ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • General Chemistry  (921)
  • Physics  (480)
  • COMMUNICATIONS
  • Cell & Developmental Biology
  • 1970-1974  (1,830)
  • 1973  (1,830)
Collection
Keywords
Publisher
Years
  • 1970-1974  (1,830)
Year
  • 1
    facet.materialart.
    Unknown
    Television experiment (1973)
    In:  CASI
    Details
    Publication Date: 2005-11-30
    Description: The fixed and variable Martian features investigated by the TV experiment on Mariner 9 are described. Articles are presented concerning the dust storm of October to November over the Southern Hemisphere; global surface geodesy and cartography; geology; and the satellite astronomy.
    Keywords: COMMUNICATIONS
    Type: Mariner Mars 1971 Proj., Vol. 5; p 63-70
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 2
    facet.materialart.
    Unknown
    Structure of proton centers and associated nonthermal bursts at microwave frequencies (1973)
    In:  CASI
    Details
    Publication Date: 2006-04-05
    Description: A very broad band of electromagnetic radiation is emitted during solar flares, especially at the explosive phase. The existence of a large variety of plasmas with various densities and a wide range of temperatures or energies is proposed as the initiating agent. The manner in which the plasmas are heated and accelerated to subrelativistic and relativistic energies is discussed. Observational evidence on the characteristics of active regions which produced proton flares and on the structure of the associated nonthermal microwave bursts of the sun is presented. The behavior of subrelativistic electrons on the sun is described.
    Keywords: COMMUNICATIONS
    Type: NASA, Washington High Energy Phenomena on the Sun; p 78-86
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 3
    facet.materialart.
    Unknown
    Vibration resistance of the wire-feed mechanism of a magnetic recording apparatus (1973)
    In:  CASI
    Details
    Publication Date: 2006-03-28
    Description: The effects of external mechanical and climatic actions on the efficient operation of magnetic tape recording equipment are analyzed. The efficiency and reliability of the recording system are determined by the structural parameters and the characteristics of the individual elements of the transport mechanism circuit. The resistance of tape recording equipment to the effects of vibration is considered essential for reliable operations. Methods for insuring reliable tape transport and recording action are discussed.
    Keywords: COMMUNICATIONS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 271-274
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 4
    facet.materialart.
    Unknown
    Measurement of irregularities in angular velocities of rotating assemblies in memory devices on magnetic carriers (1973)
    In:  CASI
    Details
    Publication Date: 2006-03-28
    Description: Problems in measurement of irregularities in angular velocity of rotating assemblies in memory devices with rigid and flexible magnetic data carriers are discussed. A device and method for determination of change in angular velocities in various frequency and rotation rate ranges are examined. A schematic diagram of a photoelectric sensor for recording the signal pulses is provided. Mathematical models are developed to show the amount of error which can result from misalignment of the test equipment.
    Keywords: COMMUNICATIONS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 279-282
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 5
    facet.materialart.
    Unknown
    A high resolution study in time, position, intensity, and frequency of a radio event on 14 January 1971 (1973)
    In:  CASI
    Details
    Publication Date: 2006-04-05
    Description: High resolution position and spectrum measurements were made of a complex solar radio activity on January 14, 1971, from 1120 to 1130 UT. Positions were measured with 169 MHz Nancay E-W Radioheliograph, while dynamic spectra and polarization were observed with the 60-channel radiospectrograph of Nera. The radio event consisted of two closely similar groups of type 3 bursts and type 2-like details, and a stationary type 4 continuum, including some very clear pulsating structures. The general aspect of this activity is presented.
    Keywords: COMMUNICATIONS
    Type: NASA, Washington High Energy Phenomena on the Sun; p 610-614
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 6
    facet.materialart.
    Unknown
    Solar millimeter bursts (1973)
    In:  CASI
    Details
    Publication Date: 2006-04-05
    Description: Solar burst observations in the region above 10 GHz (wavelengths less than 3 cm.) are discussed. Observations have shown that many major solar events have large millimeter wave components. The total burst radio energy is frequently concentrated in this part of the spectrum. Graphs are presented showing the peak flux density spectrum for bursts on specific dates. Microwave burst mean duration is plotted as a function of the particle energy.
    Keywords: COMMUNICATIONS
    Type: NASA, Washington High Energy Phenomena on the Sun; p 114-123
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 7
    facet.materialart.
    Unknown
    Comparison between photogrammetric and bistatic-radar slope frequency distributions (1973)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: A comparison was made of the results for lunar surface roughness estimates and slope frequency distributions obtained by using photogrammetric techniques with those obtained by using bistatic radar. Three topics were discussed: (1) the form of the slope frequency distributions, (2) the change of roughness estimates of the lunar surface with scale, and (3) the magnitude of surface roughness.
    Keywords: COMMUNICATIONS
    Type: NASA. Johnson Space Center Apollo 17 Prelim. Sci. Rept.; 9 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 8
    facet.materialart.
    Unknown
    Calibration of radar data from Apollo 17 and other mission results (1973)
    In:  CASI
    Details
    Publication Date: 2006-01-11
    Description: An examination was made of radar data on depolarized radar echoes for the general areas of (1) the Apollo 11, 12, 14, 15, 16, and 17 landing sites, (2) Ranger 7, 8, and 9 impact sites, and (3) the Surveyor 1, 3, 5, and 7 landing sites. These data were then compared with photographic data. Surveyor 6 was excluded because it landed near the center of the lunar disk where echo data are poor. Three problems concerning the echo data are (1) the frequency distributions of echo strengths from site to site, (2) the areal distribution of echoes, and (3) detailed correlation of echoes with the photographs of the Apollo 17 landing area.
    Keywords: COMMUNICATIONS
    Type: NASA. Johnson Space Center Apollo 17 Prelim. Sci. Rept.; 7 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 9
    facet.materialart.
    Unknown
    High sensitivity spectral observations in the decametric range (1973)
    In:  CASI
    Details
    Publication Date: 2006-04-05
    Description: High resolution dynamic spectra of solar emissions in the range 80 to 20 MHz are discussed. The major features of observations described are (1) decametric storms, (2) type 3 bursts, and (3) time profile of type 3 bursts.
    Keywords: COMMUNICATIONS
    Type: NASA, Washington High Energy Phenomena on the Sun; p 602-609
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 10
    facet.materialart.
    Unknown
    Solar radio bursts at kilometer wavelengths (1973)
    In:  CASI
    Details
    Publication Date: 2006-04-05
    Description: The potential value of traveling solar radio bursts for investigating energetic particle propagation, and for probing the interplanetary medium is discussed. A general survey of the characteristics of type 3 radio phenomena observed at hectometer and kilometer wavelengths is presented along with a brief discussion of the relationships among type 1 meter noise storms, decametric continuum, and type 3 hectometric storms. Type 3 bursts are analyzed to show how these data provide information about the average energy, dispersion, and trajectory of energetic particles, the interplanetary scale, and magnetic field configuration. The recent observations of type 2 shock wave phenomena at kilometer wavelengths are described, and current research and the direction of future observation are outlined.
    Keywords: COMMUNICATIONS
    Type: High Energy Phenomena on the Sun; p 519-536
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 11
    facet.materialart.
    Unknown
    A method of diagnostics of the dynamic stability of the carrier in a magnetic recording playback circuit (1973)
    In:  CASI
    Details
    Publication Date: 2006-03-28
    Description: Graphical plotting of the dynamic instability is used to diagnose carrier behavior according to a given carrier tension fluctuation spectrum.
    Keywords: COMMUNICATIONS
    Type: Cybernetic Diagnostics of Mech. Systems with Vibro-acoustic Phenomena (NASA-TT-F-14899); p 107-109
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 12
    facet.materialart.
    Unknown
    Verification of performance of the Mariner 9 television cameras (1973)
    In:  CASI
    Details
    Publication Date: 2006-03-27
    Description: Based on limited data, the Mariner 9 performance appears consistent throughout its mission. Several corrections have been provided by inflight verification sequences. A change in photometric response, which will impair precise photometric analysis, has been observed. Hence, only qualified photometric measurement appears feasible under limited conditions. Conversely, certain geometric and electronic parameters appear both measurable and congruent with preflight prediction. The role of inflight verification has been emphasized by these data to assess the in situ camera health and to promote efficient data analysis and interpretation.
