2.3.1

3.1.2.3.1.0-1

3.1.2.3.2

3.1.2.3.2.0-1

3.1.2.3.3

3.1.2.3.3.0-1

3.1.2.4

3.1.2.4.0-1

3.1.2.4.0-2

3.1.2.4.0-3

3.1.2.4.0-4

3.2

3.2.1

3.2.1.1

3.2.1.1.0-1

3.2.1.1.0-2

3.2.1.1.1

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

3.1.2.2 Eclipse

The GXI shall be capable of continuous operation through eclipse periods.

During eclipse periods, for all channels with wavelengths greater than 3 microns, the GXI shall meet all requirements, except as noted in requirement number

GXIPORD207.

3.1.2.3 Operations After Maneuvers

3.1.2.3.1 Yaw Flip

The GXI shall meet all radiometric, coverage and INR requirements within 30 minutes after the spacecraft interface has returned to being within specification following a yaw flip.

3.1.2.3.2 Stationkeeping

The GXI shall meet all radiometric, coverage and INR requirements within 2 minutes after the spacecraft interface has returned to being within specification following spacecraft stationkeeping maneuvers.

3.1.2.3.3 Post Storage Activation

The GXI shall meet all requirements within 5 days of turn on after post storage activation for passively cooled detectors and 3 days for actively cooled detectors.

3.1.2.4 Detector Operating Temperatures

The detector operation temperatures shall be selectable by command.

The detector control temperature shall be in 1K increments or smaller.

The detector control temperature shall be at least +10K/-5K of the nominal operational temperature.

The precision on the control temperatures of the detectors shall be less than +/- 0.5 K.

3.2 Sensor Characteristics

3.2.1 Coverage

3.2.1.1 Imaging Modes

Routine operations, such as uploading commands and data to the GXI, shall not interfere with data collection in any imaging mode.

The GXI shall be capable of interrupting current operations by command and starting the acquisition of a new image, after an image coordinate upload, within 30 seconds.

3.2.1.1.1 Imaging Mode A

Page 9 of 52 Printed Friday, August 12, 2022

ID

GXIPORD126

GXIPORD131

GXIPORD132

GXIPORD135

GXIPORD136

GXIPORD137

GXIPORD138

GXIPORD139

GXIPORD140

GXIPORD141

GXIPORD142

GXIPORD143

GXIPORD144

GXIPORD145

GXIPORD146

Object Number

3.2.1.1.1.0-1

3.2.1.1.2

3.2.1.1.2.0-1

3.2.1.1.3

3.2.1.1.3.0-1

3.2.1.1.3.0-2

3.2.1.1.4

3.2.1.1.4.0-1

3.2.1.1.5

3.2.1.1.5.0-1

3.2.1.2

3.2.1.2.0-1

3.2.1.2.0-2

3.2.1.2.0-3

3.2.1.2.0-4

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

The GXI shall acquire concurrently:

a) Full Disks at 10 minute intervals

b) Superregional images at 5 minute intervals, any of which may be extracted from the full disk images if the timing is correct

c) A Mesoscale image at 30 second intervals

d) Any other observations required to meet radiometric and INR requirements

3.2.1.1.2 Imaging Mode B

The GXI shall acquire concurrently:

a) Full Disks at 5 minute intervals,

b) Any other observations required to meet radiometric and INR requirements.

3.2.1.1.3 Full Disk

In Mode A, an image of the Full Disk shall be acquired with all corresponding pixels in consecutive frames spaced at an average time of 10 minutes with a peak deviation of no more than ± 30 seconds.

In Mode B, an image of the Full Disk shall be acquired with all corresponding pixels in consecutive frames spaced at an average time of 5 minutes with a peak deviation of no more than ± 5 seconds.

3.2.1.1.4 Superregional

In Mode A, an image of the supperregional area shall be acquired with all corresponding pixels in consecutive frames spaced at an average time of 5 minutes with peak deviation of no more than +/- 30 seconds. The design may assume that the spacecraft x axis is parallel to the Earth’s equator within the accuracy as stated in the

GIRD.

3.2.1.1.5 Mesoscale

In Mode A, an image of a Mesoscale region viewed anywhere in the Field of Regard shall be acquired with all corresponding pixels in consecutive frames spaced at an average time of no more than 30 seconds apart with a peak deviation of +/- 5 seconds.

3.2.1.2 Flexible and Efficient Imaging Pattern

The GXI shall be designed such that the imaging patterns are flexible and programmable on-orbit.

