Daniel Haas

Hyperspectral analysis and target detection system for the Adaptive Spectral Reconnaissance Program (ASRP)

A multiprocessor version of the ORASIS hyperspectral analysis program has been implemented in support of the ASRP. In brief, the long-term technical objectives of the ASRP are to demonstrate the feasibility and military utility of real-time target detection from uncrewed air vehicles using hyperspectral data. This paper presents a preliminary assessment of ORASIS performance and describes the ORASIS development effort designed to meet the ASRP goals. Real-time performance of the analysis program and its potential effectiveness as a target detection method are demonstrated.

Real-time analysis of hyperspectral data sets using NRL's ORASIS algorithm

The covered lantern project was initiated by the central MASINT Technology Coordination Office to demonstrate the tactical use of hyperspectral imagery with real time processing capability. We report on the design and use of the HYCORDER system developed for Covered Lantern that was tested in June 1995. The HYCORDER system consisted of an imaging spectrometer flying in a Pioneer Uncrewed Aeronautical Vehicle and a ground based real time analysis and visualization system. The camera was intensified allowing dawn to dusk operation. The spectral information was downlinked to the analysis system as standard analog video. The analysis system was constructed from 17 Texas Instrument C44 DSPs controlled by a 200 MHz Pentium Pro PC. A real time, parallel version of NRLs optical real-time adaptive spectral identification system algorithm was developed for this system. The system was capable of running continuously, allowing for broad area coverage. The algorithm was adaptive, accommodating changing lighting conditions and terrain. The general architecture of the algorithm will be discussed as well as results from the test.

New results from the ORASIS/NEMO compression algorithm

We present results from an improved ORASIS (Optical Real-time Adaptive Spectral Identification System) hyperspectral-data compression-algorithm that is being implemented on the Naval EarthMap Observer (NEMO) satellite. The algorithm is shown to produce results that are statistically improved from previous findings. To augment the statistical testing, the re-inflated data are run through analysis programs such as unsupervised classification. ORASIS compression is a series of algorithms. The first algorithm, the exemplar selector process (ESP), is a variation of Learned Vector Quantization (LVQ) that builds up a relatively small set of spectra to represent the full data set. Subsequent algorithms find approximate endmembers for the exemplar set and project the set into the space defined by the endmembers. Both the ESP and the projection process contribute to the compression of the data. The obtainable compression ratios vary with scene content and other factors but ratios between 10:1 and 30:1 are possible. The compressed data format is designed to allow direct access to individual pieces of the data without reinflation of the entire data set. Details of the hardware implementation of the Imagery On-Board Processor (IOBP) of NEMO is discussed, as well as the use of the compressed data on the ground.

Evidence of HF-driven wave interactions in the ionospheric focused heating experiment

The Ionospheric Focused Heating rocket experiment created an ionospheric hole above the Arecibo HF radiowave heater by the release of an electron-attachment chemical. The hole served as a focusing lens for HF waves at 5.1 MHz and produced various plasma wave effects measured by onboard diagnostic instruments. In this report, we present evidence for the occurrence of plasma wave interactions driven by the HF pump at altitudes where the pump frequency is near the electron plasma frequency and one-half the electron plasma frequency. These interaction regions are observed on the upper side of the ionospheric hole. The data suggest that the frequency and wavenumber matching requirements for coupled waves are met in these regions.

Rocket‐borne downconverter system for measuring space plasma turbulence

For research into space plasma turbulence, we have developed a number of space‐flight instruments for making in situ measurements of plasma wave activity. One of these instruments, the NRL downconverter, is used to measure plasma waves in the 2‐ to 20‐MHz frequency range by downconverting a 100‐kHz band of frequencies to the baseband. Input frequency tuning is controlled by an imbedded microcomputer, and can be programmed to scan in any desired frequency pattern. The in‐phase and quadrature receiver outputs, each having a 50‐kHz bandwidth, are processed externally by digital signal processors (DSP). The receiver achieves 35 dB of sideband rejection using a hybrid quadrature mixer design, which incorporates an analog front end with digital signal processing. This design yields 15 dB of improved sideband rejection over more conventional analog techniques. The microcomputer control, DSP processing, and modular design contribute to the flexibility of the receiver, which has allowed the system to be used on a ...

Evaluation of endmember selection techniques and performance results from ORASIS hyperspectral analysis

In this work, we generate ROC curves on real and synthetic scenes and develop scoring methods to evaluate the performance of the ORASIS hyperspectral algorithm. The goal of this effort is to improve the overall performance of ORASIS, focusing on the endmember selection methods. ROC curve evaluations have been performed on hyperspectral data sets from different scenes. We have scored by target and by target pixel. A scene generator has been developed allowing many features: combination of real or synthetic background and multiple, distinct targets; user-defined angle of target spectrum to background subspace; and user-specified non-uniform target/background transparency.

Frequency‐Shifted Signature of the HF Pump in the Ionospheric Focused Heating Experiment

Ionospheric heating experiments have begun to examine interactions at altitudes where the heater HF wave frequency matches the local electron plasma frequency. We discuss the frequency-shifted signature observed by radiowave receivers on a rocket launched into the HF beam and approaching the interaction altitude. The frequency shifts associated with the upgoing (transmitted) and the downgoing (reflected) waves arise from the Doppler effect and changes in the wave vector. The characteristic spectral signature provides a method to locate the reflection altitude accurately. Generally, the ratio of intensities of upgoing and downgoing waves decreases as the reflection altitude is approached.

Space‐flight digital signal processor system for on‐board processing of experiment data

We have developed a digital signal processor (DSP) system to extend the capabilities of a variety of scientific instruments used to make in situ ionospheric plasma measurements from sounding rockets and spacecraft. The DSP system is extremely flexible due to the use of a field programmable gate array, sigma‐delta analog‐to‐digital converters, and a highly integrated single‐chip DSP. Using virtually identical circuitry, we have operated DSP systems processing data from low‐frequency electric field detectors, Langmuir probes, and several radio‐frequency receivers on several sounding rockets and spacecraft with different digital telemetry interfaces. The DSP system provides three major improvements to our instruments: (1) reduced telemetry bandwidth (data) requirements, (2) improved signal‐to‐noise ratio, and (3) digital antialiasing filtering. We describe our DSP system and show three examples of how we have implemented it with our instruments. Similar systems should be of interest to researchers in many fi...

On-board hyperspectral compression and analysis system for the NEMO satellite

The primary mission of the Naval EarthMap Observer (NEMO) is to demonstrate the importance of hyperspectral imagery in characterizing the littoral battlespace environment and littoral model development. NEMO will demonstrate real time on-board processing and compression of hyperspectral data with real-time tactical downlink of ocean and surveillance products directly from the spacecraft to the field. The NRLs Optical Real-time Adaptive Spectral Identification System (ORASIS) will be deployed on a 3.8 Gflop multiprocessing computer, the Imagery On-Board Processor (IOBP), for automated data analysis, feature extraction and compression. NEMOs wide area coverage (106 km2 imaged per day), as well as power and cost constraints require data compression between 10:1 and 20:1. The NEMO Sensor Imaging Payload (SIP) consists of two primary sensors: first, the Coastal Ocean Imaging Spectrograph (COIS) is a hyperspectral imager which records 60 spectral bands in the VNIR (400 to 1000 nm) and 150 bands in the SWIR (1000 to 2500 nm), with a GSD of either 30 or 60 meters; and second, the 5 m GSD Panchromatic Imaging Camera (PIC). This paper describes the design and implementation of the data processing hardware and software for the NEMO satellite.