    Keywords: COMMUNICATIONS
    Type: Mariner Mars 1971 Proj., Vol. 4; p 499-510
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 13
    facet.materialart.
    Unknown
    Millimeter wavelength observations of solar active regions (1973)
    In:  CASI
    Details
    Publication Date: 2006-04-05
    Description: Polarization properties of active regions at 9 mm are discussed, and the observed degree of polarization is used to obtain an estimate of chromospheric magnetic fields. Also discussed is the polarization structure at 9 mm of an active region that produced a minor flare around 1900 UT on September 28, 1971. Total power observations indicate that new regions develop, or weak regions intensify at millimeter wavelengths as a result of bursts at distant sites. The spectra of the peak flux density of moderately strong bursts observed at 9 mm show a sharp drop toward the shorter millimeter wavelengths. The weak bursts at 3.5 mm are manifest mainly as heating phenomena.
    Keywords: COMMUNICATIONS
    Type: NASA, Washington High Energy Phenomena on the Sun; p 104-113
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 14
    facet.materialart.
    Unknown
    Spectral characteristics of microwave bursts (1973)
    In:  CASI
    Details
    Publication Date: 2006-04-05
    Description: Various statistical parameters of the peak flux-density spectra of solar microwave bursts have been examined for 1968 to 1971 based on spectra obtained from fixed-frequency observations at 245, 606, 1415, 2695, 4995, 8800, 15400, and 35000 MHz. For bursts having a centimeter-radiation component, the great majority were found to have type C spectra (single spectral maximum) in the L-band to K-band range. A small percentage had miscellaneous type spectra (more than one spectral maximum) and another small percentage had what might be taken as thermal spectra. Even for gradual rise-and-fall bursts often thought to be thermal origin, less than 20 percent were found to have spectra which could be classified as thermal. The relationship between the burst spectral maximum (f sub max) and the photospheric magnetic field strength of the region associated with the burst was examined. A tendency for greater correlation at higher f sub max for stronger magnetic fields is noted; however, this is over-shadowed by the overall high correlations for those regions having strong photospheric magnetic fields.
    Keywords: COMMUNICATIONS
    Type: NASA, Washington High Energy Phenomena on the Sun; p 87-103
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 15
    facet.materialart.
    Unknown
    Optical communication system performance with tracking error induced signal fading. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: System performance is determined for an optical communication system using noncoherent detection in the presence of tracking error induced signal fading assuming (1) binary on-off modulation (OOK) with both fixed and adaptive threshold receivers, and (2) binary polarization modulation (BPM). BPM is shown to maintain its inherent 2- to 3-dB advantage over OOK when adaptive thresholding is used, and to have a substantially greater advantage when the OOK system is restricted to a fixed decision threshold.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 16
    facet.materialart.
    Unknown
    136-MHz/400-MHz radio-sky maps. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: A radio-sky map, covering the whole celestial sphere, is helpful for determining the system noise temperature of an earth-based satellite receiving system. Detailed sky maps for the 136- and 400-MHz space research (space-to-earth) satellite frequency bands have been generated, using a computer, by the National Aeronautics and Space Administration (NASA).
    Keywords: COMMUNICATIONS
    Type: IEEE; vol. 61
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 17
    facet.materialart.
    Unknown
    Preemphasis for an S-band constant bandwidth FM/FM system. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Preemphasis schedules are given for 11 constant-bandwidth FM subcarriers modulating an S-band transmitter at various receiver SNRs (9 dB, 15 dB and 25 dB). The criterion for establishing these preemphasis curves is the achievement, at various receiver IF SNR, of equal receiver output SNR for all channels. The empirically derived results are compared with a simplified, analytically derived schedule and the primary differences are explained. The S-band preemphasis schedule is also found to differ from the lower frequency VHF case.
    Keywords: COMMUNICATIONS
    Type: Telemetry Journal; 8; Dec
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 18
    facet.materialart.
    Unknown
    Telecommunication systems engineering (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Telecommunication network concepts are discussed together with carrier-tracking loops employing the phase-lock principle, phase and Doppler measurements in two-way phase-coherent tracking systems, range measurements by phase-coherent techniques, and questions of phase-coherent detection with perfect reference signals and with noisy reference signals. The design of one-way and two-way phase-coherent communication systems is considered, giving attention to the optimal design of single-channel systems, the design of two-channel systems, and the design of multichannel systems. Other topics explored include the design and the performance of phase-coherent systems preceded by band-pass limiters, symbol synchronization and its effects on data detection, noncoherent communication over the Gaussian channel, and tracking loops with improved performance.
    Keywords: COMMUNICATIONS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 19
    facet.materialart.
    Unknown
    Compression of weather charts by the segmented Lynch-Davisson code. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The Lynch-Davisson (L-D) code is shown to be efficient for compressing line-scanned weather charts wherein each line is divided into equal-length segments, and a separate L-D code is generated for each segment. As the number of segments increases, the L-D code length decreases appreciably, thereby simplifying the encoding and decoding operations. However, the accompanying decrease in the overall compression ratio is relatively small.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; June 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 20
    facet.materialart.
    Unknown
    Intelligibility improvement of analog communication systems using an amplitude control technique. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: An amplitude control technique has been employed for use with analog voice communication systems, which improves low-level phoneme reception and eliminates the received noise between words and syllables. Tests were conducted on a narrow-band frequency-modulation simplex voice communication channel employing the amplitude control technique. Presented for both the modified rhyme word tests and the phonetically balanced word tests are a series of graphical plots of the tests' score distribution, mean, and standard deviation as a function of received carrier-to-noise power density ratio. At low received carrier-to-noise power density ratios, a significant improvement in the intelligibility was obtained. A voice intelligibility improvement of more than 2 dB was obtained for the modified rhyme test words, and a voice intelligibility improvement in excess of 4 dB was obtained for the phonetically balanced word tests.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; May 1973
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 21
    facet.materialart.
    Unknown
    Tracking the Apollo Lunar Rover with interferometry techniques. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Apollo 16 and 17 Lunar Rover position history while transporting astronauts over the lunar surface has been determined to a resolution of better than 1 m and uncertainties of less than 25 m utilizing a specialized very-long baseline interferometry (VLBI) tracking technique. This paper describes the technique, discusses the National Aeronautics and Space Administration worldwide tracking system used to obtain data, discusses the data, and presents results.
    Keywords: COMMUNICATIONS
    Type: IEEE; vol. 61
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 22
    facet.materialart.
    Unknown
    Multipath modeling for aeronautical communications. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: One of the fundamental technical problems in aeronautical digital communications is that of multipath propagation between aircraft and ground terminal. This paper examines in detail a model of the received multipath signal that is useful for application of modern detection and estimation theories. The model treats arbitrary modulation and covers the selective and nonselective cases. The necessarily nonstationary statistics of the received signal are determined from the link geometry and the surface roughness parameters via a Kirchhoff solution.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; May 1973
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 23
    facet.materialart.
    Unknown
    The definition of cross polarization. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Consideration of three alternate definitions of cross-polarization known to the author. The three definitions are expressed precisely in terms of the same antenna pattern coordinate system, and the relative merits of the various definitions are discussed. One of the definitions is shown to be the proper choice for describing source current polarizations, another is suitable for relating source current distributions to secondary patterns, and the third is the best choice for describing antenna patterns.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Antennas and Propagation; AP-21; Jan. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 24
    facet.materialart.
    Unknown
    On the Feasibility of Efficient Multiamplitude Communication (1973)
    In:  CASI
    Details
    Publication Date: 2016-03-01
    Description: Bandwidth constraints in earth-satellite communication systems force consideration of uncoded M-ary modulation to obtain increased data rates. M-ary phase shift keying (MPSK) at first glance seems most promising because of the high transmitter efficiency achieved through Class C operation. Multiple phase-and-amplitude modulation candidates such as quadrature amplitude shift keying (QASK) appear less promising because the transmitter must operate at lower efficiency (in linear or multimode operation). However, initial studies indicate that QASK offers significant raw dc-power savings over MPSK, despite the reduced transmitter efficiency. For example, at S-band both solid-state and traveling wave tube (TWT) QASK transmitters can provide a 3-dB average dc-power savings over comparable 16-ary phase shift keying (PSK) for the same bit rate and error probability. The reason for this savings is that QASK requires much less average signal-to-noise ratio than 16-ary PSK for the same error rate.
