Achieving Embedded Software Safety with Agility

Safety-critical development standards, such as DO-1781, have been very successful in guiding the production of reliable software. These standards assist developers in applying good software practices during development, ensuring, as much as possible, the absence of errors. Compliance with these stringent standards involves a high cost because of their labor-intensiveness and high levels of know-how.

Posted in: Articles, Articles, Electronics & Computers

Optimizing the Interoperability of Military Satellite Communications

Satellite communications offer mobility and communications for military operations in remote locations where terrestrial-based connectivity is not available, or is too expensive. Unfortunately, satellite connectivity brings many challenges that can impair network performance in delivering mission-critical information and applications. High-latency transport and application protocol inefficiencies, adverse weather, and interference are just a few of the causes that slow the delivery of applications and limit the amount of traffic that can run over a satellite link. Compounding these problems is interoperability among disparate military networks that can jeopardize mission-critical communications.

Posted in: Application Briefs, Application Briefs, Electronics & Computers, Optimization, Communication protocols, Satellite communications, Defense industry, Satellites

Choosing Your RF Design Environment Flow

You can’t build a house without blueprints. So why do so many RF design flows try to build a board without a schematic? Most often, this crude process comes about due to lack of availability of RF design tools. But the wireless industry is the new cool kid on the block. As a result, electronic design automation (EDA) software vendors are scrambling to disencumber the rigid printed circuit board (PCB) world of tailored processes and streamlined user flows. RF engineers demand freedom from constraints, so EDA vendors are peeling back the layers of traditional PCB design and opening up some truly excellent solutions. But with these solutions, RF engineers are challenged to rethink their request for primitive simplicity and consider a higher-level process.

Posted in: Articles, RFM Catchall, Aerospace, Design processes, Architecture, Computer software / hardware, Wireless communication systems, Product development, Systems engineering

Through-the-Wall Small Weapon Detection Based on Polarimetric Radar Techniques

Detecting concealed small weapons carried by people has received significant interest from law enforcement agencies as well as the military, most frequently for application in controlling checkpoints (in airports, border crossings, public spaces, etc.). Imaging systems for concealed weapons based on radar or other sensor technologies have been recently developed and tested. Most of the existing electromagnetic (EM) sensors suitable for this application operate at very high frequencies, usually in the millimeter or terahertz frequency bands and produce high-resolution images. Although these EM waves can penetrate through clothing (textile materials), they have very poor penetration properties through many common construction materials (such as brick or concrete). Most through-the-wall radars must operate at much lower frequencies, usually below 4 GHz, in order to “see” targets behind walls. However, at those low frequencies, the image resolution is degraded, so small weapons carried by humans may be difficult to detect directly in the image domain.

Posted in: Briefs, Physical Sciences, Imaging, Radar, Security systems, Sensors and actuators

Designing a Sensorless Torque Estimator for Direct Torque Control of an Induction Motor

Induction motors often are the preferred choice among industrial motors due to the modern power electronics that improve their speed control. Vitally important for the speed control of a motor is the accurate estimation of the magnetic flux and the electromagnetic torque. Knowing the electromagnetic torque of a motor, one is able to control it and thus monitor the speed faster and more stably.

Posted in: Briefs, Mechanical Components, Measurements, Power electronics, Industrial vehicles and equipment

A Bistable Microelectronic Circuit for Sensing an Extremely Low Electric Field

Bistable systems are prevalently found in many sensor systems. It is well established that a well-designed coupling scheme, together with an appropriate choice of initial conditions, can induce oscillations (i.e. periodic switching between stable fixed points) in over-damped bistable dynamical systems when a control parameter exceeds a threshold value. This behavior was demonstrated in a specific prototype system comprised of three unidirectionally coupled ferromagnetic cores, the basis of a coupled core fluxgate magnetometer. Another prototypical (quartic potential based) system of coupled over-damped Duffing elements has been applied to describe the dynamics of the polarization inside a ferroelectric material, the basis of an electric-field sensor currently under development.

Posted in: Briefs, Electronics & Computers, Architecture, Microelectricmechanical device, Sensors and actuators, Electric power, Product development

Fiber-Optic Seismic Sensor for Unattended Ground Sensing

Seismic military sensors are required to be robust, reliable, compact, and easy to install and operate to be effective in the battlefield environment. Three types of sensor technologies were addressed that provide improved design and novel signal processing techniques: (a) a wavelength scanning, pulsed-laser-based demodulation system; (b) digital lock-in amplifier and field-programmable gate array (techniques) for weak signal detection and processing; and (c) improved seismic sensitivity based on carbon fiber optic composite cantilever and fiber-Bragg-grating (FBG).

Posted in: Briefs, Physical Sciences, Fiber optics, Sensors and actuators, Defense industry

Reflected Signal Analysis

Forensic characterization of a wireless device is useful in many applications. An example of this is in the testing of Federal Communications Commission (FCC) Part 15 devices that must adhere to strict guidelines with regard to RF interference; one reason being problems with Portable Electronic Devices (PEDs) carried onboard aircraft. The operation of PEDs aboard U.S.-registered civil aircraft is limited. These rules also permit the use of specific PEDs after the aircraft operator has determined that the PED will not interfere with the operations of the aircraft. However, how can the aircraft operator know which PEDs are approved, or if the approved devices are being operated at inappropriate times? Compliance can be verified by detecting the operation of transmitting PEDs (T-PEDs) using an onboard monitoring system, or it could be verified by characterizing the device at a gate entry point, whether powered on or off, using specially designed probe signals and forensic techniques to classify the returned signal. In a more general setting, forensic characterization allows determination of the type of device, make, model, configuration, and other characteristics based on observation of the data that the device produces. The unique characteristics of the device are known as device signatures or device fingerprints.

Posted in: Briefs, Electronics & Computers, Electromagnetic compatibility, Wireless communication systems, Aircraft operations, Regulations, Identification

Threshold Voltage Tuning of Metal-Gate MOSFETs Using an Excimer Laser

This work presents a localized method for tuning the threshold voltages (Vt) of multilayer metal-gate metal-oxide-semiconductor field-effect transistor (MOSFET) devices with a spatial area theoretically limited by the wavelength of the laser beam. This technique allows an independent means to tailor threshold voltage on a device-to-device basis that provides greater design flexibility. This maskless technique allows tailoring of thresholds by tuning the work function of the gate by intermixing titanium and titanium nitride using a laser pulse. The source and drains of the MOSFET are simultaneously annealed by the laser.

Posted in: Briefs, Photonics, Calibration, Lasers, Semiconductor devices, Transistors, Titanium

Development of GaN-Based Nanostructure Photon Emitters

Gallium nitride (GaN)-based wide bandgap semiconductors are very important material systems for fabrication of photon emitters in a wide range of wavelengths. In particular, the light emitters in ultraviolet (UV), blue, and green wavelengths have been developed and demonstrated in recent years. Besides these UV and visible light emitters, the unique properties of a GaN material system such as large exciton energy and large LO phonon energy, have been proposed as a very suitable material candidate for realization of various photon emitters such as single-photon emitters, LEDs, vertical cavity surface emitting lasers (VCSELs), and quantum cascade lasers (QCL) at room temperature.

Posted in: Briefs, Photonics, Lasers, Fabrication, Materials properties, Semiconductors