Keyword: Noise

Briefs: Photonics/Optics
Low-Excess-Noise, High-Gain Avalanche Photodiodes

Avalanche photodiodes (APDs) are widely used to sense and amplify optical signals into electric signals based on their high quantum efficiency of photon detection and desirable internal gain. The high internal gain associated with APDs, however, may also lead to increased levels of excess noise...

Briefs: Physical Sciences

The SWOT Science Simulator simulates projected SWOT altimetry observations that can be applied to an ocean general circulation model, allowing the exploration of ideas and methods to...

Briefs: Photonics/Optics

Every lens has an absolute upper performance limit dictated by the laws of physics. This limitation is controlled by the working f/# of the lens and the wavelength( s) of light that pass through the...

Briefs: Information Technology
Design and Construction of Protograph-Based LDPC Codes

Writing (recording) to a storage device and reading from it can be considered as a noisy channel. A storage device such as magnetic recoding and optical recording can be modeled as a partial response channel. Partial-response techniques are a special case of precoding technique where the...

Briefs: Sensors/Data Acquisition

Future cryogenic far-infrared (IR) missions will require moderate-resolution far-IR spectrometers operating at the photon background limit. Full utilization of these facilities requires...

Briefs: Test & Measurement
Optically Modulated Miniature Magnetometer

The optically modulated miniature magnetometer (OMMM) is intended to replace two separate instruments (each with their respective mass and power allotments) that are commonly needed together for scientific studies of magnetic fields — a triaxial fluxgate vector magnetometer and an optically pumped...

Briefs: Test & Measurement
Energy-Based Acoustic Measurement System for Rocket Noise

Development of the next generation of spaceflight vehicles has prompted a renewed focus on sound source characterization and near-field propagation modeling. Without advancements in these areas, large uncertainties in vibro-acoustic loading estimates on space vehicles and payloads may...

Briefs: Mechanical & Fluid Systems

A valve cage consists of a stackable planar structure design with paths that are azimuthally cut out and connected radially. The pattern causes the flow to move...

Briefs: Communications
Low-Noise Analog APDs with Impact Ionization Engineering and Negative Feedback

Silicon avalanche photodiodes (Si APDs) have low dark current and low excess noise factor, and are currently used in many of NASA’s missions. Noise equivalent power (NEP) of 40 to 50 fW/(Hz)1/2 over 140-MHz bandwidth has been demonstrated for Si APDs. Si...

Briefs: Sensors/Data Acquisition
Wide-Input-Range Signal-Conditioning Input Interface for Motor Position Sensing in Extreme Environments

Motor position sensing is a critical application in a number of systems. Galvanically isolated sensors for motor position sensing are strongly favored in both industrial and extreme-environment applications. Two examples of these sensors are...

Briefs: Sensors/Data Acquisition

A system has been developed using sound to detect problems on rovers or other remote platforms autonomously. It consists of a sensor array of microphones and...

Briefs: Mechanical & Fluid Systems
Elastic Deployable Composite Tubular Roll-Out Boom

The objective of this work was to develop an innovative deployable boom/structure technology that is ultra-lightweight (<30-grams/meter potential), and has extremely compact stowage volume (>100:1 compaction ratio), broad scalability (no size limits envisioned), high deployed frequency,...

Briefs: Electronics & Computers
Capacitively Coupled, High-Voltage Current Sensing for Extreme Environments

Wide-temperature and extreme-environment electronics are crucial to future missions. These missions will not have the weight and power budget for heavy harnesses and large, inefficient warm boxes. In addition, extreme-environment electronics, by their inherent nature,...

Briefs: Semiconductors & ICs
A Resistive, High-Voltage, Differential Input Interface in a 3.3-V BiCMOS 0.5-μm Process for Extreme Environments

Wide-temperature and extreme-environment electronics are crucial to future missions. These missions will not have the weight and power budget for heavy harnesses and large, inefficient warm boxes. In addition, extreme-environment...

Briefs: Sensors/Data Acquisition
Precision Current Input With Well-Defined Current Limiting for Extreme Environment Applications

Wide temperature and extreme environment electronics are crucial to future missions. These missions will not have the weight and power budget for heavy harnesses and large, inefficient warm boxes. In addition, extreme environment electronics, by their...