    Keywords: COMMUNICATIONS
    Type: JPL Quart. Tech. Rev.; Vol. 2; No. 4; p 62-71
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 25
    facet.materialart.
    Unknown
    A note on signal enhancement for dual magnetometer systems. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Demonstration of the value of cross-correlation signal enhancement achieved by means of a dual magnetometer system. A unique feature of a dual magnetometer system is, as pointed out by Ness et al. (1971), the opportunity it allows for signal enhancement by using cross-correlation techniques developed in statistical communication theory. Their use is shown to make it possible to overcome the limitations that the intrinsic sensor ambient noise and the measurement-contaminating spacecraft field fluctuations impose upon the signal detection performance of a single magnetometer.
    Keywords: COMMUNICATIONS
    Type: Journal of Geophysical Research; 78; Apr. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 26
    facet.materialart.
    Unknown
    Observations of noise bands associated with the upper hybrid resonance by the Imp 6 radio astronomy experiment. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The intense noise bands occurring near the upper hybrid resonance frequency have been observed with the Imp 6 GSFC radio astronomy experiment in the plasmasphere. The identification of the upper hybrid resonance provides an accurate measure of the local electron density and allows the observed noise data to be fit to the scale of characteristic frequencies in the plasma. The data are consistent with earlier theoretical interpretations in which noise is generated between the upper hybrid and plasma frequencies and propagates to region 4 of the CMA diagram, where it is reflected at the L = 0 plasma cutoff.
    Keywords: COMMUNICATIONS
    Type: Journal of Geophysical Research; 78; Apr. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 27
    facet.materialart.
    Unknown
    Video-signal improvement using comb filtering techniques. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Significant improvement in the signal-to-noise performance of television signals has been obtained through the application of comb filtering techniques. This improvement is achieved by removing the inherent redundancy in the television signal through linear prediction and by utilizing the unique noise-rejection characteristics of the receiver comb filter. Theoretical and experimental results describe the signal-to-noise ratio and picture-quality improvement obtained through the use of baseband comb filters and the implementation of a comb network as the loop filter in a phase-lock-loop demodulator. Attention is given to the fact that noise becomes correlated when processed by the receiver comb filter.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; Apr. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 28
    facet.materialart.
    Unknown
    A theoretical and experimental study of non-ducted VLF waves after propagation through the magnetosphere. (1973)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: The nonducted propagation of artificial VLF waves through the magnetosphere has been studied by means of data obtained by the FR-1 satellite experiment, in which fixed frequency (16.8 kHz) waves radiated by a transmitter at the ground (at L equals 2.1) are received by the satellite, at 750 km altitude, both in the zone close to the transmitter and in the conjugate zone. From the wave-normal directions and Doppler shifts measured in the conjugate zone, it has been possible to identify waves that have been propagated from the Northern to the Southern Hemisphere in both ducted and nonducted modes. In this paper, the main features of the nonducted wave have been interpreted by ray tracing in models of the magnetosphere. The results improve our understanding as to why very few whistlers are observed on the ground at low latitudes.
    Keywords: COMMUNICATIONS
    Type: Journal of Atmospheric and Terrestrial Physics; 35; Jan. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 29
    facet.materialart.
    Unknown
    Attenuation and phase dispersion in the atmosphere due to the microwave spectrum of oxygen (1973)
    In:  CASI
    Details
    Publication Date: 2012-05-23
    Description: Radio wave propagation in the 40- to 140-GHz band through the earth's atmosphere is strongly influenced by the behavior of the O2 microwave spectrum. This behavior causes the transfer function to depend critically upon altitude. The spectroscopic properties of O2 are discussed and reduced to engineering formulas expressing attenuation and phase dispersion rates in terms of frequency and meteorological parameters. The theory is supported on several accounts by reliable spectroscopic measurements. Pressure scanning spectroscopy is used to investigate the O2 microwave spectrum under simulated atmospheric conditions. The application of spectroscopic information to analytical treatments of transfer properties for inhomogeneous slant paths is demonstrated. Attenuation and phase dispersion between 49 and 72 GHz are evaluated for zenith and tangential paths.
    Keywords: COMMUNICATIONS
    Type: AGARD Telecommun. Aspects on Freq. Between 10 and 100 GHz; 18 p
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 30
    facet.materialart.
    Unknown
    Voice intelligibility in satellite mobile communications (1973)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An amplitude control technique is reported that equalizes low level phonemes in a satellite narrow band FM voice communication system over channels having low carrier to noise ratios. This method presents at the transmitter equal amplitude phonemes so that the low level phonemes, when they are transmitted over the noisey channel, are above the noise and contribute to output intelligibility. The amplitude control technique provides also for squelching of noise when speech is not being transmitted.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Technol., 1972; p 195-198
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 31
    facet.materialart.
    Unknown
    ATS-5 millimeter wave propagation measurements (1973)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Long term experimental measurements to determine the propagation characteristics of 15 and 32 GHz earth-space links and to evaluate performance characteristics of operational millimeter wave systems are reported. The ATS 5 millimeter wave experimental link experienced attenuation and fading characteristics as a function of rainfall rate and other meteorological parameters. A method of site selection for the lowest attenuation rainfall rate improved reception tremendously.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Technol., 1972; p 171-174
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 32
    facet.materialart.
    Unknown
    Coordination procedure for radio relay and communication satellite services (1973)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A global rain rate statistic model is used to link microwave propagation statistics to measurable rain statistics in order to develop international telecommunication site criteria for radio relay and communication satellite services that minimize interference between receivers and transmitters. This rain coordination procedure utilizes a rain storm cell size, a statistical description of the rainfall rate within the cell valid for most of the earth's surface, approximations between Raleigh scatter and constancy of precipitation with altitude, and an analytic relation between radar reflectivity and rain rate.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Technol., 1972; p 175-178
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 33
    facet.materialart.
    Unknown
    High efficiency ground data transmission (1973)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: It is demonstrated that state-of-the-art communications technology can be implemented and reliably operated on a global basis to increase the transmission rates and efficiencies on circuits with bandwidths greater than the typical speech channel. Optimization is affected by optimum clock recovery procedures, multilevel pulse amplitude modulation, single sideband amplitude modulation, transversal filter equalizers, data scrambling, and active compensation for phase instability.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Technol., 1972; p 113-115
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 34
    facet.materialart.
    Unknown
    A zero-error operational video data compression system (1973)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A data compression system has been operating since February 1972, using ATS spin-scan cloud cover data. With the launch of ITOS 3 in October 1972, this data compression system has become the only source of near-realtime very high resolution radiometer image data at the data processing facility. The VHRR image data are compressed and transmitted over a 50 kilobit per second wideband ground link. The goal of the data compression experiment was to send data quantized to six bits at twice the rate possible when no compression is used, while maintaining zero error between the transmitted and reconstructed data. All objectives of the data compression experiment were met, and thus a capability of doubling the data throughput of the system has been achieved.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Technol., 1972; p 199-204
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 35
    facet.materialart.
    Unknown
    Health/education telecommunications experiment (1973)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The use of ATS 6 spacecraft in a general telecommunication link for the health/education experiment demonstrates the feasibility of the small receiver-only terminal consisting of a ten foot diameter antenna located on a three-legged mount. The terminal is capable of 0 to 70 degrees elevation, course adjustment, and a plus or minus 5 degree elevation vernier adjustment. Its tuned radio frequency receiver utilizes a cavity back dipole feed and a preamplifier. The indoor unit provides further RF gain and drives a wideband limiter-discriminator.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Technol., 1972; p 204-207
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 36
    facet.materialart.
    Unknown
    Adaptive ground implemented phase array (1973)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The simulation of an adaptive ground implemented phased array of five antenna elements is reported for a very high frequency system design that is tolerant to the radio frequency interference environment encountered by a tracking data relay satellite. Signals originating from satellites are received by the VHF ring array and both horizontal and vertical polarizations from each of the five elements are multiplexed and transmitted down to ground station. A panel on the transmitting end of the simulation chamber contains up to 10 S-band RFI sources along with the desired signal to simulate the dynamic relationship between user and TDRS. The 10 input channels are summed, and desired and interference signals are separated and corrected until the resultant sum signal-to-interference ratio is maximized. Testing performed with this simulation equipment demonstrates good correlation between predicted and actual results.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Technol., 1972; p 103-108
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 37
    facet.materialart.
