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  • COMMUNICATIONS AND RADAR
  • INSTRUMENTATION AND PHOTOGRAPHY
  • 1980-1984  (510)
  • 1975-1979  (871)
  • 1950-1954
  • 1983  (510)
  • 1977  (456)
  • 1976  (415)
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  • 1980-1984  (510)
  • 1975-1979  (871)
  • 1950-1954
Year
  • 1
    Publication Date: 2004-12-04
    Description: An improved 4 to 18 micron array camera system was developed at NASA Goddard SFC for astronomical photometry, using an Aerojet Electro Systems Corp. 16 x 16 Si:Bi accumulation mode charge injection device (AMCID) which could be suitable for eventual low-background spaceflight applications. An astronomical observing program using this device was carried out as a collaboration between NASA Goddard (Infrared and Radio Astronomy Branch and Micro Electronics Branch), the Harvard/Smithsonian Center for Astrophysics, and Steward Observatory of the University of Arizona. In 1983 the camera system was revised, and a new Aeroject Si:Bi array with 16 x 16 active pixels was obtained from NASA/Ames Research Center as part of a new scientific collaboration between the Ames and Goddard infrared array research groups. The 16 x 16 device had sufficiently good sensitivity, uniformity and noise characteristics to be used for successful observations at the Mt. Lemmon 60 and 61 inch telescopes in May 1983. Complete laboratory characterization of the 16 x 16 array was carried out in summer of 1983. Initial results indicate that this detector has sensitivity and noise characteristics comparable to other devices from the same generation of Aerojet arrays.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Ames Research Center, Infrared Detector Technology Workshop; 12 p
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  • 2
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    Publication Date: 2006-01-16
    Description: The selection of measurement systems for experiments conducted in the context of a space flight must be guided by the criteria applicable to any scientific study requiring objective measurements of physiological variables. Steps fundamental to the process of choosing the best instrumentation system are identified and the key factors in matching the operational characteristics of the instrumentation to its intended use are discussed. Special problems in obtaining data from nonhuman primates, whether restrained or unrestrained, are explored. Choices for data processing are evaluated as well as the use of prototype flight tests and simulations to assess future life science experiments for spacelab or payloads for the space shuttle biomedical scientific satellite.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Use of Nonhuman Primates in Space; p 225-243
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  • 3
    Publication Date: 2011-08-18
    Description: Link margin estimates are calculated for 30/20 GHz satellite communication systems employing closely-spaced (4 to 100 km) 'dual diversity' switched ground sites. The link margin estimates are based on a new analysis in which the bivariate rain attenuation density function for two correlated ground sites is modelled by an exponential density function. The results of the exponential density function analysis enable derivation of a direct relation between rain margin estimates and probability of exceedance (link availability). Margins typically in the range 2 to 12 dB are calculated for various ground site separations and summarized for seven city locations and five satellite orbit positions over the U.S. The results can be easily extended to other EHF satellite frequencies and other locations.
    Keywords: COMMUNICATIONS AND RADAR
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  • 4
    Publication Date: 2011-08-18
    Description: It is shown that, for convolutionally coded transmission over bandwidth-constrained channels, a mere reversal of the switching direction at the encoder output produces a change in the system bit error probability performance. This change is significant when the Viterbi demodulator/decoder is matched to the total channel memory and is more significant for linear channels than for nonlinear ones. The reversal of switching direction is a simple demonstration of the fact that the well-known optimum codes for the linear AGWN channel are no longer necessarily optimum for a bandwidth-constrained channel with or without the addition of channel nonlinearity. It is concluded that potentially significant performance improvement can be obtained by matching the encoder (through the appropriate choice of tap weights and modulo-2 summers) to the channel in addition to matching the demodulator/decoder to the channel for a given encoder.