The GXI shall accept commanded fixed grid coordinates for all Imaging Modes, whether on or off the Earth.

In addition to Full Disk images, the GXI shall have the capability to program least two superregional images at any given time.

The GXI shall autonomously adjust the Imaging Pattern to avoid imaging within a ground definable angle from the center of the sun.

Page 10 of 52 Printed Friday, August 12, 2022

ID

GXIPORD147

GXIPORD148

GXIPORD149

GXIPORD150

GXIPORD151

GXIPORD152

GXIPORD153

GXIPORD154

GXIPORD155

GXIPORD156

GXIPORD157

GXIPORD158

GXIPORD159

GXIPORD160

GXIPORD161

GXIPORD162

GXIPORD163

Object Number

3.2.1.2.0-5

3.2.1.2.0-6

3.2.1.2.0-7

3.2.1.3

3.2.1.3.0-1

3.2.1.4

3.2.1.4.0-1

3.2.1.4.0-2

3.2.1.5

3.2.1.5.0-1

3.2.1.5.0-2

3.2.1.6

3.2.1.6.0-1

3.2.2

3.2.2.1

3.2.2.1.0-1

3.2.2.1.0-2

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

If star sensing is used, the GXI shall autonomously onboard compute the position of stars and adjust the imaging pattern to acquire them (with any adjusted pattern still meeting all other requirements in this document).

The imaging pattern shall be definable by ground modifiable parameters such that full disk, superregional, and mesoscale images, other image regions and sizes, space looks, IR calibration, and star sensing are performed at any user-defined intervals that are consistent with the imaging rates used in predefined imaging modes. These data items will be uploaded during earlier operations and activated with a single command.

The GXI shall set the center location of each image to Fixed Grid Frame coordinates specified by command.

3.2.1.3 Field of Regard

The unvignetted Field of Regard (FOR) shall include a circle of at least 20 degrees in diameter with its center at the sub-satellite point and accounting for alignment errors as described in the GIRD.

3.2.1.4 Simultaneity

Corresponding pixels in all spectral channels shall be calculated from detector samples that are collected within 5 seconds of each other.

All adjacent pixels shall be calculated from detector samples collected within 30 seconds of each other.

3.2.1.5 Data Timeliness

The GXI shall contribute to the total data latency no more than: 50 seconds for a Superregional calibrated, navigated image; 20 seconds for a Mesoscale calibrated navigated image; and 50 seconds for a Full Disk calibrated, navigated image.

Data latency is measured from the time the instrument acquires all samples for a scene to the time the image is available for dissemination on the ground. The GXI contribution to data latency includes delay of delivery of data to the spacecraft and delay due to ground algorithm processing (i.e., resampling and INR).

3.2.1.6 Data Collection Overlap

The GXI shall generate each pixel from detector samples contained in a single data set.

3.2.2 Channel Definitions, NEDT, Dynamic Range

3.2.2.1 Baseline

The GXI shall collect imagery in the following 18 channels designated by their center wavelength in microns: 0.47, 0.64, 0.865, 0.91, 1.378, 1.61, 2.25, 3.9, 5.15, 6.185, 6.95, 7.34, 8.5, 9.61, 10.35, 11.2, 12.3, 13.3.

The GXI shall meet the SNR, and NEDT listed in the following Radiometric Precision Table.

Page 14 of 52 Printed Friday, August 12, 2022

ID

GXIPORD171

GXIPORD172

GXIPORD173

GXIPORD174

GXIPORD175

GXIPORD177

GXIPORD178

GXIPORD179

GXIPORD180

GXIPORD181

GXIPORD182

Object Number

3.2.2.2.1.0-4

3.2.2.2.2

3.2.2.2.2.0-1

3.2.2.2.3

3.2.2.2.3.0-1

3.2.2.2.3.0-2

3.2.2.3

3.2.2.3.0-1

3.2.3

3.2.3.1

3.2.3.1.0-1

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

When viewing the four government-supplied simulated upwelling radiance data sets in 418-XO-RPT-0076, the brightness temperature error due to the uncertainty in the spectral response between the 1% as-built response points shall be less than 1K for all channels with center wavelength greater than 3 microns.

