Special Coverage

Transducer-Actuator Systems for On-Machine Measurements and Automatic Part Alignment
Wide-Area Surveillance Using HD LWIR Uncooled Sensors
Heavy Lift Wing in Ground (WIG) Cargo Flying Boat
Technique Provides Security for Multi-Robot Systems
Bringing New Vision to Laser Material Processing Systems
NASA Tests Lasers’ Ability to Transmit Data from Space
Converting from Hydraulic Cylinders to Electric Actuators
Automating Optimization and Design Tasks Across Disciplines
Vibration Tables Shake Up Aerospace and Car Testing
Supercomputer Cooling System Uses Refrigerant to Replace Water

Wide-Band Radar for Measuring Thickness of Sea Ice

This instrument could contribute to understanding of climate change.

A wide-band penetrating radar system for measuring the thickness of sea ice is under development. The need for this or a similar system arises as follows: Spatial and temporal variations in the thickness of sea ice are important indicators of heat fluxes between the ocean and atmosphere and, hence, are important indicators of climate change in polar regions. A remote-sensing system that could directly measure the thickness of sea ice over a wide thickness range from aboard an aircraft or satellite would be of great scientific value. Obtaining thickness measurements over a wide region at weekly or monthly time intervals would contribute significantly to understanding of changes in the spatial distribution and of the mass balance of sea ice.

Posted in: Briefs, TSP, Electronics & Computers, Radar, Remote sensing, Radar, Remote sensing, Weather and climate

L-Band Transmit/Receive Module for Phase-Stable Array Antennas

A self-calibrating interferometric synthetic aperture radar instrument uses an electronically steerable radar antenna to achieve greater accuracy.

Interferometric synthetic aperture radar (InSAR) has been shown to provide very sensitive measurements of surface deformation and displacement on the order of 1 cm. Future systematic measurements of surface deformation will require this capability over very large areas (300 km) from space. To achieve these required accuracies, these spaceborne sensors must exhibit low temporal decorrelation and be temporally stable systems. An L-band (24-cm-wavelength) InSAR instrument using an electronically steerable radar antenna is suited to meet these needs. In order to achieve the 1-cm displacement accuracy, the phased array antenna requires phase-stable transmit/receive (T/R) modules. The T/R module operates at L-band (1.24 GHz) and has less than 1-deg absolute phase stability and less than 0.1-dB absolute amplitude stability over temperature. The T/R module is also high power (30 W) and power efficient (60-percent overall efficiency). The design is currently implemented using discrete components and surface mount technology.

Posted in: Briefs, TSP, Electronics & Computers, Antennas, Architecture, Radar, Sensors and actuators, Antennas, Architecture, Radar, Sensors and actuators

Microwave Power Combiner/Switch Utilizing a Faraday Rotator

Either or both of two input ports could be coupled to one output port.

A proposed device for combining or switching electromagnetic beams would have three ports, would not contain any moving parts, and would be switchable among three operating states:

Posted in: Briefs, Electronics & Computers

Compact Low-Loss Planar Magic-T

These wireless communications components are useful for base-station receivers, consumer electronics, and industrial microwave instrumentation.

This design allows broadband power combining with high isolation between the H port and E port, and achieves a lower insertion loss than any other broadband planar magic-T. Passive micro wave/millimeter-wave signal power is combined both in-phase and out-of-phase at the ports, with the phase error being less than ±1°, which is limited by port impedance.

Posted in: Briefs, Electronics & Computers, Architecture, Electrical systems, Architecture, Electrical systems

Next Generation Flight Controller Trainer System

The Next Generation Flight Controller Trainer (NGFCT) is a relatively inexpensive system of hardware and software that provides high- fidelity training for space-shuttle flight controllers. NGFCT provides simulations into which are integrated the behaviors of emulated space-shuttle vehicle onboard general-purpose computers (GPCs), mission-control center (MCC) displays, and space-shuttle systems as represented by high-fidelity shuttle mission simulator (SMS) mathematical models. The emulated GPC computers enable the execution of onboard binary flight-specific software. The SMS models include representations of system malfunctions that can be easily invoked. The NGFCT software has a flexible design that enables independent updating of its GPC, SMS, and MCC components.

