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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 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Experience gained from computer processing of physical experimental data during the restoration of measured values

The processing stage in which the restored values of the physical parameters are received is described. The following main steps are discussed: estimation of the state of the telemetry data, processing of the calibration data, and determination of the errors in the data; data decommutation and analysis of the structure of measurement cycles for each instrument; decoding, estimates of the reliability of the restored data, and their agreement with the models adopted for the measurement process; and analysis of errors due to deterministic and random factors. A block diagram of the method is presented.

Mamotko, Z. N.↗
NASA NTRS1975

System consideration, design approach and test of a low gain spherical coverage antenna for large space vehicles

A fixed beam array antenna approach is proposed to meet the omnidirectional receiving and transmitting requirements of LST (Large Space Telescope). The proposed method uses an antenna of known performance and scales the size and frequency to conform with the LST 1/5-th scale model. The simplification that the approach provides over switching antenna elements on board the LST or switching from the ground by frequency diversity makes it worthy of consideration against the factors of performance, cost, reliability, and operations complexity. For LST applications, the system capabilities, requirements, and margins are summarized. The areas to be covered by further investigations into the proposed LST antenna are noted.

Ferguson, R. E.↗
NASA NTRS1977

X-band antenna gain and system noise temperature of 64-meter deep space stations

A set of measured data on the X-band performance of the three 64-meter deep space stations was obtained for use in future mission telecommunication design and predictions. The test configuration and measurement procedure is described. A method of modelling attenuation due to the atmosphere is given. Radio source brightness temperature and flux density are reviewed.

Benjauthrit, B.↗
NASA NTRS1978

Digital automatic gain amplifier

A circuit is described for adjusting the amplitude of a reference signal to a predetermined level so as to permit subsequent data signals to be interpreted correctly. The circuit includes an operational amplifier having a feedback circuit connected between an output terminal and an input terminal; a bank of relays operably connected to a plurality of resistors; and a comparator comparing an output voltage of the amplifier with a reference voltage and generating a compared signal responsive thereto. Means is provided for selectively energizing the relays according to the compared signal from the comparator until the output signal from the amplifier equals to the reference signal. A second comparator is provided for comparing the output of the amplifier with a second voltage source so as to illuminate a lamp when the output signal from the amplifier exceeds the second voltage.

Holley, L. D.↗
NASA NTRS1979

Filtering technique based on high-frequency plant modeling for high-gain control

This invention was an improvement in aircraft control systems that utilized feedback motion sensors to generate a signal to control the aircraft. The improvement consisted essentially of a complementary filter comprising a simplified model of the aircraft, a high pass filter, a low pass filter and a summing amplifier. The control signal was applied to the simplified model of the aircraft which attempted to compute the vehicle response to the signal. This computed response was then fed into the high pass filter to eliminate long term errors in the calculated response, with the result that a good estimate of the high frequency content of the aircraft motion was obtained. In order to obtain a good estimate of the low frequency content of the motion, a rate gyro signal was fed through the low pass filter that eliminates all of the offending noise.

Niessen, F. R.↗
NASA NTRS1979

Opportunities for supersonic performance gains through non-linear aerodynamics

This paper contains a number of examples wherein basic aerodynamic shapes are shown to achieve improved performance when non-linear effects are taken into account. Analytical, numerical, and experimental results have all been used to demonstrate this conclusion. Improvements in both zero lift drag and drag due to lift have been identified. The results show that the exploitation of these non-linear aerodynamic effects may be a key ingredient of future supersonic aircraft.

Mason, W. H.↗
NASA NTRS1979

A 4-W 56-dB gain microstrip amplifier at 15 GHz utilizing GaAs FET's and IMPATT diodes

Performance results and design considerations are presented for an all solid-state Ku-band power amplifier which is feasible for use in PM communication systems for airborne or spacecraft transmitter applications. A six-stage GaAs FET preamplifier and a driver and balanced power amplifier utilizing GaAs IMPATT diodes operating in the injection locked oscillator mode are discussed. For high power and efficiency Schottky-Read IMPATT's with low-high-low doping profiles are employed. For improved reliability the IMPATT's incorporate a TiW barrier metallization to retard degradation of the IMPATT's. Results of accelerated life testing of the IMPATT devices are also presented.

Sokolov, V.↗
NASA NTRS1980

Experience with an adaptive stick-gain algorithm to reduce pilot-induced-oscillation tendencies

As part of a program to improve the approach and landing characteristics of the Space Shuttle, the NASA Dryden Flight Research Center has developed an adaptive algorithm that varies the longitudinal stick gearing to reduce the Shuttle's tendency for pilot-induced oscillation (PIO). This paper describes the algorithm, which is known as the PIO suppressor, and discusses some of the tradeoffs involved in optimizing the system. The results of fixed-base, moving-base, and in-flight simulations of the PIO suppressor are presented.

Powers, B. G.↗
NASA NTRS1983

The effect of partial coherence in receiving system noise temperature on array gain for telemetry and radio frequency carrier reception for receiving systems with unequal predetection signal-to-noise ratios

Signal to noise ratio improvement realized by arraying receiving systems or stations for coherent reception is reduced when some portion of the predetection noise is coherent in the array. This effect for arrayed receiving systems with unequal apertures including expected performance for selected planets of the solar system within the array beamwidth is examined.

Brockman, M. H.↗