3.2.2.2.2 Within Channel Spectral Response Uniformity

When viewing the simulated upwelling radiance data sets in 418-XO-RPT-0076 and when viewing the default solar irradiance spectrum from MODTRAN version 4V1R1 (newkur.dat) with the assumption that clouds have Lambertian reflectance with an albedo not less than 50%, the variation in radiance measured between the 1% as-built response points in each spectral channel, due to spectral differences over the focal plane, shall be less than the derived NEDN for all channels.

3.2.2.2.3 Out-of-Band Response

The out-of-band response is defined in the equation as one minus the integrated response between the as-built 1% response points divided by the integrated response from 0.3 microns to 20 microns. Out-of-band response shall be less than 0.25% of the signal for the 1.378 micron channel and 1% of the total signal for all other channels when viewing either a 300 K blackbody (for channel wavelengths greater than 3 microns) or a 100% albedo scene above the atmosphere assuming no attenuation.

Out-of-Band Response Equation

3.2.2.3 Low Light Visible Channel

The GXI shall include a low light level (5% albedo) visible (0.64 microns) imaging capability at 16:1 SNR with performance equivalent to the 0.64 microns visible channel except between the 10 and 30 degrees defined in GXIPORD98 where a factor of two degradation of the MTF requirement (defined as factor of two decrease in specified spatial frequency) stated in GXIPORD182 is imposed. (CCR-X00117)

3.2.3 Spatial Resolution and Sampling

3.2.3.1 System Modulation Transfer Function

The spatial resolution is defined by the sensor system sinusoidal MTF. The following MTF values (exact specification is in cycles/rad) are consistent with 0.3 kilometer resolution in the 0.64 micron channel, 0.5 kilometer resolution in the 0.47 and 0.865 micron channels, 1.0 kilometer resolution in the 0.91, 1.61, 2.25, 3.9, and 5.15 micron

Page 16 of 52 Printed Friday, August 12, 2022

ID

GXIPORD187

GXIPORD189

GXIPORD188

GXIPORD190

GXIPORD191

GXIPORD192

GXIPORD193

GXIPORD194

Object Number

3.2.3.2.0-2

3.2.3.2.0-3

3.2.3.2.0-4

3.2.3.2.0-5

3.2.3.2.0-6

3.2.3.2.0-7

3.2.3.3

3.2.3.3.0-1

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

The normalized radiance difference due to spatial response differences between corresponding pixels in any two spectral channels with a center wavelength greater than 3 microns located X (continuous variable) microradians from the edge of a 1000 by 1000 microradian or larger target with radiance equal or greater than 300 K surrounded by a large region of radiance equal to or less than 240 K shall agree to within 4 % of the step radiance difference for an rms over the sampling-to-edge phasing and the channel-to-channel relative phasing. The calculation of this normalized difference is expressed in equation form below.

Here the overbar represents an average over multiple samples located well away from the edge. This normalized radiance difference due to spatial response differences applies in all four directions, i.e. left of, right of, above, and below the target box. The values of X include all distances between +84 microradians and -84 microradians.

Any efforts to blur or enhance channel resolution to match that of other emissive (greater than 3 microns) channels shall be performed in ground system software, not within the instrument.

The reflectance difference due to spatial response differences between corresponding pixels in any two spectral channels with a center wavelength less than 3 microns located X (continuous variable) microradians from an edge of a 1000 by 1000 microradian or larger target with radiance equal to Nmax (see requirement GXIPORD165) surrounded by a large region of radiance equal to or less than 5% Nmax shall be less than 4% of the step function for an rms over the sampling-to-edge phasing and the channel-to-channel relative phasing.

Any efforts to blur or enhance channel resolution to match that of other reflective (less than 3 microns) channels shall be performed in ground system software, not within the instrument.

3.2.3.3 Ringing from a Sharp Edge

For both the North/South and East/West edges, the GXI shall not overshoot the top of an edge or undershoot the bottom of edge by more than 2% of the height of the edge where:

a) The height and the overshoot/undershoot are measured in radiance units.

b) The edge delineates a 10% albedo region from a 90% albedo region for channels less than 3 microns.

c) The edge delineates a 240K region from a 300K region for channels greater than 3 microns.

d) The overshoot is averaged over all resampling phases of the detector sample grid to pixel grid and edge position to detector sample grid.