Briefs: Sensors/Data Acquisition
Magnetic Thermometer for High-Resolution 10-mK Scale Thermometry

A thin-film magnetic thermometer with integrated, superconducting quantum interference device (SQUID) readout has been designed for fast, precision temperature measurements in the 10-mK range. The compact magnetic thermometer consists of a miniature DC SQUID susceptometer with a...

Briefs: Information Technology

This hazard avoidance algorithm uses a single flash lidar range image to select a safe landing site for NASA missions. The advantage of flash lidar is that the entire range image is captured...

Briefs: Information Technology
Fast Classification Method for Multivariate Mixtures of Spectroscopic Responses

In many fields of spectroscopy, classification of the measured multivariate response is not always a straightforward process. Accurate classification is limited by many factors that are highly dependent upon the spectroscopy method being utilized. In all cases,...

Briefs: Aerospace
Flap Side Edge Liners for Airframe Noise Reduction

One of the more critical constraints to the continued growth of air traffic is the related concern regarding aircraft noise. This concern has resulted in increasingly stringent noise restrictions for airports, both nationally and internationally. One of the major stretch goals for NASA is to...

Briefs: Aerospace
Prediction of Visual Acuity from Wavefront Aberrations

Visual acuity (clearness of vision) usually is measured by an eye doctor using an eye chart. It measures the smallest letters that can be reliably identified by the patient at a specified distance. The traditional test requires the patient to look and report which letters they see.

Briefs: Manufacturing & Prototyping
Flap Edge Noise Reduction Fins

Aircraft noise is a significant problem with both economic and public health implications, especially for communities near airports. As a result, increasingly stringent constraints are being placed on aircraft carriers worldwide to reduce this noise. The current disclosure focuses on airframe noise generated at or...

Articles: Test & Measurement

Modern oscilloscopes come equipped with a host of different attributes, and many vendors tout their latest additions as “must have” features. With so many...

Briefs: Physical Sciences
Preparation, Planning, and Concept Demo of a Technique to Find ≈7-to-10-m Near Earth Asteroids

A paper describes a new technique designed to increase significantly the sensitivity for finding and tracking small, dim, and fast-moving near Earth asteroids (NEAs). The technique relies on a combined use of a novel data processing approach and a...

Briefs: Physical Sciences
Speech Acquisition and Automatic Speech Recognition for Integrated Spacesuit Audio Systems, Version II

Astronauts suffer from poor dexterity of their hands due to the clumsy spacesuit gloves during Extravehicular Activity (EVA) operations, and NASA has had a widely recognized but unmet need for novel human-machine interface technologies to...

Briefs: Physical Sciences
Optical Phased Array with Digitally Enhanced Interferometry

A proof-of-concept technique has been developed for measuring and controlling the individual phases of array elements. Electro-optic steering and beam-forming of laser beams is an emerging field with devices such as optical phased arrays that are capable of steering with significantly...

Briefs: Information Technology

The communication between NASA space mission operations teams and their respective spacecraft in outer space is accomplished via the Deep...

Briefs: Imaging
Reducing Drift in Stereo Visual Odometry

Visual odometry (VO) refers to the estimation of vehicle motion using onboard cameras. A common mode of operation utilizes stereovision to tri angulate a set of image features, track these over time, and infer vehicle motion by computing the apparent point cloud motion with respect to the cameras. It has...

Briefs: Imaging
Reducing Drift in Stereo Visual Odometry

Visual odometry (VO) refers to the estimation of vehicle motion using onboard cameras. A common mode of operation utilizes stereovision to tri angulate a set of image features, track these over time, and infer vehicle motion by computing the apparent point cloud motion with respect to the cameras. It has...

Briefs: Information Technology
Protograph-Based Raptor-Like Codes

Theoretical analysis has long indicated that feedback improves the error exponent but not the capacity of point-to-point memoryless channels. The analytic and empirical results indicate that at short blocklength regime, practical rate-compatible punctured convolutional (RCPC) codes achieve low latency with...