The NASA / JPSS Airborne Sounder Testbed - Interferometer (NAST-I) is a well-proven airborne remote sensing system, which has flown in 19 previous field campaigns aboard the high altitude NASA ER-2, Northrop Grumman / Scaled Composites Proteus, and NASA WB-57 aircraft since initially being flight qualified in 1998. While originally developed to provide experimental observations needed to finalize specifications and test proposed designs and data processing algorithms for the Cross-track Infrared Sounder (CrIS) flying aboard the Suomi National Polar-orbiting Operational Environmental Satellite System (NPOESS) Preparatory Project (SNPP) and the Joint Polar Satellite System, JPSS (formerly NPOESS, prior to program restructuring), its unprecedented data quality and system characteristics have contributed to a variety of atmospheric research and measurement validation objectives. This paper will provide a program overview and update, including a summary of measurement system capabilities, with a primary focus on postmission ground testing and characterization performed subsequent to the recently conducted Suomi NPP (SNPP) airborne field campaign.
The NPOESS / NASA Airborne Sounder Testbed - Interferometer (NAST-I) is a well-proven airborne remote sensing
system, which has flown in 18 previous field campaigns aboard the high altitude NASA ER-2, Northrop Grumman /
Scaled Composites Proteus, and NASA WB-57 aircraft since initially being flight qualified in 1998. While originally
developed to provide experimental observations needed to finalize specifications and test proposed designs and data
processing algorithms for the Cross-track Infrared Sounder (CrIS) to fly on the National Polar-orbiting Operational
Environmental Satellite System (NPOESS) Preparatory Project (NPP) and the Joint Polar Satellite System, JPSS
(formerly NPOESS, prior to recent program restructuring), its unprecedented data quality and system characteristics
have contributed to a variety of atmospheric research and measurement validation objectives. This paper will provide a
program overview and update, including a summary of measurement system capabilities, select scientific results, and
recent refurbishment activities.
In July 2006, the Department of Energy (DOE) National Nuclear Security Administration (NNSA)
initiated a new project in their remote sensing test and evaluation program. Upwelling and downwelling
radiance ground truth measurements have been advanced as a result of this project. Upwelling
radiance measurements are used for the spectral characterization of calibration targets, and downwelling
measurements are used to profile the temperature and moisture within the atmospheric column
above these targets. These measurements will be used for the development and improvement of
atmosphere compensations algorithms, as well as for the evaluation of the radiometric accuracy of
other remote sensing systems. In order to meet stringent wavelength and radiometric calibration
requirements, the selected technology is based on a Michelson interferometer spectrometer equipped
with an internal calibration unit. The proposed configuration facilitates precise radiometric accuracy
for target measurements, as well as concurrent temperature and moisture profiling of the atmosphere's
Planetary Boundary Layer (PBL) above the target. In this paper we describe the instrument approach
and its configuration. We also present results demonstrating the instrument performance. Atmospheric
sounding results are compared to measurements made with other sounding systems at the ARM site in
Oklahoma.
In June 2005, a newly develop long wave Focal Pane Array (FPA), based on photo-voltaic technology was delivered to
the Defense Research & Development of Canada (DRDC). This development was part of technological Demonstration
program that was founded by the DRDC. This paper will describe the FPA configuration along with its performance
assessment configured in the Air PIRATE FTIR spectrometer. Air PIRATE is an airborne version of the hyper spectral
spectrometer used by the Canadian Defense for target identification, as well as chemical agent identification.
KEYWORDS: Fourier transforms, Digital signal processing, Spectroscopy, Data acquisition, Sensors, Interferometers, Control systems, Analog electronics, Signal detection, Field programmable gate arrays
Advance of digital electronic technology into the signal processing domain facilitates significant advancement in the ability to control the scanning mechanisms of Fourier Transform Spectrometers (FTS). A generic digital controller for FTS has been developed and is now being offered as a commercial product to upgrade most commercially available FTS that use a He-Ne laser as their metrology system. This controller replaces the conventional analog signal from the laser fringes with a digital signal using a dedicated DSP and creates a more precise feedback control of the FTS scan mechanism.
Both Fourier Transform Infrared (FTIR) spectrometers and sampling techniques have seen a paradigm shift over the past 20 years. Infrared (IR) spectroscopy using the mid IR “fingerprint” region shows excellent specificity for determining the presence and quantity of well over 50000 organic chemical species. Tiny amounts of sample suffice for identification using a chemically inert scratch resistant diamond micro internal reflection crystal. For air quality, FTIR
can be used as a point monitor, sniffing air samples in an IR cell or using a long open-air path with a remote reflector or direct passive remote sensing. This makes IR ideal for first responders and haz/mat professionals provided the FTIR is compact, rugged and easy to use in the field. Already FTIR is widely used in industrial plants often directly at the process. In parallel FTIR is increasingly used in mobile field environments including airborne platforms as well as for
satellite-based sounders. This paper presents a resume of the evolution of FTIR and sampling technology and the boundaries of applicability of field deployed FTIR chemical sensors for the assessment of suspect substances as well as air pollution at the site of an emergency situation.
KEYWORDS: Receivers, FT-IR spectroscopy, Modulation, Sensors, Signal detection, Transmitters, Signal processing, Interferometers, Beam splitters, Signal to noise ratio
Fourier Transform Infrared Radiometers (FTIRs) are relatively new instruments in the applications of spectral radiometric characterization of targets. One of these FTIR instruments has been modified to provide a modulated spectrum as a source quantity. Interferometric scan signals are transmitted by microwave radio to an infrared receiver downrange in order to synchronize the detection of the modulated signals. The receiver uses the synchronization signals and the modulated infrared signals to obtain a source spectrum after propagation through the atmosphere. The technique appears to give good relative transmission estimates even up to 4 kilometers.
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