Page 17 of 52 Printed Friday, August 12, 2022

ID

GXIPORD199

GXIPORD200

GXIPORD201

GXIPORD202

GXIPORD203

GXIPORD204

GXIPORD205

GXIPORD206

GXIPORD207

GXIPORD208

GXIPORD209

GXIPORD210

GXIPORD211

GXIPORD212

GXIPORD213

GXIPORD214

GXIPORD215

Object Number

3.2.4

3.2.4.1

3.2.4.1.0-1

3.2.4.2

3.2.4.2.0-1

3.2.4.2.0-2

3.2.4.2.1

3.2.4.2.1.0-1

3.2.4.2.1.0-2

3.2.4.2.2

3.2.4.2.2.0-1

3.2.4.2.2.0-2

3.2.4.2.3

3.2.4.2.3.0-1

3.2.4.2.4

3.2.4.2.4.0-1

3.2.4.2.5

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

3.2.4 Image Navigation and Registration

3.2.4.1 Star Sensing

If the GXI requires star coordinates on-board, the GXI shall have an on-board catalog that is nominally sufficient for the life of the mission but is loadable and modifiable from ground.

3.2.4.2 INR Performance Requirements

All INR requirements listed herein refer to location error of the fixed-grid pixels; i.e., the requirements apply to the end-to-end system, taking all instrument, spacecraft, and ground processing effects into account. Unless otherwise specified, all INR requirements in this document are specified as North/South and East/West angles, in microradians, 3-sigma, and refer to all hours of operation.

In the context of GXI INR, 3-sigma error is defined to be equal to the 99.73rd percentile of the absolute values of all INR error observations collected over each 24-hour period from local noon to local noon. When INR requirements are temporarily suspended, due to Sun/Earth geometry or maneuver outages (including recovery time), the raw errors during the requirements suspension period should be ignored.

3.2.4.2.1 Navigation

Image navigation error shall not exceed 21 microradians, 3-sigma, per axis, excluding the low-beta angle performance period associated with eclipse in GXIPORD207.

For up to a four-hour period near local midnight when the beta angle is within +/-11 degrees, the GXI navigation error shall not exceed 32 microradians, 3-sigma, per axis.

The phasing of the low-beta angle performance period associated with eclipse relative to local midnight may be design-specific.

3.2.4.2.2 Frame-to-Frame Registration

Frame-to-frame registration error shall not exceed 17.6 microradians, 3-sigma, per axis, for channels with a fixed grid resolution of 1 km or less. Frame-to-frame registration error is the difference in navigation error for any given pixel in two consecutive images within the same channel.

Frame-to-frame registration error shall not exceed 23 microradians, 3-sigma, per axis, for channels with a fixed grid resolution of 2 km.

3.2.4.2.3 Within Frame Registration

Within an image in the same channel, any two pixels shall be separated by the known fixed distance to within 21 microradians, 3-sigma, measured radially.

3.2.4.2.4 Collection-to-Collection Registration

Collection-to-collection registration error shall not exceed 7.8 microradians, 3-sigma, per axis, where the collection-to-collection error is the relative location error of adjacent pixels across a collection boundary within the same channel.

3.2.4.2.5 Channel-to-Channel Registration

Page 18 of 52 Printed Friday, August 12, 2022

ID

GXIPORD216

GXIPORD221

GXIPORD222

GXIPORD223

GXIPORD224

GXIPORD225

GXIPORD226

GXIPORD227

GXIPORD228

GXIPORD229

GXIPORD230

GXIPORD231

GXIPORD233

Object Number

3.2.4.2.5.0-1

3.2.5

3.2.5.1

3.2.5.1.1

3.2.5.1.1.0-1

3.2.5.1.2

3.2.5.1.2.0-1

3.2.5.2

3.2.5.2.1

3.2.5.2.1.0-1

3.2.5.2.1.0-2

3.2.5.2.1.0-3

3.2.5.2.1.0-4

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

Channel-to-channel registration error, or co-registration, is the difference in navigation errors between spectral channels for any given pixel in the same frame. The channel-to-channel registration requirements depend on the fixed-grid resolutions of the channels. Co-registration errors between any two spectral channels shall not exceed the values shown in the Channel-to-Channel Registration table, on a 3-sigma, per axis basis.

Channel-to-Channel Registration Table

2-km 1-km 0.5-km 0.25-km 2-km 11.2 microradians 11.2 microradians 11.2 microradians 11.2 microradians 1-km -- 6.0 microradians 6.0 microradians 6.0 microradians 0.5-km -- -- 6.0 microradians 5.0 microradians

3.2.5 Radiometric Accuracy and Precision

3.2.5.1 Calibration and Accuracy for Wavelengths Greater than 3 Microns

3.2.5.1.1 Full Aperture Calibration

The GXI shall have full system, end-to-end, and full aperture on-board calibration channels with wavelengths greater than 3 microns.