    Keywords: COMMUNICATIONS AND RADAR
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  • 5
    Publication Date: 2011-08-18
    Description: New frequency calibration tables are required to keep abreast of the resolution attainable by currently available tunable lasers. One key to the generation of tables with requisite accuracy involves accurate heterodyne frequency measurements; another key consists of reliable fitting and analysis. Coordinated activity in NBS involves selection of suitable molecular calibration candidates, their frequency measurement and analysis, and dissemination of the results in the form of frequency calibration tables. Current status of these efforts is described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 6
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    Publication Date: 2011-08-18
    Description: A new extension to optogalvanic spectroscopy, in which electrons detached from negative ions formed in the discharge are observed as a function of incident laser wavelength, has been developed. The determination of the electron affinities of I(-) and Cl(-) atomic ions is described. The potential of the technique for studying the spectroscopy of molecular negative ions is also discussed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal de Physique (ISSN 0449-1947); 44; C7-461 t
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  • 7
    Publication Date: 2011-08-18
    Description: A holographic interferometer system has been installed in the NASA Ames 2- by 2-Foot Transonic Wind Tunnel. The system incorporates a modern 10 pps, Nd:YAG pulsed laser which provides reliable operation and is easy to align. The spatial filtering requirements of the unstable resonator beam are described, as well as the integration of the system into the existing schlieren system. A two-plate holographic interferometer is used to reconstruct flow field data. For static wind tunnel models, the single exposure holograms are recorded in the usual manner; however, for dynamic models such as oscillating airfoils, synchronous laser hologram recording is used.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 8
    Publication Date: 2011-08-18
    Description: A new two-wavelength lidar technique for remotely measuring the pressure profile using the trough absorption region between two strong lines in the oxygen A band is described. The theory of integrated vertical path, differential ranging, and horizontal-path pressure measurements is given, with methods to desensitize and correct for temperature effects. The properties of absorption troughs are described and shown to reduce errors due to laser frequency jitter by up to two orders of magnitude. A general analysis, including laser bandwidth effects, demonstrates that pressure measurements with an integrated-vertical-path technique are typically fifty times more accurate than with a differential ranging technique. Simulations show 0.1-0.3 percent accuracy for ground and Shuttle-based pressure-profile and surface-pressure experiments.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; 3759-377
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  • 9
    Publication Date: 2011-08-18
    Description: Airborne laser-induced, depth-resolved water Raman backscatter is useful in the detection and mapping of water optical transmission variations. This test, together with other field experiments, has identified the need for additional field experiments to resolve the degree of the contribution to the depth-resolved, Raman-backscattered signal waveform that is due to (1) sea surface height or elevation probability density; (2) off-nadir laser beam angle relative to the mean sea surface; and (3) the Gelbstoff fluorescence background, and the analytical techniques required to remove it. When converted to along-track profiles, the waveforms obtained reveal cells of a decreased Raman backscatter superimposed on an overall trend of monotonically decreasing water column optical transmission.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics (ISSN 0003-6935); 22; 3778-378
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  • 10
    Publication Date: 2011-08-18
    Description: The error probability performance of differential detection of narrow-band FM is determined and compared with the analogous results for limiter-discriminator detection of the same modulation. It is shown that over a large class of benign and hostile environments, e.g., Gaussian IF filter, AWGN, partial-band noise jamming, the differential detector offers no theoretical performance advantage over the limiter-discriminator receiver with integrate-and-dump postdetection filtering.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications (ISSN 0090-6778); COM-31; 1227-123
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  • 11
    Publication Date: 2011-08-17
    Description: The absolute counting efficiency and pulse height distributions of a continuous-channel electron multiplier used in the detection of hydrogen, argon and xenon ions are assessed. The assessment technique, which involves the post-acceleration of 8-eV ion beams to energies from 100 to 4000 eV, provides information on counting efficiency versus post-acceleration voltage characteristics over a wide range of ion mass. The charge pulse height distributions for H2 (+), A (+) and Xe (+) were measured by operating the experimental apparatus in a marginally gain-saturated mode. It was found that gain saturation occurs at lower channel multiplier operating voltages for light ions such as H2 (+) than for the heavier ions A (+) and Xe (+), suggesting that the technique may be used to discriminate between these two classes of ions in electrostatic analyzers.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 48; Aug. 197
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  • 12
    Publication Date: 2011-08-17
