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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Digital filtering of random digits

Digital simulation of linear filter, investigating noise and rounding errors effects on decoding signals from lunar and interplanetary probes

Jennings, G.↗
NASA NTRS1973

Digital hardware and computer system for a digital image recorder.

Description of the digital memory and related computer system used at the Palomar Mountain Observatory. The memory was designed to have a large number of pixels, a high capacity for each pixel, and fast access for use with a variety of image sensors. As an image integration and storage device, this memory is shown to possess ideal properties, namely, it is strictly linear, has a wide dynamic range, and the image does not deteriorate with time. The observer has a visual display which enables him to monitor the image as it is being integrated.-

Dennison, E. W.↗
NASA NTRS1974

Digital system identification and its application to digital flight control

On-line system identification of linear discrete systems for implementation in a digital adaptive flight controller is considered by the conventional extended Kalman filter and a decoupling process in which the linear state estimation problem and the linear parameter identification problem are each treated separately and alternately. Input requirements for parameter identifiability are established using the standard conditions of observability for a time variant system. Experimental results for simulated linearized lateral aircraft motion are included along with the effect of different initialization and updating procedures for the priming trajectory used by the filter.

Kotob, S.↗
NASA NTRS1979

Digital systems design language. Design synthesis of digital systems

The Digital Systems Design Language (DDL) is implemented on the SEL-32 computer systems. The details of the language, translator and simulator programs are included. Several example descriptions and a tutorial on hardware description languages are provided, to guide the user.

Shiva, S. G.↗
NASA NTRS1985

Digital Filters for Digital Phase-locked Loops

An s/z hybrid model for a general phase locked loop is proposed. The impact of the loop filter on the stability, gain margin, noise equivalent bandwidth, steady state error and time response is investigated. A specific digital filter is selected which maximizes the overall gain margin of the loop. This filter can have any desired number of integrators. Three integrators are sufficient in order to track a phase jerk with zero steady state error at loop update instants. This filter has one zero near z = 1.0 for each integrator. The total number of poles of the filter is equal to the number of integrators plus two.

Simon, M.↗
NASA NTRS1989

Digital imaging technology assessment: Digital document storage project

An ongoing technical assessment and requirements definition project is examining the potential role of digital imaging technology at NASA's STI facility. The focus is on the basic components of imaging technology in today's marketplace as well as the components anticipated in the near future. Presented is a requirement specification for a prototype project, an initial examination of current image processing at the STI facility, and an initial summary of image processing projects at other sites. Operational imaging systems incorporate scanners, optical storage, high resolution monitors, processing nodes, magnetic storage, jukeboxes, specialized boards, optical character recognition gear, pixel addressable printers, communications, and complex software processes.

Source record↗
NASA NTRS1978

A study of digital holographic filters generation. Phase 2: Digital data communication system, volume 1

An empirical study of the performance of the Viterbi decoders in bursty channels was carried out and an improved algebraic decoder for nonsystematic codes was developed. The hybrid algorithm was simulated for the (2,1), k = 7 code on a computer using 20 channels having various error statistics, ranging from pure random error to pure bursty channels. The hybrid system outperformed both the algebraic and the Viterbi decoders in every case, except the 1% random error channel where the Viterbi decoder had one bit less decoding error.

Ingels, F. M.↗