Special Coverage


Slot-Sampled Optical PPM Demodulation

Algorithms enable a post-processing receiver architecture that uses a fixed-rate ADC sample capture technology as an alternative to real-time receiver architecture. NASA’s Jet Propulsion Laboratory, Pasadena, California In order to demodulate an optical PPM signal, the receiver must align its slot clock to that of the received waveform to count the number of arrivals within each slot. The large bandwidth expansion factor of PPM, M/log2(M) requires a prohibitively large sample rate when a fixed sample clock N times greater than the slot frequency is used to provide a slot timing resolution of 1/Nth of a slot period. Alternative techniques that achieve slot alignment resolution through adjustment of the phase of the sample clock to align with the slot boundary require custom hardware and are not compatible with post-processing receiver architectures that use fixed-rate analog-to-digital (ADC) sample capture technology.

Posted in: Information Sciences, Electronics & Computers, Briefs


Small-Object Detection via Fast Discrete Curvelet Transform

NASA’s Jet Propulsion Laboratory, Pasadena, California The detection of distant objects in an image is relevant to applications in defense, security, and robotics. Successfully detecting objects of interest has been a common problem with respect to intelligent computer vision. Automatic target recognition (ATR) systems have been formulated and employed in numerous ways to tackle the difficulty of unsupervised targeting.

Posted in: Information Sciences, Electronics & Computers, Briefs


Real-Time Minimization of Tracking Error for Aircraft Systems

Direct adaptive control looks at errors and decides if and when corrections are needed. Ames Research Center, Moffett Field, California In many cases when an aircraft/spacecraft vehicle encounters a failure (such as a jammed control or loss of a part), there are still enough redundant actuation mechanisms to safely maneuver the vehicle. However, most pilots/autonomous systems are unable to adapt to the altered configuration and learn to control the damaged aircraft in the very short time available for safe operation. Fortunately, the flight computer may have the necessary information as well as bandwidth available to learn the new dynamics and determine mechanisms to control the vehicle quickly. The flight computer needs an intelligent controller that flies the vehicle with the baseline controller during normal conditions, and adapts the design when the vehicle suffers damage. Using information about the vehicle from all the available sensors, the system determines whether the vehicle is damaged. Direct adaptive control (DAC) looks directly at the errors, and updates the control law accordingly. This technology looks not just at the tracking error, but rather its characteristics over time to determine whether the controller needs to be adapted or left alone. This is typically fast and meets the timing considerations for aircraft/spacecraft system implementation.

Posted in: Physical Sciences, Data Acquisition, Briefs, TSP


Detecting an Extreme Minority Class in Hyperspectral Data Using Machine Learning

Automated classifiers can detect surface sulfur in orbital remote sensing observations. NASA’s Jet Propulsion Laboratory, Pasadena, California Orbital remote sensing provides a powerful way to efficiently survey targets for features of interest in inaccessible regions of the Earth as well as on other planets. One such feature of astrobiological relevance is the presence of surface sulfur deposits, which may be present on icy moons such as Europa. All hyperspectral instruments face the difficult task of spectral feature selection (finding the spectral bands that matter), especially those that operate in previously unstudied arenas encountered in planetary missions. This software demonstrates how manually annotated labels can enable automated feature discovery that boosts science return.

Posted in: Electronics & Computers, Data Acquisition, Briefs


KSC Spaceport Weather Data Archive

John F. Kennedy Space Center, Florida The Spaceport Weather Data Archive provides a fully searchable database of weather data gathered at Kennedy Space Center and the Cape Canaveral Air Force Station. Weather data includes wind, temperature, and humidity data from a surface meteorological tower network; upper air soundings from both weather balloons and radar wind profilers; and data from the extensive rain gauge network. Not only can the user easily retrieve data and download it, but the user can also view graphically the weather data on a map overlay. For example, the user can enter search criteria to view all lightning strikes ending at a particular date/time, and graphically see the lightning strikes color-coded based on elapsed time for the prior seven hours. A unique feature of the software is the capability to invoke an automated playback for cloud-to-ground lightning events on a geographic overlay for a selected date and time interval.

Posted in: Information Sciences, Electronics & Computers, Data Acquisition, Briefs, TSP


Visualizing Acquisition, Processing, and Network Statistics Through Database Queries

NASA’s Jet Propulsion Laboratory, Pasadena, California Given a date range, the UAVSAR MySQL database is queried to evaluate data acquisition, processing status, and network performance, and uses the Google Charts API to dynamically return images of pie and bar charts to visualize processing and network statistics. The MySQL database is populated with relevant data that includes processing status, as well as network performance (ping and sample file downloads). Then, using the open Google Charts API, the metrics are displayed for any desired date range.

Posted in: Information Sciences, Electronics & Computers, Data Acquisition, Briefs


Simulating Data Flow via Multiple Secure Connections

Goddard Space Flight Center, Greenbelt, Maryland A software simulator was developed to simulate data flow from the Interface Data Processing Segment (IDPS) to the Science Data Segment (SDS) for the NPOESS Preparatory Project (NPP) via multiple Secure FTP (sftp) connections. The simulator is a multi-threaded Java program that handles the continuous sftp transfer of large amounts of data with some error-handling capabilities built in.

Posted in: Software, Data Acquisition, Briefs