Posted in: Briefs, Electronics & Computers, Computer simulation, Mathematical models, Flight control systems, Flight control systems, Reusable launch vehicles and shuttles

Quasi-Optical Transmission Line for 94-GHz Radar

This apparatus functions as a very-low-loss, three-port circulator.

A quasi-optical transmission line (QOTL) has been developed as a low-loss transmission line for a spaceborne cloud-observing radar instrument that operates at a nominal frequency of 94 GHz. This QOTL could also readily be redesigned for use in terrestrial millimeter- wave radar systems and millimeter-wave imaging systems.

Posted in: Briefs, Electronics & Computers, Communication protocols, Radar, Satellite communications, Communication protocols, Radar, Satellite communications

Using Pipelined XNOR Logic to Reduce SEU Risks in State Machines

Risk is reduced by use of fast state-machine and error-detection logic.

Single-event upsets (SEUs) pose great threats to avionic systems’ state machine control logic, which are frequently used to control sequence of events and to qualify protocols. The risks of SEUs manifest in two ways: (a) the state machine’s state information is changed, causing the state machine to unexpectedly transition to another state; (b) due to the asynchronous nature of SEU, the state machine’s state registers become metastable, consequently causing any combinational logic associated with the metastable registers to malfunction temporarily. Effect (a) can be mitigated with methods such as triple-modular redundancy (TMR). However, effect (b) cannot be eliminated and can degrade the effectiveness of any mitigation method of effect (a).

Posted in: Briefs, TSP, Electronics & Computers, Finite element analysis, Avionics, Avionics, Risk management

Vertical Isolation for Photodiodes in CMOS Imagers

Diffusion cross-talk would be reduced substantially.

In a proposed improvement in complementary metal oxide/semi con ductor (CMOS) image detectors, two additional implants in each pixel would effect vertical isolation between the metal oxide/ semiconductor field-effect transistors (MOSFETs) and the photodiode of the pixel. This improvement is expected to enable separate optimization of the designs of the photodiode and the MOSFETs so as to optimize their performances independently of each other. The purpose to be served by enabling this separate optimization is to eliminate or vastly reduce diffusion cross-talk, thereby increasing sensitivity, effective spatial resolution, and color fidelity while reducing noise.

Posted in: Briefs, Semiconductors & ICs, Imaging, Imaging and visualization, Imaging, Imaging and visualization

Converting From DDOR SASF to APF

A computer program called “ddor_sasf2apf” converts delta-door (delta differential one-way range) request from an SASF (spacecraft activity sequence file) format to an APF (apgen plan file) format for use in the Mars Reconnaissance Orbiter (MRO) mission-planning-and- sequencing process. The APF is used as an input to “APGEN/AUTOGEN” in the MRO activity- planning and command-sequence-generating process to sequence the delta-door (DDOR) activity. The DDOR activity is a spacecraft tracking technique for determining spacecraft location.

Posted in: Briefs, Information Sciences, Communication protocols, Computer software / hardware, Computer software and hardware, Surveillance, Communication protocols, Computer software / hardware, Computer software and hardware, Surveillance, Spacecraft

Converting From CVF to AAF

A computer program called “dsn config converter” automates what had been a manual process for updating the multi-mission adaptation file (multi.aaf) used by a multiple- mission- command- sequence- generating process comprised of a combination of the AUTOGEN and APGEN programs mentioned in the immediately preceding article. The program converts the dsn_config.cvf file that provides DSN (Deep Space Network) antenna configuration code mappings from a context variable file (CVF) format used in another part of the command generation process to an APGEN activity file (AAF) format used by AUTOGEN and APGEN.

Posted in: Briefs, Information Sciences, Communication protocols, Computer software / hardware, Computer software and hardware, Flight management systems, Communication protocols, Computer software / hardware, Computer software and hardware, Flight management systems, Automation

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