    Description: The physical conditions in laboratory gases and in the upper atmosphere of the planets, including earth, can be deduced from a measurement of the intensity and line profile of different radiating molecules. Because of the low pressures in the upper atmospheres, many molecular lines with small pressure-broadening coefficients are collisionally narrowed. These lines are resolvable with a Fabry-Perot interferometer. Analytical expressions are given relating the measured line intensity and profile to the true line intensity and profile. A deconvolution of the measured profile gives the parameters A, beta, and K characterizing the collisionally narrowed Galatry profile. General expressions for the nonideal interferometer are discussed, and, specifically, mirror defects and a limited detector aperture are treated.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 16; June 197
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  • 13
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    Publication Date: 2011-08-17
    Description: Using a modified version of the classical Cornu spiral, fading patterns in agreement with observations of radio signals on 140 and 360 MHz from the geostationary satellite ATS6, have been obtained. The particular fading patterns chosen show modulated quasi-periodic fading before and after a deep central minimum. It is shown that a cylindrical lens in the ionosphere required to produce this is only about 100 m across (an order of magnitude smaller than the size of the pattern on the ground) and if it were circular in cross-section would have a maximum plasma frequency of over 40 MHz. This suggests the reason why calculations based on a transparent phase screen did not give the observed fading pattern for 40 MHz signals. It was not possible to deduce the height of the lens above the ground, though we would incline to an E-region origin.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Journal of Atmospheric and Terrestrial Physics; 39; Mar. 197
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  • 14
    Publication Date: 2011-08-17
    Description: A general development is undertaken to determine the limitations on the use of beam-limited target-referenced radars in the measurement of ocean wave height. This class of radars is concerned only with the range extent of the target, not the range to the target. The nonzero range extent of a flat waveless sea and the compounding effect of pointing errors due to radar platform instability cause difficulty in measuring low wave heights and impose a maximum operating altitude on such systems. It is seen that it is impractical to obtain accurate measurements for wave heights of interest at altitudes above those used by commercial aircraft (10,000 m). Additionally, the typical ratio of dominant wavelength to significant wave height (SWH) of 30 for wind-driven gravity waves imposes an upper limit on the SWH measurable for a given altitude and beamwidth.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-25; May 1977
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  • 15
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    Publication Date: 2011-08-17
    Description: There exists a need for a relatively inexpensive system for measuring strain in bolts. The torque wrench is one technique for straining bolts which has been widely applied. Unfortunately, friction in the bolt threads and between the nut and the work tend to make such a simple system inaccurate. In practice, a torque wrench is unacceptable for many situations where strain is critical. In this article, an ultrasonic technique is described which can indicate changes in bolt strain to better than one part in 10,000. The technique is based on the one-dimensional propagating-ultrasonic-wave model and uses a new ultrasonic instrument called a Reflection Oscillator Ultrasonic Spectrometer which is a closed-loop feedback marginal-oscillator system that frequency locks the device to the peak of a mechanical resonance in the bolt. The instrument indicates a shift in the bolt resonance frequency due to elongation and changes in velocity of sound due to strain. Data are presented comparing a standard torque wrench to the ultrasonic monitor for different measured stresses on the bolt as well as for different bolt conditions. The strain instrument can be used to monitor changing stresses, to measure material properties and may be applied as a strain gage or load cell.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Experimental Mechanics; 17; May 1977
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  • 16
    Publication Date: 2011-08-17
    Description: The implementation and tracking performance of symbol synchronizers for Manchester coded data is presented with motivation provided by maximum a posteriori (MAP) estimation theory. Certain physically relizable closed-loop structures, readily implemented in practice, are suggested by the theory for uncoded data symbols with arbitrary data transition probabilities. The tracking performance of these loops is optimized and comparisons are made among the various configurations over a wide range of system parameters. Although not the major intent of the paper, the acquisition problem is briefly addressed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-25; Apr. 197
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  • 17
    Publication Date: 2011-08-17
    Description: A portable boundary-layer meteorological data-acquisition and analysis system is described which employs a small tethered balloon and a programmable calculator. The system is capable of measuring pressure, wet- and dry-bulb temperature, wind speed, and temperature fluctuations as a function of height and time. Other quantities, which can be calculated in terms of these, can also be made available in real time. All quantities, measured and calculated, can be printed, plotted, and stored on magnetic tape in the field during the data-acquisition phase of an experiment.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Boundary-Layer Meteorology; 10; Aug. 197