    Unknown
    ERTS wideband tape recorder (1973)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The ERTS video bandwith tape recorder uses a rotary head to run the tape in transverse mode; the head wheel gives a head-to-tape surface speed of nearly 5080 centimeter per second. The electronics unit handles 15 megabit per second rate with a bit-error rate of 0.00001. An operational unit onboard ERTS A returned images from the 85 to 90 percent of the earth that are not available in real time.
    Keywords: COMMUNICATIONS
    Type: Significant Accomplishments in Technol., 1972; p 67-70
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 38
    facet.materialart.
    Unknown
    Nonlinear analysis of phased-locked loops with rapidly varying phase (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The performance of command and telemetry systems, useful in deep-space communications, is frequently affected by the radio-frequency phase error which is introduced at the point of reception by means of the carrier tracking loop. In low data rate communications, this phase error may vary rapidly over the duration of the signaling interval. In this paper such phase variation is characterized by a sinusoidal input phase, K sin (omega sub o t+, pi/6), which models a typical phase variation in communication over turbulent media. Conditions for synchronization stability and the acquisition behavior are examined by detailed computer study of the phase-plane trajectories for the second and third-order loops with perfect integrator. It is demonstrated that for the phase variation considered the third-order loop has no real advantage over the second-order loop. Finally, it is shown that nonzero initial conditions may result in large steady-state phase error.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-132889 , EE-209(73)
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 39
    facet.materialart.
    Unknown
    A one way Doppler tracking system for satellite to satellite tracking (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An S-band tracking system employing one way Doppler applicable to the tracking and data relay system (TDRS) was evaluated. This evaluation is limited to the measurement system parameters. The analysis assumes state-of-the-art components such as spacecraft oscillator long term stability of one part in 10 to the 8th power and ground station oscillator stability of one part in 10 to the 11th power. Signal characteristics comparable with the present ranging systems are utilized in the analysis. Predicated upon measurement system parameters, position uncertainties for the low orbiting spacecraft vary from 5 meters to 2 kilometers along track, 4 meters to 1 kilometer cross track, and 1 meter to 180 meters radially depending upon the tracking geometry and the high satellite position and velocity error assumptions.
    Keywords: COMMUNICATIONS
    Type: NASA-TM-X-70526 , X-591-73-307
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 40
    facet.materialart.
    Unknown
    Virginia precipitation scatter experiment: Data analysis (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Rain scatter and surface rain rate data were obtained from October 3, 1970 to October 2, 1971 using a bistatic radar system and tipping bucket rain gauges located in southeastern Virginia. The data showed that interference may occur between earth and terrestrial stations located within 80 km of each other either by mainlobe-to-mainlobe coupling or sidelobe-to-mainlobe coupling. The data further show that the distributions of scattering cross section per unit volume measured at several heights and estimated from surface rain gauge data were different. The density functions for the scattering cross section per unit volume values measured at a 3 km height and estimated from surface rain rate data were identical only for summer thundershowers. The data showed that the CCIR model used to estimate interference due to rain is inadequate because the cell size and change of scattering cross section per unit volume with height estimates of the model predict transmission loss values that are too low (more interference than will occur).
    Keywords: COMMUNICATIONS
    Type: NASA-TM-X-70457 , X-750-73-55-REV
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 41
    facet.materialart.
    Unknown
    Estimation and detection of signals in multiplicative noise (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A class of detection-estimation problems on matrix Lie groups is defined in which the observation noise is multiplicative in nature. By examining the differential versions of the hypotheses, which are bilinear in nature, it is possible to derive the relevant likelihood ratio formula and the associated optimal estimation equations for the signal given the observations and the assumption that the signal is present. These estimation equations are of interest in their own right, in that they represent a finite dimensional optimal solution to a nonlinear estimation problem and can be viewed as consisting of a Kalman-Bucy filter along with the on-line computation of the solution of the associated Riccati equation, which is driven by the observations. The usefulness of these results is illustrated via an example concerning the detection of an actuator failure in a rigid body rotational control system.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-136301 , ESL-P-521
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 42
    facet.materialart.
    Unknown
    An experimental study of the temporal statistics of radio signals scattered by rain (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A fixed-beam bistatic CW experiment designed to measure the temporal statistics of the volume reflectivity produced by hydrometeors at several selected altitudes, scattering angles, and at two frequencies (3.6 and 7.8 GHz) is described. Surface rain gauge data, local meteorological data, surveillance S-band radar, and great-circle path propagation measurements were also made to describe the general weather and propagation conditions and to distinguish precipitation scatter signals from those caused by ducting and other nonhydrometeor scatter mechanisms. The data analysis procedures were designed to provide an assessment of a one-year sample of data with a time resolution of one minute. The cumulative distributions of the bistatic signals for all of the rainy minutes during this period are presented for the several path geometries.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-136275 , OT-15
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 43
    facet.materialart.
    Unknown
    Measurements of VLF polarization and wave normal direction on OGO-F (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A major achievement of the F-24 experiment on OGO 6 was a verification of the theory of the polarization of proton whistlers. As predicted, the electron whistler was found to be right-hand polarized and the proton whistler left hand polarized. The transition from right- to left-hand polarization was found to occur very rapidly. Thus it appears that the experimental technique may allow great accuracy in the measurement of the cross-over frequency, a frequency that provides information on the ionic composition of the ionosphere.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-132882 , NSSDC-ID-69-051A-24-PM
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 44
    facet.materialart.
    Unknown
    Computer-aided communication satellite system analysis and optimization (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The capabilities and limitations of the various published computer programs for fixed/broadcast communication satellite system synthesis and optimization are discussed. A satellite Telecommunication analysis and Modeling Program (STAMP) for costing and sensitivity analysis work in application of communication satellites to educational development is given. The modifications made to STAMP include: extension of the six beam capability to eight; addition of generation of multiple beams from a single reflector system with an array of feeds; an improved system costing to reflect the time value of money, growth in earth terminal population with time, and to account for various measures of system reliability; inclusion of a model for scintillation at microwave frequencies in the communication link loss model; and, an updated technological environment.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-136201 , R(T)-73/2
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 45
    facet.materialart.
    Unknown
    Telemetry coding study for the international magnetosphere explorers mother-daughter and heliocentric missions. Volume 1: Summary (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The convolutional coding study on the IME Mother-Daughter and Heliocentric spacecraft is reported. The three major tasks involved in the study are summarized.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-132880 , ASAO-PR20046-4-VOL-1
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 46
    facet.materialart.
    Unknown
    Reflection and interference of electromagnetic waves in inhomogeneous media (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Solutions were obtained of the wave equation for a plane horizontally polarized electro-magnetic wave incident on a semi infinite two dimensional inhomogeneous medium. Two problems were considered: An inhomogeneous half space, and an inhomogeneous layer of arbitrary thickness. Solutions of the wave equation were obtained in terms of Hankel functions with complex arguments. Numerical calculations were made of the reflection coefficient R at the interface of the homogeneous medium. The startling results show that the reflection coefficient for a complex dielectric constant with gradient, can be less than that of the same medium with zero gradient.
    Keywords: COMMUNICATIONS
    Type: NASA-TM-X-70518 , X-650-73-297
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 47
    facet.materialart.
    Unknown
    Electro-optical processing of phased array data (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An on-line spatial light modulator for application as the input transducer for a real-time optical data processing system is described. The use of such a device in the analysis and processing of radar data in real time is reported. An interface from the optical processor to a control digital computer was designed, constructed, and tested. The input transducer, optical system, and computer interface have been operated in real time with real time radar data with the input data returns recorded on the input crystal, processed by the optical system, and the output plane pattern digitized, thresholded, and outputted to a display and storage in the computer memory. The correlation of theoretical and experimental results is discussed.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-124375
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 48
    facet.materialart.