3.2.5.1.2 Absolute Accuracy

The GXI data shall be calibrated to an absolute accuracy with traceability to NIST of +/- 1 K (one sigma) at a 300 K reference temperature (Ref SOW for details on traceability).

3.2.5.2 Repeatability

3.2.5.2.1 Pixel-to-Pixel

For all channels, while viewing a stable, uniform calibration source over expected geostationary environmental conditions and calibration frequency, the GXI shall have a pixel-to-pixel repeatability less than the derived NEDN.

Channels with wavelengths less than 3 microns will be characterized as if viewing a 100% albedo calibration source. Channels with wavelengths greater than 3 microns will be characterized as if viewing a 300 K temperature calibration source.

The pixel-to-pixel repeatability is calculated as follows: for each 3 row by 10 column subset of the image the row average is calculated for each row, the RMS of the row averages is then calculated and must be less than the derived NEDN. This value is then averaged Nimage times where Nimage is the number of samples required to state at the 90% confidence level that the requirement has been met for all possible locations on the full disk.

Page 19 of 52 Printed Friday, August 12, 2022

ID

GXIPORD233

GXIPORD234

GXIPORD235

GXIPORD237

GXIPORD238

GXIPORD239

GXIPORD240

Object Number

3.2.5.2.1.0-4

3.2.5.2.2

3.2.5.2.2.0-1

3.2.5.2.2.0-2

3.2.5.2.3

3.2.5.2.3.0-1

3.2.5.2.3.0-2

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B disk. full on the locations possible allfor met be toappliesequation This jcolumn i, rowfor valuepixel resampled theis

i. rowfor mean row theis pixels. 30for mean theis

N

NEDN Derived image ji j jii i j ji

N j i i

P

PR

PR

where

RR

image

Pixel-to-Pixel Equation

3.2.5.2.2 Collection-to-Collection

For each channel with a wavelength greater than 3 microns, while viewing a stable, uniform 300K temperature calibration source over expected geostationary environmental conditions and calibration frequency, the difference in calibrated pixel radiance between collection boundaries in a resampled image shall be less than the derived NEDN. The collection-to-collection repeatability is evaluated by computing the RMS of the difference of neighboring row means at collection boundaries for superregional images. NBoundaries is the number of boundaries required to state at the 90% confidence level that the requirement has been met. In the resampled image, a boundary is where neighboring North/South pixels come from different collected images.

long pixels M of rowhigh pixel one a ofmean theis

NEDN Derived

,0

M i i

South sNBoundarie i

North

P M

R where

RR

sNBoundarie

Collection-to-Collection Equation

3.2.5.2.3 Channel-to-Channel

For each channel with a wavelength greater than 3 microns, while viewing a stable, uniform 300K temperature calibration source over expected geostationary environmental conditions and calibration frequency, the GXI shall have a channel-to-channel repeatability of less than 0.2 Kelvin. The channel-to-channel repeatability is evaluated by computing the RMS of superregional image mean differences between each channel pair, over a series of NImages. NImages is the number of images required to state at the 90% confidence level that the requirement has been met.

Page 20 of 52 Printed Friday, August 12, 2022

ID

GXIPORD240

GXIPORD242

GXIPORD243

GXIPORD244

GXIPORD246

GXIPORD247

GXIPORD248

Object Number

3.2.5.2.3.0-2

3.2.5.2.4

3.2.5.2.4.0-1

3.2.5.2.4.0-2

3.2.5.2.5

3.2.5.2.5.0-1

3.2.5.2.5.0-2

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended a Superregional image ofmean the is microns 3an greater th s wavelengthpair with Channel 2,1

Im

2 . 0

1 ,1

0 , 2 , 1Im

1 , M N j i j i c r ages N r c r

T

NM

T c c where

T T ages N

K

Channel-to-Channel Equation

3.2.5.2.4 Image-to-Image

For each channel with a wavelength greater than 3 microns, while viewing a stable, uniform 300K temperature calibration source over expected geostationary environmental conditions and calibration frequency, the GXI shall have an image-to-image repeatability of less than 0.2 Kelvin. The image-to-image repeatability is evaluated by computing the RMS of consecutive superregional image differences over a series of NImages for each channel. NImages is the number of images required to state at the 90% confidence level that the requirement has been met.