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  • 18
    Publication Date: 2011-08-17
    Description: Aperture illumination is synthesized through the use of overlapping subarrays with independently controlled excitations. Detailed analysis and design criteria are provided for a specific limited-scan antenna configuration scanning in one plane. The number of phase shifts is the theoretical minimum corresponding to specified aperture size and field of view. Beam pointing and width are approximately constant for moderate frequency variation, and ultralow sidelobes outside the field of view can be produced at the cost of a slight loss of illumination efficiency. Accurate aperture illumination control makes for excellent independently specified sum and difference patterns in beamforming.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-25; Mar. 197
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  • 19
    Publication Date: 2011-08-17
    Description: A color photograph of the peculiar elliptical galaxy NGC 5128 (Centaurus A) has been reconstructed from three Kodak 103a emulsion type photographs by projecting positives of the three B&W plates through appropriate filters onto a conventional color film. The resulting photograph shows color balance and latitude characteristics superior to color photographs of similar astronomical objects made with commercially available conventional color film. Similar results have been obtained for color reconstructed photographs of the Large and Small Magellanic Clouds. These and other results suggest that these projection-reconstruction techniques can be used to obtain high-quality color photographs of astronomical objects which overcome many of the problems associated with the use of conventional color film for the long exposures required in astronomy.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Applied Photographic Engineering; 2; Spring 1
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  • 20
    Publication Date: 2011-08-17
    Description: The performance of suppressed carrier receivers with Costas loop tracking is optimized by proper choice of loop arm filter bandwidth. In particular, it is shown that for a variety of passive arm filter types, there exists, for a given data rate and data signal-to-noise ratio, an optimum filter bandwidth in the sense of minimizing the loop's squaring loss. For the linear theory case, this is equivalent to minimizing the loop's tracking jitter. When symbol synchronization is known, it is shown that by replacing the passive arm filters with active filters, i.e., integrate-and-dump circuits, one can achieve an improvement in carrier-to-noise ratio of as much as 4 to 6 dB depending on the passive arm filter type used for comparison and the value of data signal-to-noise ratio.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-25; Feb. 197
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  • 21
    Publication Date: 2011-08-16
    Description: The versatility is demonstrated of the 41 cm. Tortugas reflector's photoelectric system through observations of V566 Oph and R CrB with four associated AAVSO comparison stars. These observations were made between May and October, 1974.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Contrib. of the Observatory of N. Mex. State Univ., Vol. 1, No. 4; p 154-158
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  • 22
    Publication Date: 2011-08-18
    Description: A general approach to the optimal control of large space antennas based on their RF/structural characteristics is described. The approach consists of defining a cost functional based on the degradation of the RF performance of the antenna and using the structural model as the dynamic system. The method is applied to the design of an optimal controller for a 55-m, wrap-rib offset-fed antenna. The controller's goal is to minimize the variations of the peak electric field of the antenna due to feed displacements.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Proc. of the Workshop on Appl. of Distributed System Theory to the Control of Large Space Struct.; p 181-194
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  • 23
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    Publication Date: 2011-08-18
    Description: A functional description of the GCF and its relationships with other elements of the DSN and NASCOM is presented together with development objectives and goals and comments on implementation activites in support of flight projects.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 200-209
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  • 24
    Publication Date: 2011-08-18
    Description: The operational mobile VLBI data acquisition system (MV-3) requires that a voice link be established between the mobile data system and a fixed site. A communications subsystem was incorporated in the MV-3 design which consists of HF radio, VHF mobile radio telephone and conventional land line telephone. The HF antenna design was optimized for short and long range transmission using both inverted V and yagi antennas mounted on a self-supporting telescoping mast.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 210-219
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  • 25
    Publication Date: 2011-08-18
    Description: Measurements of the S-band performance of the DSS 13 26-meter antenna, equipped with the second generation S-X common aperture feed, are reported. Aperture efficiency and overall antenna gain results are compared with predicted values. The elevation dependence of the aperture efficiency is reported.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 89-94
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  • 26
    Publication Date: 2011-08-18
    Description: Antenna arraying is a crucial Deep Space Network technique in maximizing the science return of planetary and comet encounters. The equations which describe the total figure of merit for a multiple system of arrayed antennas are developed. An example is given for three Canberra DSN antennas and the Parkes 64-m antenna to be arrayed for the Voyager 2 Uranus flyby.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 83-88