    Unknown
    Digital data detection and synchronization (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The primary accomplishments have been in the analysis and simulation of receivers and bit synchronizers. It has been discovered that tracking rate effects play, a rather fundamental role in both receiver and synchronizer performance, but that data relating to recorder time-base-error, for the proper characterization of this phenomenon, is in rather short supply. It is possible to obtain operationally useful tape recorder time-base-error data from high signal-to-noise ratio tapes using synchronizers with relatively wideband tracking loops. Low signal-to-noise ratio tapes examined in the same way would not be synchronizable. Additional areas of interest covered are receiver false lock, cycle slipping, and other unusual phenomena, which have been described to some extent in this and earlier reports and simulated during the study.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-132809
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 49
    facet.materialart.
    Unknown
    Preflight SL-1/SL-3 Skylab VHF ranging coverage (nominal TPI). Antenna and propagation studies for spacecraft systems, task E-531 (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A preflight assessment of the Skylab VHF ranging coverage for the rendezvous portion of the nominal SL-1/SL-3 mission is reported, assuming a 27 July 1973 SL-3 launch. Data are based on a nominal attitude trajectory, which has the Saturn workshop in a solar inertial attitude throughout the rendezvous; the CSM terminal phase initiation maneuver is nominal. An addendum to this report is being prepared, which considers the effects of early and late TPI maneuvers. Curves are presented which show the variation in received power levels on both spacecraft-to-spacecraft links from about 600 n.mi. range to CSM and SWS station keeping. Appropriate threshold levels are shown on these received power curves to indicate zero circuit margins for the ranging function.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-133981 , TRW-20029-H203-R0-00
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 50
    facet.materialart.
    Unknown
    Transmitter and receiver antenna gain analysis for laser radar and communication systems (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A comprehensive and fairly self-contained study of centrally obscured optical transmitting and receiving antennas is presented and is intended for use by the laser radar and communication systems designer. The material is presented in a format which allows the rapid and accurate evaluation of antenna gain. The Fresnel approximation to scalar wave theory is reviewed and the antenna analysis proceeds in terms of the power gain. Conventional range equations may then be used to calculate the power budget. The transmitter calculations, resulting in near and far field antenna gain patterns, assumes the antenna is illuminated by a laser operating in the fundamental cavity mode. A simple equation is derived for matching the incident source distribution to a general antenna configuration for maximum on-axis gain. An interpretation of the resultant gain curves allows a number of auxiliary design curves to be drawn which display the losses in antenna gain due to pointing errors and the cone angle of the outgoing beam as a function of antenna size and central obscuration. The use of telescope defocusing as an approach to spreading the beam for target acquisition is compared to some alternate methods.
    Keywords: COMMUNICATIONS
    Type: NASA-TM-X-70423 , X-524-73-185
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 51
    facet.materialart.
    Unknown
    Composite antenna feed (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A composite antenna feed subsystem concentrated in a small area at the prime focus of the parabola of a satellite parabolic reflector accomodates a plurality of frequency bands. The arrays comprising the subsystem are mounted on the top cover of a communication module. A multimode horn is arranged at the center of the subsystem axis which functions at X- And C-band frequencies, and a cross array consisting of individual elements form the S-band feed, with one arm of the S-band array containing an element mutually shared with the L-band array. Provision is also made for UHF frequencies, and a dipole arrangement for VHF frequencies is arranged around the S-band arms.
    Keywords: COMMUNICATIONS
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 52
    facet.materialart.
    Unknown
    Apollo 17 mission anomaly report no. 1: Erroneous measurements transmitted by telemetry (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Results are presented of analyses conducted to determine why erroneous data were transmitted by 60 of the 1 sample-per-second telemetry channels of Apollo 17 for a 2-minute period beginning at about 191 hours 40 minutes. Reasons for the failure and corrective actions taken are described.
    Keywords: COMMUNICATIONS
    Type: NASA-TM-X-69367 , JSC-07985
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 53
    facet.materialart.
    Unknown
    Vanguard/PLACE experiment system design and test plan (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The design, development, and testing of the NASA-GFSC Position Location and Aircraft Communications Equipment (PLACE) at C band frequency are discussed. The equipment was installed on the USNS Vanguard. The tests involved a sea test to evalute the position-location, 2-way voice, and 2-way data communications capability of PLACE and a trilateration test to position-fix the ATS-5 satellite using the PLACE system.
    Keywords: COMMUNICATIONS
    Type: NASA-TM-X-66287 , X-752-73-117
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 54
    facet.materialart.
    Unknown
    The radiation from apertures in curved surfaces (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The geometrical theory of diffraction is extended to treat the radiation from apertures or slots in convex, perfectly-conducting surfaces. It is assumed that the tangential electric field in the aperture is known so that an equivalent, infinitesimal source can be defined at each point in the aperture. Surface rays emanate from this source which is a caustic of the ray system. A launching coefficient is introduced to describe the excitation of the surface ray modes. If the field radiated from the surface is desired, the ordinary diffraction coefficients are used to determine the field of the rays shed tangentially from the surface rays. The field of the surface ray modes is not the field on the surface; hence if the mutual coupling between slots is of interest, a second coefficient related to the launching coefficient must be employed. In the region adjacent to the shadow boundary, the component of the field directly radiated from the source is presented by Fock-type functions. In the illuminated region the incident radiation from the source (this does not include the diffracted field components) is treated by geometrical optics. This extension of the geometrical theory of diffraction is applied to calculate the radiation from slots on elliptic cylinders, spheres and spheroids.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-2263
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 55
    facet.materialart.
    Unknown
    Error analysis for Mariner Venus/Mercury 1973 conducted at the JPL Mesa west antenna range (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Theoretical analysis and experimental data are combined to yield the errors to be used with antenna gain, antenna patterns, and RF cable insertion loss measurements for the Mariner Venus-Mercury 1973 Flight Project. These errors apply to measurements conducted at the JPL Mesa, West Antenna Range, on the high gain antenna, low gain antenna, and RF coaxial cables.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-133230 , JPL-TM-33-625
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 56
    facet.materialart.
    Unknown
    Collapsible high gain antenna (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A lightweight small high gain antenna which is capable of being packaged in a collapsed form and automatically expanded when in use is described. The antenna includes a cylindrical housing having a rod with a piston adjacent to one end extending through it. Attached to the outer end of the rod in a normally collapsed state is a helical wire coil. When the gas producing means is activated the piston and rod are shifted outwardly to expand the wire coil. A latch is provided for holding the helical coil in the expanded position.
    Keywords: COMMUNICATIONS
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 57
    facet.materialart.
    Unknown
    The NASA role in major areas of human concern: Communication (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: After introducing some of the general factors that have affected progress in the area of communication, NASA program elements are examined to illustrate relevant points of contact. Interpretive steps are taken throughout the report to show a few of the more important ways people's lives have been affected as a result of the work of NASA and other organizations functioning in this area. The principal documents used and interviews conducted are identified.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-133052
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 58
    facet.materialart.
    Unknown
    Motion of metric type 4 radio sources and its relation to shock waves responsible for type 2 radio bursts (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The relation of the motion of type 4mA sources with shock waves responsible for type 2 bursts were considered using the observed data for these two radio sources. The difference of the emission mechanism between type 2 and type 4mA bursts suggest that the moving speed of the shock waves mentioned above is not necessarily equal to the metric type 4 sources. By analyzing the observed data on the speeds for both type 2 and type 4 sources., it was found that type 4 bursts decelerate and often cease to move in the solar envelop and that type 2 sources move at higher speeds than type 4 sources.
    Keywords: COMMUNICATIONS
    Type: NASA-TM-X-70557 , X-690-73-367
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 59
    facet.materialart.
    Unknown
    Optimum detection of an optical image on a photoelectric surface. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The image-detecting performance of an optimum counting detector is compared with that of a threshold detector and that of a detector basing its decisions on the total number of photoelectrons from a finite area of the image. The illuminance of the image is assumed to have a Gaussian spatial distribution. The optimum detector works with the pristine datum (and not with the photoelectric response) which is the spatiotemporal electromagnetic field at the aperture of the observing optical instrument. It is shown that little is to be gained by using details of the illuminance distribution beyond the crude knowledge of its breadth as embodied in a simple counter of emitted photoelectrons. All three detectors exhibit accordingly about the same reliability.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-9; July 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 60
    facet.materialart.
