Passive Devices Designed to Improve Signal-to-Noise Ratios in Defense Electronics

While power architectures of defense electronics are extremely diverse, all have common operational demands: they must be robust (shock, vibration, temperature extremes), highly reliable, able to power-up after periods of dormancy, and be based on components with minimal obsolescence. Design engineers can improve their power distribution quality over a wide spectrum of signal types from digital to RF power, while meeting the above application requirements, through the implementation of various passive components designed specifically to enhance performance and improve signal-to-noise ratios. In this article we will talk about low-inductance, low-ESR power filter capacitors; wet tantalum capacitors; RF/microwave directional couplers; and land grid array inductors and filters.

Posted in: Articles, RFM Catchall, Aerospace, Optimization, Capacitors, Power electronics, Defense industry

Reliable EMI Shielding Materials and RF Cable Assemblies Ensure High Performance for Handheld Test Instruments

While high-performance test equipment has been used successfully in the laboratory for many years, the trend is moving toward remote testing, which means smaller, lightweight equipment that can be taken into the field. It is crucial that field equipment delivers results with the same quality as those generated in the laboratory environment. Therefore, signal integrity, durability, and long-term reliability of the instrument and its accessories are key factors in ensuring consistent, accurate, and repeatable measurements. Whether you are an instrument designer or a field engineer, you need to consider two components that can directly affect the overall performance of handheld instruments — EMI shielding and long-term cable reliability.

Posted in: Articles, RFM Catchall, Aerospace, Downsizing, Electromagnetic compatibility, Electronic equipment, Lightweighting

Forehead-Mounted Sensor Measures Oxygen Saturation for Hypoxia Early Detection and Warning

Symptoms of hypoxia – a deficiency in the amount of oxygen reaching body tissues - have been documented among rotary-wing pilots and aircrew flying at altitudes as low as 8,000 feet. Effective hypoxia-related mishap prevention relies upon rapid recognition of hypoxia symptoms and expeditious execution of emergency procedures. This is particularly challenging in rotary wing aircraft, where the lack of adequate training makes reliance on hypoxia self-detection an ineffective solution. An automated warning would be preferable, but currently no military aviation platform is outfitted with a physiological monitoring system to alert pilots and aircrew of impending hypoxic episodes.

Posted in: Briefs, Physical Sciences, Measurements, Sensors and actuators, Medical, health, and wellness, Personnel, Oxygen

Manifold-Based Image Understanding

The rapid growth of sensing and imaging technology, combined with the need for near-real-time action based on the sensed data, has rendered automatic processing, understanding, and decision-making vital to our national security. A unified theory and practical toolset was developed for the analysis and processing of signal and image manifolds for signal and image understanding purposes. The unifying theme is the multiscale geometric structure of signal and image families and manifolds. Specifically, theory and tools were developed for (1) model-based signal and image recognition and registration, (2) sensing and compressing data on manifolds, and (3) data-driven manifold modeling and learning.

Posted in: Briefs, Physical Sciences, Mathematical models, Imaging, Security systems, Data management

Flexible Computing Architecture for Real-Time Skin Detection

In both the Air Force and search and rescue (SAR) communities, there is a need to detect and characterize persons. Existing methods use red-green-blue (RGB) imagery, but produce high false alarm rates. New technology in multispectral skin detection is better than the existing RGB methods, but lacks a control and processing architecture to make them efficient for real-time problems. A number of applications require accurate detection and characterization of persons, human measurement and signature intelligence (H-MASINT), and SAR in particular. H-MASINT requires it for the detection of persons in images so other processing can be performed. It is useful in the SAR community as a method of finding persons partly obscured, in remote regions, and either living or deceased.

Posted in: Briefs, Information Technology, Architecture, Imaging, Surveillance, Personnel, Rescue and emergency vehicles and equipment

Battery Electrolyte Level Detector Apparatus

An apparatus has been developed for checking the electrolyte level in a battery, providing a safer and more efficient means to do so. The result is a non-intrusive apparatus and method of checking the electrolyte level that reduces the need to open the caps on the battery by checking the level externally.

Posted in: Briefs, Physical Sciences, Batteries, Sensors and actuators, Electrolytes

Magnetic Random Access Memory Integrated Passive Components

An embedded magnetic memory technology was developed to be integrated into a Complementary Metal Oxide Semiconductor (CMOS) circuit fabrication process to provide radiation-hard logic elements and small random access memories. The goal was not to provide large scale, bulk memory, but latches and flip-flops that serve as state and data registers for sequential logic, and configuration registers for configurable logic. The benefits include the ability to power down a subsystem while retaining system state, thus saving energy until the subsystem is required. The subsystem can then be powered up and begin operating in milliseconds.

Posted in: Briefs, Electronics & Computers, Computer software / hardware, Semiconductor devices, Fabrication

Differential Amplifier Circuits Based on Carbon Nanotube Field Effect Transistors (CNTFETs)

Since their discovery, carbon nanotubes (CNTs) have been extensively studied for their great potential in a variety of applications. Several desirable properties that CNTs possess include a high thermal conductivity, high electrical mobility, high electrical current capacity, high tensile strength, small size, compatibility with current semiconductor fabrication processes, and ability to be functionalized.

Posted in: Briefs, Electronics & Computers, Amplifiers, Transistors, Fabrication, Nanotechnology

AlInGaN Bandgap and Doping Engineering for Visible Laser Diodes

There is a great need to develop chip-scale visible lasers for many applications, including laser sight, environmental monitoring, and compact pumping sources for ultra-short laser pulse generation, high-luminous full-color displays, new-generation solid-state lighting, etc. The realization of chip-scale visible laser diodes (LDs) would provide significant benefits in terms of cost, volume, and the ability of photonic integration with other functional devices. Significant progress in nitride material technology has been achieved, and high-performance visible LEDs and near-UV LDs based on InGaN are now commercially available.

Posted in: Briefs, Photonics, Integrated circuits, Lasers, Materials properties

Photorefractive Polymers for Updatable 3D Displays

Photorefractive (PR) polymer composites developed for 3D display applications contain a copolymer as the hole-transporting host matrix. The copolymer approach is followed to reduce the phase separation typical in guest-host polymer systems with low glass transition temperature (Tg), thus allowing increased loading of functional components such as NLO chromophores. The copolymer consists of a polyacrylate backbone with pendant groups tetraphenyldiaminobiphenyltype (TPD) and carbaldehyde aniline (CAAN) attached through an alkoxy linker (PATPD-CAAN). A fluorinated dicyanostyrene (FDCST) NLO chromophore was added to provide sufficient refractive index change and charge generation at the wavelength of interest (532 nm). The plasticizer Nethyl carbazole (ECZ) was also used to reduce the Tg to room temperature. In some composites, a fullerene derivative [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) was used to provide improved sensitization.

Posted in: Briefs, Photonics, Displays, Composite materials, Polymers