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  • 27
    Publication Date: 2011-08-18
    Description: A need for an accurate but inexpensive method for measuring and evaluating time delays of large ground antennas for VLBI applications motivated the development of the collimation tower technique. Supporting analytical work which was performed primarily to verify time delay measurement results obtained for a large antenna when the transmitter was at a collimation distance of 1/25 of the usual far field criterion is discussed. Comparisons of theoretical and experimental results are also given.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 20-29
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  • 28
    Publication Date: 2011-08-18
    Description: A class of receivers called conditionally nulling receivers is defined for quantum noise limited optical communications. These receivers have the ability to decide at each moment in time whether or not to coherently combine a predetermined local oscillator field with the received optical field, prior to performing an energy measurement (photodetection) on the combined field. Conditionally nulling receivers are applicable to pulse position modulation and related modulation schemes, which have the property that, at each moment in time, the transmitted signal is in one of only two states, on or off. The local oscillator field which may or may not be added by the receiver is an exact replica of the negative of the received on field; hence, the receiver can exactly null the on signal if the on signal is present and the receiver chooses to use the local field. An ideal conditionally nulling receiver achieves very nearly the same error probability (within a multiplicative factor varying froom 1 to 2.15) as the optimum quantum measurement for quantum noise limited detection of M-ary PPM signals. In contrast, other known receiving methods, such as direct, heterodyne, and homodyne detection, are exponentially suboptimum.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 30-42
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  • 29
    Publication Date: 2011-08-18
    Description: Eight dual channel microwave radiometers were constructed as a research and development effort for the Crustal Dynamics Project and the Deep Space Network. These instruments, known as water vapor radiometers, are primarily intended to demonstrate that the variable path delay imposed by atmospheric water vapor can be calibrated in microwave tracking and distance measuring systems but could also be used in other applications involving moist air meteorology and propagation studies. They are being deployed to various stations and observatories that participate in Very Long Baseline Interferometry experiments. The development history of these instruments are reviewed, the theory of operation and overall design considerations are outlined, and the instrumental parameters and performance characteristics are described.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Telecommun. and Data Acquisition Rept.; p 1-19
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  • 30
    Publication Date: 2011-08-17
    Description: Viking lander cameras have returned stereo and multispectral views of the Martian surface with a resolution that approaches 2 mm/lp in the near field. A two-orders-of-magnitude increase in resolution could be obtained for collected surface samples by augmenting these cameras with auxiliary optics that would neither impose special camera design requirements nor limit the cameras field of view of the terrain. Quasi-microscope images would provide valuable data on the physical and chemical characteristics of planetary regoliths.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 16; Sept
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  • 31
    Publication Date: 2011-08-17
    Description: This paper investigates several key questions concerning the mechanization and design of a Costas receiver for reconstruction of a carrier from a suppressed carrier signal. For baseband NRZ encoded data symbols and a soft bandpass limiter preceding the loop, several design issues which are considered herein and which affect acquisition and tracking performance are: (1) The choice of an IF bandwidth. (2) The optimum choice of the Costas arm filter bandwidths as well as the spectral roll-off characteristics. (3) The optimum choice of loop bandwidth to data rate ratio for a given signal-to-noise ratio. (4) The signal suppression factor and the combined limiter-squaring loss. (5) The variations in loop bandwidth and damping with signal level. (6) The choice of the limiter transfer characteristic. (7) Performance degradation due to the presence of a limiter. Various new results in system design are presented and typical numerical results are given and graphically demonstrated in SNR regions of practical interest. The theory is applicable to the design of carrier reconstruction loops required in the implementation of spread spectrum communication receivers.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-25; Aug. 197
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  • 32
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    Publication Date: 2011-08-17
    Description: It is noted that the stringent economy of data-collection systems consisting of several widely dispersed satellite-monitored sensor platforms can be partially achieved by using an inexpensive linearly polarized antenna on each platform and that due to Faraday rotation of the ionosphere, the satellite antenna must be circularly polarized to avoid a prohibitive polarization loss. The cumulative probability distribution of polarization loss between a linearly polarized platform antenna and an elliptically polarized satellite antenna is computed for satellite-antenna axial ratios of 3 and 4 dB. The results indicate that a polarization loss of 4.5 dB must be expected for a reliability of 85% and an axial ratio of 3 dB. It is suggested that the conventional assignment of a 3-dB polarization loss to the communication link considered may not insure the required link reliability.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-13; July 197