    Unknown
    On the noniterative solution of integral equations for scattering of electromagnetic waves. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: COMMUNICATIONS
    Type: Journal of Mathematical Physics; 14; Aug. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 61
    facet.materialart.
    Unknown
    Recursive ideal observer detection of known M-ary signals in multiplicative and additive Gaussian noise. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: This paper presents the derivation of the recursive algorithms necessary for real-time digital detection of M-ary known signals that are subject to independent multiplicative and additive Gaussian noises. The motivating application is minimum probability of error detection of digital data-link messages aboard civil aircraft in the earth reflection multipath environment. For each known signal, the detector contains one Kalman filter and one probability computer. The filters estimate the multipath disturbance. The estimates and the received signal drive the probability computers. Outputs of all the computers are compared in amplitude to give the signal decision. The practicality and usefulness of the detector are extensively discussed.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; Aug. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 62
    facet.materialart.
    Unknown
    The effects of channel errors in DPCM systems and comparison with PCM systems. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Sampling, quantization, and channel errors in differential pulse-code modulation (DPCM) systems are considered and compared to results obtained with standard pulse-code modulation (PCM) systems. DPCM and PCM are compared for three different reconstruction filters. The optimum prediction coefficient is shown to depend on the channel noise.-
    Keywords: COMMUNICATIONS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 63
    facet.materialart.
    Unknown
    Interference patterns of a horizontal electric dipole over layered dielectric media. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Interference patterns for electromagnetic fields due to a subsurface reflector below a layered lossy dielectric are calculated with the geometrical optics approximation for use in interpreting data to be collected on the moon by Apollo 17 as well as data currently being obtained on terrestrial glaciers. The radiating antenna lies on the surface. All six field components are calculated and studied. For the endfire solutions, the peak of the first reflected wave is found to be different from that of the broadside ones. To facilitate a physical discussion, we plotted the radiation patterns due to the antenna on the surface.
    Keywords: COMMUNICATIONS
    Type: Journal of Geophysical Research; 78; June 10
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 64
    facet.materialart.
    Unknown
    Antenna admittance determination of electron density. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A circular-aperture flush-mounted antenna for which a theoretical description of the antenna-plasma interaction has been developed was used to obtain a comparison between theoretical and experimental antenna admittance in the presence of ionized boundary layers of low-collision frequency. The antenna was located in a flat-plate model which was in turn located in the expanding-flow environment of a reflected-shock tunnel. The electron-temperature and electron-density distributions in the plate boundary layer at the antenna location were independently measured using voltage-swept thin-wire Langmuir probes for one of the test conditions. The antenna admittance was measured using a four-probe microwave reflectometer and these measured values were found to be in good agreement with those predicted from the theory. Measurements were also performed with another type of circular-aperture antenna which did not satisfy all of the constraints of the theoretical model, although good agreement was obtained between the calculations and the experimental results.
    Keywords: COMMUNICATIONS
    Type: AIAA Journal; 11; July 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 65
    facet.materialart.
    Unknown
    Numerical comparisons of a modified Rayleigh approach with other rough surface EM scattering solutions. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A modification of the classical Rayleigh technique utilizing the fast Fourier transform, developed into the so-called Rayleigh-FFT method for electromagnetic scattering, is shown to obtain valid scattering results from arbitrary irregular periodic structures composed of a rough layer over a rough half-space. The considerable usefulness of the Rayleigh approach is thus established, and Beckmann's (1968) contention (that the convergence of the method is reasonably rapid only if the roughness is very slight) is refuted.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Antennas and Propagation; AP-21; May 1973
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 66
    facet.materialart.
    Unknown
    Beam-pointing errors of planar-phased arrays. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Using both analytical and Monte Carlo techniques, beam-pointing errors of planar-phased arrays are analyzed. The obtained simple formulas for rms pointing errors are applicable to uniform planar arrays with both uniform and Gaussian uncorrelated phase-error distributions and for any arbitrary scan angle.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Antennas and Propagation; AP-21; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 67
    facet.materialart.
    Unknown
    Determination of the maximum scan-gain contours of a beam-scanning paraboloid and their relation to the Petzval surface. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Antennas and Propagation; AP-21; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 68
    facet.materialart.
    Unknown
    An empirical model for average F-layer scintillation at VHF/UHF. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: An empirical approach to modeling the electron-density irregularities in the F layer that are primarily responsible for amplitude scintillation of VHF/UHF signals has been devised and tested. An irregularity model was postulated as a function of geomagnetic latitude, local time of day, season, and sunspot number. The primary parameters of the irregularities that were postulated were their strength and transverse scale-size. The irregularities were assumed to be aligned along the geomagnetic field, and their axial ratio was taken as constant, as were the height and thickness of the irregular layer. The model is offered as a tool for VHF/UHF communication-systems planning, to the extent that the average value of scintillation in a specified circumstance is of engineering value.
    Keywords: COMMUNICATIONS
    Type: Radio Science; 8; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 69
    facet.materialart.
    Unknown
    Bistatic-radar estimation of surface-slope probability distributions with applications to the moon. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A method for extracting surface-slope frequency distributions from bistatic-radar data has been developed and applied to the lunar surface. Telemetry transmissions from orbiting Apollo spacecraft were received on the earth after reflection from the lunar surface. The echo-frequency spectrum was related analytically to the probability distribution of lunar slopes. Standard regression techniques were used to solve the inverse problem of finding slope distributions from observed echo-frequency spectra. Data taken simultaneously at two wavelengths, 13 and 116 cm, have yielded diverse slope statistics.
    Keywords: COMMUNICATIONS
    Type: Radio Science; 8; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 70
    facet.materialart.
    Unknown
    Statistics for ionospherically diffracted VHF/UHF signals. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: In this paper, a general characterization of the statistics for an ionospherically diffracted, monochromatic plane wave is presented. The main results are restricted to weak scatter, although two possible extensions that accommodate large phase perturbations and multiple scatter are discussed. A detailed discussion of the first-order statistics of amplitude is given. The general Gaussian distribution is discussed together with its Nakagami-distribution approximation and the log-normal distribution. By using a segment of ATS-3 satellite data recorded at Lima, Peru, we show equally good fits to Gaussian and log-normal distributions at least for the limited dynamic range available. The Nakagami distribution provides only a poor approximation.
    Keywords: COMMUNICATIONS
    Type: Radio Science; 8; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 71
    facet.materialart.
    Unknown
    An analytical expression for the limits of error in the measurement of reflection-coefficient phase. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Microwave Theory and Techniques; MTT-21; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 72
    facet.materialart.
    Unknown
    Information in the time of arrival of a photon packet - Capacity of PPM channels. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Keywords: COMMUNICATIONS
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 73
    facet.materialart.
    Unknown
    Digital single-sideband modulation. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: This paper considers digitized Weaver modulators for single-sideband modulation that can be used in radio communications and telemetering. A system of 12 such modulators to process 12 analog signals digitally is replaced by six multiplex modulators at the cost of additional computation at the input but with an overall reduction in computation time and a higher degree of accuracy. A unique digital filter is developed that can interpolate and output samples at multiples of the input sampling rate and exhibits a passband that occurs above the Nyquist frequency with no apparent distortion effects. A discussion of the Fortran simulation of a combined modulator-demodulator structure is included to verify the effectiveness of this scheme.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 74
    facet.materialart.
    Unknown
    Note on the error signal of block quantizers. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Demonstration that the error signal incurred by block quantizing stationary data is nonstationary under some conditions. Examples are presented which indicate that the mean square error is largest at the block edges. When block quantizers are used to encode pictures at low bit rates, this effect tends to make the block edges visible in the reconstructed picture.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; Mar. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 75
    facet.materialart.
    Unknown
    Propagation through a slab of irregularities in a magneto-ionic medium. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: A theory is developed to describe the propagation of characteristic waves through an infinite slab of irregularities in a magneto-ionic medium. The theory makes use of the asymptotic Green's dyadic. The results show that mode conversion is possible through scattering from irregularities in an anisotropic background. Some special cases are discussed and an example is given.
    Keywords: COMMUNICATIONS
    Type: Franklin Institute; vol. 295
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 76
    facet.materialart.
