A synchronised Direct Digital Synthesiser

We describe a Direct Digital Synthesiser (DDS) which provides three frequency-locked synchronised outputs to generate frequencies from DC to 160 MHz. Primarily designed for use in a heterodyning range imaging system, the flexibility of the design allows its use in a number of other applications which require any number of stable, synchronised high frequency outputs. Frequency tuning of 32 bit length provides 0.1 Hz resolution when operating at the maximum clock rate of 400 MSPS, while 14 bit phase tuning provides 0.4 mrad resolution. The DDS technique provides very high relative accuracy between outputs, while the onboard oscillator’s stability of ±1 ppm adds absolute accuracy to the design

Expanded study of feasibility of measuring in-flight 747/JT9D loads, performance, clearance, and thermal data

The JT9D jet engine exhibits a TSFC loss of about 1 percent in the initial 50 flight cycles of a new engine. These early losses are caused by seal-wear induced opening of running clearances in the engine gas path. The causes of this seal wear have been identified as flight induced loads which deflect the engine cases and rotors, causing the rotating blades to rub against the seal surfaces, producing permanent clearance changes. The real level of flight loads encountered during airplane acceptance testing and revenue service and the engine's response in the dynamic flight environment were investigated. The feasibility of direct measurement of these flight loads and their effects by concurrent measurement of 747/JT9D propulsion system aerodynamic and inertia loads and the critical engine clearance and performance changes during 747 flight and ground operations was evaluated. A number of technical options were examined in relation to the total estimated program cost to facilitate selection of the most cost effective option. It is concluded that a flight test program meeting the overall objective of determining the levels of aerodynamic and inertia load levels to which the engine is exposed during the initial flight acceptance test and normal flight maneuvers is feasible and desirable. A specific recommended flight test program, based on the evaluation of cost effectiveness, is defined

A 12 GHz satellite video receiver: Low noise, low cost prototype model for TV reception from broadcast satellites

A 12-channel synchronous phase lock video receiver consisting of an outdoor downconverter unit and an indoor demodulator unit was developed to provide both low noise performance and low cost in production quantities of 1000 units. The prototype receiver can be mass produced at a cost under $1540 without sacrificing system performance. The receiver also has the capability of selecting any of the twelve assigned satellite broadcast channels in the frequency range 11.7 to 12.2 GHz

Development of a portable low-cost digital shearography system

Includes summary.Includes bibliographical references (leaves 138-142).Shearography is an optical non-destructive testing technique that is well-suited, but not limited, to testing composite materials. The method takes advantage of the special properties of lasers, namely their high coherence length and monochromatic light, to detect flaws such as cracks, debonds and delaminations in materials

Remote experimental station for engineering education

This thesis provides a distance-learning laboratory for students of electrical and computer engineering department where the instructor can conduct experiments on a computer and send the results to the students at remote computers. The output of the experiment conducted by the instructor is sampled using a successive approximation Analog to Digital (A/D) converter. A microcontroller collects samples using high speed queued serial peripheral interface clock and transmits data to IBM-compatible personal computer over a serial port interface, where the samples are processed using Fast Fourier Transforms and graphed. The client/server application developed transfers the acquired samples over Transmission Control Protocol/Internet Protocol (TCP/IP) network with operational Graphical User Interface (GUI) to the remote computers where the samples are processed and presented to students. The application was tested on all Windows platforms and various Internet speeds (56k modem, Digital Subscriber Line (DSL), Local Area Network (LAN)). The results were analyzed and appropriate methodology of Remote Experimental Station was formulated

What characteristics a clinical CSF system has to have?

We discuss the characteristics a system to measure the contrast sensitivity function (CSF) in the ophthalmologic clinic has to have. We propose that this system should be computer based in order to assure flexibility and precision. Besides the original calibration, this equipment needs an auxiliary system to keep the working conditions allowing periodical gamma corrections. We try a calibration method based on visual comparisons and show that it is valid and simple. We propose to use an adaptive psychophysical method to obtain contrast thresholds that assure a good compromise between precision and duration of the whole test. Finally, we propose that the system has to have its own normality curves for the different age ranges allowing the practitioner to perform clinical evaluations. Summing up, we can say that taking into account the above issues, the fidelity of the stimuli will be guaranteed and the challenges entailed in its transference to the clinic will be overcome.Fil: Colombo, Elisa Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Luminotecnia, Luz y Visión; ArgentinaFil: Issolio, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Luminotecnia, Luz y Visión; ArgentinaFil: Santillán, Javier Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Luminotecnia, Luz y Visión; ArgentinaFil: Rolando Aguirre. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; Argentin

Rocket Cam: Low Frequency Analog Transmission of Digital Video

The camera module provides data for improving models of dynamic events on Orbital ATK Corp. rockets and aids in troubleshooting, if necessary. Video images provide a valuable addition to the strain, vibration, shock, and acoustic data used for modeling dynamic events, such as stage separations. The cameras can record a duration of video data suitable for capturing a dynamic event and of high enough quality to aid in its modeling. The module readily integrates into the rocket’s current analog data collection systems. The project has further relevance to any other application that necessitates video data transmission over similar limited-bandwidth, analog data channels. Though errorless data transmission was not achieve, over 99% of the digital by bytes transmitted where recovered to within 99% accuracy. This level of error is not suitable for compressed data. However, the primary sources of error can potentially be resolved by adaption to a more permanent prototype platform

Design and implementation of real-time seamless display

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1999.Includes bibliographical references (p. 49).by Ivan Gonzalez-Gallo.M.Eng