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  • 33
    Publication Date: 2011-08-17
    Description: An array of large multicrystal NaI(Tl) detectors was constructed and used in a balloon-borne experiment to observe weak transient bursts of cosmic origin. The array had an active area of about 1 sq m and was sensitive to photons above 50 keV. Localized bursts which were observed are attributed to long-lived phosphorescence following large energy deposits by cosmic rays in the crystals.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Nuclear Instruments and Methods; 140; 1976
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  • 34
    Publication Date: 2011-08-17
    Description: The maximum theoretical accuracy in the angular location of a radiating object that can be obtained by using a planar or linear array is studied. The elements are assumed to have identical radiation patterns and the complex voltages observed at their ports are assumed to be subject to phase measurement errors, having normal probability density. An optimum scheme for the statistical extraction of the parameters defining the direction is established noting that the presence of thermal noise does not affect the structure of the estimator. Comparisons with the conventional multiple interferometric techniques are made.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Aerospace and Electronic Systems; AES-13; Mar. 197
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  • 35
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    Publication Date: 2011-08-17
    Description: Three type VPM 164 photomultiplier tubes with III-IV compound InGaAsP reflective photocathodes were developed for use in ground-based and space-borne astronomical detectors. Although the achieved response of about 0.02% quantum efficiency at 1.083 microns fell short of the goal of 1% quantum efficiency, the broadband characteristics are still considerably better than those of the S-1 photocathode.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 16; Apr. 197
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  • 36
    Publication Date: 2011-08-17
    Description: The purposes of the joint Canadian-U.S. Communications Technology Satellite (CTS) Program are (1) to conduct satellite communication systems experiments using the 12- and 14-GHz bands and low-cost transportable ground terminals, (2) to develop and flight test a power amplifier tube having a greater than 50% efficiency with a saturated power output of 200 W at 12 GHz, (3) to develop and flight test a lightweight extendible solar array with an initial power output greater than 1 kW, and (4) to develop and flight test a 3-axis stabilization system to maintain accurate antenna boresight positioning on a spacecraft with flexible appendages. Brief descriptions of these experiments and of the ground facilities are provided.
    Keywords: COMMUNICATIONS AND RADAR
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  • 37
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    Publication Date: 2011-08-17
    Description: Laboratory and airborne experiments have proven the feasibility and demonstrated the techniques of an airborne pulsed laser system for rapidly mapping coastal water bathymetry. Water depths of 10 plus or minus 0.25 m were recorded in waters having an effective attenuation coefficient of 0.175 m. A 2-MW peak power Nd:YAG pulsed laser was flown at an altitude of 600 m. An advanced system, incorporating a mirror scanner, a high pulsed rate laser, and a good signal processor, could survey coastal zones at the rate of several square miles per hour.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 16; Jan. 197
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  • 38
    Publication Date: 2011-08-17
    Description: As the radio frequency spectrum becomes increasingly overcrowded, interference with mission-critical DSN operations is rising at an alarming rate. To alleviate this problem the DSN is developing a wideband surveillance system for on-site detection and identification of potential sources of radio frequency interference (RFI), which will complement the existing frequency coordination activities. The RFI monitoring system is based on a wideband, multi-look discrete spectrum analyzer operating on fast Fourier transform principles. An extensive general statistical analysis is presented of such spectrum analyzers and derives threshold detection performance formulas for signals of interest. These results are then applied to the design of the RFI spectrum analyzer under development.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 83-98
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  • 39
    Publication Date: 2011-08-17
    Description: Two CCD techniques were discussed for performing an N-point sampled data correlation between an input signal and an electronically programmable reference function. The design and experimental performance of an implementation of the direct time correlator utilizing two analog CCDs and MOS multipliers on a single IC were evaluated. The performance of a CCD implementation of the chirp z transform was described, and the design of a new CCD integrated circuit for performing correlation by multiplication in the frequency domain was presented. This chip provides a discrete Fourier transform (DFT) or inverse DFT, multipliers, and complete support circuitry for the CCD CZT. The two correlation techniques are compared.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; 6 p
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  • 40