    Unknown
    Comparison of Te and Ti from Ogo 6 and from various incoherent scatter radars. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Langmuir probe and retarding potential analyzer (RPA) data on the electron and ion temperatures Te and Ti obtained from Ogo 6 are compared with Te and Ti values obtained from the incoherent scatter network. The satellite to radar temperature ratio TeS/TeR is 1.15 on the average for these comparisons. This discrepancy is larger than the uncertainties usually placed on the probe and radar Te values. The ion temperature ratio TiS/TiR approximately 1.0, independent of the particular radar examined. This comparison serves as an intercalibration of the incoherent scatter network.
    Keywords: COMMUNICATIONS
    Type: NSSDC-ID-69-051A-02-PM , NSSDC-ID-69-051A-03-PM , Journal of Geophysical Research; 78; Jan. 1
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 77
    facet.materialart.
    Unknown
    Automatic carrier acquisition system (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An automatic carrier acquisition system for a phase locked loop (PLL) receiver is disclosed. It includes a local oscillator, which sweeps the receiver to tune across the carrier frequency uncertainty range until the carrier crosses the receiver IF reference. Such crossing is detected by an automatic acquisition detector. It receives the IF signal from the receiver as well as the IF reference. It includes a pair of multipliers which multiply the IF signal with the IF reference in phase and in quadrature. The outputs of the multipliers are filtered through bandpass filters and power detected. The output of the power detector has a signal dc component which is optimized with respect to the noise dc level by the selection of the time constants of the filters as a function of the sweep rate of the local oscillator.
    Keywords: COMMUNICATIONS
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 78
    facet.materialart.
    Unknown
    Planning alternative organizational frameworks for a large scale educational telecommunications system served by fixed/broadcast satellites (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: This memorandum explores a host of considerations meriting attention from those who are concerned with designing organizational structures for development and control of a large scale educational telecommunications system using satellites. Part of a broader investigation at Washington University into the potential uses of fixed/broadcast satellites in U.S. education, this study lays ground work for a later effort to spell out a small number of hypothetical organizational blueprints for such a system and for assessment of potential short and long term impacts. The memorandum consists of two main parts. Part A deals with subjects of system-wide concern, while Part B deals with matters related to specific system components.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-133646 , MEMO-73/3
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 79
    facet.materialart.
    Unknown
    Two carrier communication system with single transmitter (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A pulse code modulated communication system is disclosed for transmitting two subcarrier modulated carriers from a single transmitter comprising two channels for phase modulating the two carriers independently. The modulating subcarriers are independently modulated by data and/or pseudonoise (PN) codes as desired. The modulated carriers are switched alternately to the single transmitter in synchronism with operation of a PN code generator when PN code modulation is present, as for ranging.
    Keywords: COMMUNICATIONS
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 80
    facet.materialart.
    Unknown
    Investigate optimum way of adding wideband capability and recommend a design for modification of one government furnished AM baseband demultiplexer (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The hardware design and implementation and test results are described of the accommodation of two wideband channels, 8 kHz DSB/QDSB located at 44 kHz and 16 kHz SSB, lower sideband, located at 104 kHz in a government furnished FDM demultiplexer unit.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-124267 , MCR-73-92
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 81
    facet.materialart.
    Unknown
    Intruder detection system (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An intruder detection system is described. The system contains a transmitter which sends a frequency modulated and amplitude modulated signal to a remote receiver in response to a geophone detector which responds to seismic impulses created by the intruder. The signal makes it possible for an operator to determine the number of intruders and the manner of movement.
    Keywords: COMMUNICATIONS
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 82
    facet.materialart.
    Unknown
    Technology requirements for post-1985 communications satellites (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The technical and functional requirements for commercial communication satellites are discussed. The need for providing quality service at an acceptable cost is emphasized. Specialized services are postulated in a needs model which forecasts future demands. This needs model is based upon 322 separately identified needs for long distance communication. It is shown that the 1985 demand for satellite communication service for a domestic region such as the United States, and surrounding sea and air lanes, may require on the order of 100,000 MHz of bandwith. This level of demand can be met by means of the presently allocated bandwidths and developing some key technologies. Suggested improvements include: (1) improving antennas so that high speed switching will be possible; (2) development of solid state transponders for 12 GHz and possibly higher frequencies; (3) development of switched or steered beam antennas with 10 db or higher gain for aircraft; and (4) continued development of improved video channel compression techniques and hardware.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-114679
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 83
    facet.materialart.
    Unknown
    Theoretical and experimental studies of reentry plasmas (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A viscous shock-layer analysis was developed and used to calculate nonequilibrium-flow species distributions in the plasma layer of the RAM vehicle. The theoretical electron-density results obtained are in good agreement with those measured in flight. A circular-aperture flush-mounted antenna was used to obtain a comparison between theoretical and experimental antenna admittance in the presence of ionized boundary layers of low collision frequency. The electron-temperature and electron-density distributions in the boundary layer were independently measured. The antenna admittance was measured using a four-probe microwave reflectometer and these measured values were found to be in good agreement with those predicted. Measurements were also performed with another type of circular-aperture antenna and good agreement was obtained between the calculations and the experimental results. A theoretical analysis has been completed which permits calculation of the nonequilibrium, viscous shock-layer flow field for a sphere-cone body. Results are presented for two different bodies at several different altitudes illustrating the influences of bluntness and chemical nonequilibrium on several gas dynamic parameters of interest. Plane-wave transmission coefficients were calculated for an approximate space-shuttle body using a typical trajectory.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-2232 , CAL-AF-3093-A-2
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 84
    facet.materialart.
    Unknown
    An all digital low data rate communication system (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The advent of digital hardwares has made it feasible to implement many communication system components digitally. With the exception of frequency down conversion, the proposed low data rate communication system uses digital hardwares completely. Although the system is designed primarily for deep space communications with large frequency uncertainty and low signal-to-noise ratio, it is also suitable for other low data rate applications with time-shared operation among a number of channels. Emphasis is placed on the fast Fourier transform receiver and the automatic frequency control via digital filtering. The speed available from the digital system allows sophisticated signal processing to reduce frequency uncertainty and to increase the signal-to-noise ratio. The practical limitations of the system such as the finite register length are examined. It is concluded that the proposed all-digital system is not only technically feasible but also has potential cost reduction over the existing receiving systems.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-130234 , EE-73-2
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 85
    facet.materialart.
    Unknown
    The electromagnetic radiation from simple sources in the presence of a homogeneous dielectric sphere (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: In this research, the effect of a homogeneous dielectric sphere on the electromagnetic radiation from simple sources is treated as a boundary value problem, and the solution is obtained by the technique of dyadic Green's functions. Exact representations of the electric fields in the various regions due to a source located inside, outside, or on the surface of a dielectric sphere are formulated. Particular attention is given to the effect of sphere size, source location, dielectric constant, and dielectric loss on the radiation patterns and directivity of small spheres (less than 5 wavelengths in diameter) using the Huygens' source excitation. The computed results are found to closely agree with those measured for waveguide-excited plexiglas spheres. Radiation patterns for an extended Huygens' source and for curved electric dipoles located on the sphere's surface are also presented. The resonance phenomenon associated with the dielectric sphere is studied in terms of the modal representation of the radiated fields. It is found that when the sphere is excited at certain frequencies, much of the energy is radiated into the sidelobes. The addition of a moderate amount of dielectric loss, however, quickly attenuates this resonance effect. A computer program which may be used to calculate the directivity and radiation pattern of a Huygens' source located inside or on the surface of a lossy dielectric sphere is listed.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-2211
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 86
    facet.materialart.
    Unknown
    Eight channel telephone telemetry system (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A portable, indirectly coupled telephone system is reported which transmits/to a central receiving site eight channels of EEG data of sufficient fidelity for screening and/or limited diagnostic use. The system requires no electrical connection to the telephone at the transmitter or at the receiver and is compatible with common EEG recording practice for real-time recording. It accepts 8 input channels simultaneously with one telephone transmitter and one telephone receiver operates from standard power sources.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-128877
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 87
    facet.materialart.
    Unknown
    An integral-equation solution for TE radiation and scattering from conducting cylinders (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The piecewise-sinusoidal reaction technique is applied to low frequency radiation and scattering from noncircular cylinders with perfect or imperfect conductivity. This report presents the theory, computer programs and numerical results for these two-dimensional problems with the TE polarization.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-2245 , TR-2902-7
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 88
    facet.materialart.