Superregional image a ofmean the is

1-NImages

2 . 0

1 ,1

0, 2 Im j i r ages N r r

P

NM

I where

I I K

Image-to-Image Equation

3.2.5.2.5 Blackbody Calibration-to-Calibration

For each channel with a wavelength greater than 3 microns, while viewing a stable, uniform 300K temperature calibration source over expected geostationary environmental conditions and calibration frequency, the GXI shall have a calibration-to-calibration repeatability of less than 0.2 Kelvin. The calibration-to-calibration-repeatability is evaluated by computing the RMS of consecutive superregional image mean differences with a blackbody calibration event between the images. Ncals is the number of image pairs required to state at the 90% confidence level that the requirement has been met.

The calculation is done in radiance units and converted to temperature with a reference temperature of 300 K in the final step.

Page 21 of 52 Printed Friday, August 12, 2022

ID

GXIPORD250

GXIPORD251

GXIPORD252

GXIPORD253

GXIPORD256

GXIPORD257

GXIPORD258

GXIPORD259

GXIPORD260

Object Number

3.2.5.2.5.0-3

3.2.5.3

3.2.5.3.0-1

3.2.5.3.0-2

3.2.5.3.0-3

3.2.5.3.0-4

3.2.5.4

3.2.5.4.1

3.2.5.4.1.0-1

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended

Superregional image a ofmean the is

2 . 0

1 ,1

0 , j i after NCals r before

P

NM

I where

I I NCals

K

Blackbody Calibration-to-Calibration Equation

3.2.5.3 Coherent Noise

For all channels, while viewing a stable, uniform calibration source over expected geostationary environmental conditions and calibration frequency, the GXI shall have no spatial coherent noise spectral component exceedances. The spatial coherent noise is defined as the variation in the 2-D Fourier transform of the pixel output of an inscribed square of a full disk sized region following all calibration, sampling and detrending. An exceedance is defined as any spatial frequency whose scaled Fourier coefficients are greater than 25 percent of the derived NEdN. The scaled Fourier coefficients are defined using the following equations to scale the amplitude to match the amplitude of a single harmonic.

N kj NljxlkX

)1)(1( 1 ),(),(

Ni

N e /2

M kj MjlXklX

)1)(1( 12 ),(),(

Mi

M e /2

NM

X X a

Where x(j,l) is the image radiances, N and M are the image size in pixels and Xa are the scaled Fourier coefficients. Detrending allows the removal of scene trends by subtracting the filtered scene using a square box car filter that is 10% of the minimum scene dimension. Edge effects of detrending may be reduced by using a symmetric boundary condition.

Note: The width of bin is defined by the fixed grid spacing. Channels with wavelengths less than 3 microns will be characterized as if viewing a 100% albedo calibration source. Channels with wavelengths greater than 3 microns will be characterized as if viewing a 300 K temperature calibration source.

3.2.5.4 Calibration of Channels Less Than 3 Microns

3.2.5.4.1 On-Board Calibration

The GXI shall have an on-board calibration capability for the reflective (less than 3 microns) channels, except 1.378 micron channel, that provides accuracy with traceability to NIST of +/- 3% (one sigma) or less in the earth albedo measurements for the scene of 100% albedo.

Page 22 of 52 Printed Friday, August 12, 2022

ID

GXIPORD261

GXIPORD262

GXIPORD263

GXIPORD264

GXIPORD265

GXIPORD266

GXIPORD267

GXIPORD268

GXIPORD269

GXIPORD270

GXIPORD271

GXIPORD272

GXIPORD273

Object Number

3.2.5.4.1.0-2

3.2.5.4.1.0-3

3.2.5.4.1.0-4

3.2.5.5

3.2.5.5.0-1

3.2.5.5.0-2

3.2.5.6

3.2.5.6.1

3.2.5.6.1.0-1

3.2.5.6.2

3.2.5.6.2.0-1

3.2.5.7

3.2.5.7.0-1

418-XO-GXIPORD-0117, RM Version, Geostationary and eXtended Observations (GeoXO) Imager (GXI) Performance and Operational

Requirements Document (PORD) Phase B

The GXI shall have an on-board calibration capability for the 1.378 micron channel that provides an accuracy with traceability to NIST of +/- 4% (one sigma) or less in the earth albedo measurements traceable to NIST standards for the scene of 100% albedo.

The GXI shall have an on-board calibration capability for the reflective (less than 3 microns)…