    Unknown
    Spacecraft communications terminal breadboard components (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The C-band translator, transmitter, and attenuator are described for the spacecraft communication terminal breadboard components. The block diagram is also included for the C-band receiver. The system performance data and the mechanical properties of the system are briefly considered.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-128859
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 89
    facet.materialart.
    Unknown
    Frequency division multiplex technique (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A system for monitoring a plurality of condition responsive devices is described. It consists of a master control station and a remote station. The master control station is capable of transmitting command signals which includes a parity signal to a remote station which transmits the signals back to the command station so that such can be compared with the original signals in order to determine if there are any transmission errors. The system utilizes frequency sources which are 1.21 multiples of each other so that no linear combination of any harmonics will interfere with another frequency.
    Keywords: COMMUNICATIONS
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 90
    facet.materialart.
    Unknown
    Doppler compensation by shifting transmitted object frequency within limits (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A system and method are disclosed for position locating, deriving centralized air traffic control data, and communicating via voice and digital signals between a multiplicity of remote aircraft, including supersonic transports, and a central station. Such communication takes place through a synchronous satellite relay station. Side tone ranging patterns, as well as the digital and voice signals, are modulated on a carrier transmitted from the central station and received on all of the supersonic transports. Each aircraft communicates with the ground stations via a different frequency multiplexed spectrum. Supersonic transport position is derived from a computer at the central station and supplied to a local air traffic controller. Position is determined in response to variable phase information imposed on the side tones at the aircrafts. Common to all of the side tone techniques is Doppler compensation for the supersonic transport velocity.
    Keywords: COMMUNICATIONS
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 91
    facet.materialart.
    Unknown
    NASCOM network: Ground communications reliability report (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A reliability performance analysis of the NASCOM Network circuits is reported. Network performance narrative summary is presented to include significant changes in circuit configurations, current figures, and trends in each trouble category with notable circuit totals specified. Lost time and interruption tables listing circuits which were affected by outages showing their totals category are submitted. A special analysis of circuits with low reliabilities is developed with tables depicting the performance and graphs for individual reliabilities.
    Keywords: COMMUNICATIONS
    Type: NASA-TM-X-66220 , X-843-73-41
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 92
    facet.materialart.
    Unknown
    Determining distance to lightning strokes from a single station (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Apparatus is described for determining the distance to lightning strokes from a single station. The apparatus includes a first loop antenna system for sensing the magnetic field produced by the lightning which is filtered, square rooted, and fed into a peak voltage holding circuit. A second antenna is provided for sensing the electric field produced by the lightning which is fed into a filter, an absolute value meter, and to a peak voltage holding circuit. A multivibrator gates the magnetic and electric signals through the peak holding circuits to a ratio meter which produces a signal corresponding to the ratio between the magnetic component and the electric component. The amplitude of this signal is proportional to the distance from the apparatus to the lightning stroke.
    Keywords: COMMUNICATIONS
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 93
    facet.materialart.
    Unknown
    Location of Lunakhod 2 from laser ranging observations (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Results of laser ranging attempts on Lunakhod 2 are presented. Laser ranging can only be accomplished at night, so only the straight-line distance between the end points of a daytime traverse can be determined. Uncertainties of positional determination are strongly dependent on the length of the tracking arc. The data, obtained in the first two lunar nights, are too sparse to yield reliable positional determinations. The results clearly illustrate the critical importance of a high-quality lunar ephemeris for the interpretation of sparse data.
    Keywords: COMMUNICATIONS
    Type: COSPAR Information Bulletin no. 68; Dec. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 94
    facet.materialart.
    Unknown
    A square-root data array solution of the continuous-discrete filtering problem (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The Dyer-McReynolds (1969) discrete square-root filtering algorithm is extended to accommodate continuous dynamics. Differential equations are given to represent the time evolution of the filter data array. These equations are nonlinear, but it is shown that the nonlinearities act to enhance the stability of the solution.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Automatic Control; AC-18; Dec. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 95
    facet.materialart.
    Unknown
    Synthetic aperture radar system design for random field classification (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: An optimum design study is carried out for synthetic aperture radar systems intended for classifying randomly reflecting areas (such as agricultural fields) characterized by a reflectivity density spectral density. The problem solution is obtained, neglecting interfield interference and assuming areas of known configuration and location, as well as a certain Gaussian signal field property. The optimum processor is nonlinear, but includes conventional matched filter processing. A set of summary design curves is plotted, and is applied to the design of a satellite synthetic aperture radar system.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-9; Sept
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 96
    facet.materialart.
    Unknown
    Hexagonal multiple phase-and-amplitude-shift-keyed signal sets (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Selection of a particular signal set array for a bandwidth-constrained multiple phase-and-amplitude-shift-keyed (MPASK) communication system for a linear additive Gaussian noise channel requires consideration of factors such as average and/or peak power vs symbol error probability, signal amplitude dynamic range, simplicity of generation and detection, and number of bit errors per symbol error (Gray code properties). A simple technique is presented for generating and optimally detecting the honeycomb (hexagonal) signal set, i.e., the signal set that has the tightest sphere-packing properties. The symbol and bit error probability performance of this set is compared to other two-dimensional signal sets that have been investigated in the literature, and is shown to be slightly superior from an average power standpoint. The paper concludes with a comparison of all of these signal sets from the standpoint of the factors listed above.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Communications; COM-21; Oct. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 97
    facet.materialart.
    Unknown
    ATS-F Comsat Millimeter Wave Propagation Experiment (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: The ATS-F Comsat Millimeter Wave Propagation Experiment has been designed to gather statistical data on the attenuation caused by rain at millimeter wave frequencies. These data will be used to determine system design parameters for future communications satellite systems operating at frequencies above 10 GHz. The experiment has 39 ground terminals transmitting at 13.2 or 17.8 GHz to a transponder on board the ATS-F satellite. The transponder retransmits these signals at 4 GHz to a central earth terminal which records their amplitudes once each second. The data will be analyzed to provide probabilities of attenuation as functions of parameters such as rainfall, location, and time. These probabilities can then be used to determine the required power margins of millimeter wave communications systems. Techniques of overcoming severe attenuation such as site diversity and the use of a spot beam to increase the power level at selected locations will also be evaluated.
    Keywords: COMMUNICATIONS
    Type: COMSAT Technical Review; 3; Fall 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 98
    facet.materialart.
    Unknown
    Bounds on the performance of a class of digital communication systems (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Bounds on the capacity of a class of digital communication channels are derived. Equating the bounds on capacity to rate-distortion functions of (typical) sources in turn produces bounds on the performance of a class of digital communication systems. For ratios of squared quantization level to noise variance much less than one, the power requirements for this class of digital communication systems are shown to be within approximately 3 dB of the theoretical optimum.
    Keywords: COMMUNICATIONS
    Type: IEEE Transactions on Information Theory; IT-19; Nov. 197
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 99
    facet.materialart.
    Unknown
    Telemetry link for an automatic salmon migration monitor (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The antenna and transmitter described in this report were designed for integration into the remote acoustic assessment system for detection of sockeye salmon in the Bristol Bay region of the Bering Sea. The assessment system configuration consists of an upward directed sonar buoy anchored 150 ft below the surface and attached by cable to a spar buoy tethered some 300 ft laterally. The spar buoy contains a telemetry transmitter, power supply, data processing electronics, an antenna and a beacon light.
    Keywords: COMMUNICATIONS
    Type: NASA-CR-138152
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
  • 100
    facet.materialart.
    Unknown
    The position and size of radio sources associated with solar electron events (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The positions and sizes of the sources of type 3 bursts which are associated with interplanetary electron events ( 45 keV) are observed by the 80-MHz Culgoora radioheliograph. The sizes of the responsible electron streams at 0.6 solar radius in the corona are much smaller than the cones of propagation of the electrons in interplanetary space. Many of the type 3 bursts are shown to be accompanied by a type 5 continuum, and it is argued that the observation of a type 3 to 5 radio burst implies an increased spreading of electrons at heights 0.6 solar radius, consistent with the extent of the propagation cone of the electrons in interplanetary space.
    Keywords: COMMUNICATIONS
    Type: NASA, Washington High Energy Phenomena on the Sun; p 594-601
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...