    Publication Date: 2011-08-17
    Description: The maturity of self-scanned, solid-state, multielement photosensors makes the realization of "real time" reconnaissance photography viable and practical. A system built around these sensors which can be constructed to satisfy the requirements of the tactical reconnaissance scenario is described. The concept chosen is the push broom strip camera system -- RECON 6 -- which represents the least complex and most economical approach for an electronic camera capable of providing a high level of performance over a 140 deg wide, continuous swath at altitudes from 200 to 3,000 feet and at minimum loss in resolution at higher altitudes.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 129-134
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  • 41
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    Publication Date: 2011-08-17
    Description: The detection of signals using Walsh power spectral estimates is analyzed. In addition, a generalization of this method of estimation is evaluated. The conclusion is that Walsh transforms are not suitable tools for the detection of weak signals in noise.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 127-131
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  • 42
    Publication Date: 2011-08-17
    Description: A commercially available 1728 element shallow bulk channel CCD line array was clocked at output data rates up to 30 MHz. Temporal noise was near 200 electrons and was largely independent of clock rate. Charge transfer efficiency was in excess of 0.9999 at 30 MHz. Utilization is feasible for visual simulation and aerial mapping.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 72-82
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  • 43
    Publication Date: 2011-08-17
    Description: A pessimistic statistical model was developed for predicting the extent of radio frequency interference (RF1). Based on the assumptions underlying the model, DSN S-band operations can expect one RF1 interruption every 4.1 days, with the average incident lasting 24 s. This implies that 52 or more such satellites, with uncorrelated orbital trajectories, will cause in excess of 5 min of RF1 per day at a DSN station.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 69-77
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  • 44
    Publication Date: 2011-08-17
    Description: High performance CCD imagers with 800 x 50 resolution elements were fabricated using a coplanar, double polysilicon, electrode system. The imager was developed as a prototype to demonstrate the feasibility of an 800 x 800 array for application to deep space photography where data rates of 10K to the 2nd power and operating temperatures of -40 C are required. The performance is discussed and comparisons made to the existing 400 x 400 imager.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; 3 p
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  • 45
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    Publication Date: 2011-08-17
    Description: The design features and characteristics of interline transfer (ILT) CCD arrays with 190 x 244 and 380 x 488 image elements are reviewed, with emphasis on optional operating modes and system application considerations. It was shown that the observed horizontal resolution for a TV system using an ILT image sensor can approach the aperture response limit determined by photosensor site width, resulting in enhanced resolution for moving images. Preferred camera configurations and read out clocking modes for maximum resolution and low light sensitivity are discussed, including a very low light level intensifier CCD concept. Several camera designs utilizing ILT-CCD arrays are described. These cameras demonstrate feasibility in applications where small size, low-power/low-voltage operation, high sensitivity and extreme ruggedness are either desired or mandatory system requirements.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 152-156
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  • 46
    Publication Date: 2011-08-17
    Description: The Space Shuttle television system incorporates a versatile complement of TV equipment which allows the positioning, quantity, and performance capabilities of the multiple TV cameras to vary as dictated by the particular mission. However, current TV camera technology employing glass enclosed, vacuum processed image sensors results in a bulky device that restricts its location and versatility. Problems and potential solutions that can be achieved through the employment of solid-state image sensors for both monochrome and color applications are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 126-128
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  • 47
    Publication Date: 2011-08-17
    Description: A breadboard of the command detector signal-to-noise-ratio estimator and lock status monitor was built on a wire-wrap card. The breadboard was integrated with the standard command detector, and its performance was measured. The design, design constraints, and construction of the breadboard are described. The performance is shown to agree with the theoretical model.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 42-51
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  • 48
    Publication Date: 2011-08-16
    Description: An improved technique has been developed for studies of the shear viscosity of fluids. It utilizes an acoustic resonator as a four-terminal electrical device; the resonator's amplitude response may be determined directly and simply related to the fluid's viscosity. The use of this technique is discussed briefly and data obtained in several fluids is presented.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Acoustical Society of America; vol. 60
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  • 49
    Publication Date: 2011-08-17
    Description: An analysis of the use of ultraviolet narrow-band interference filters for total ozone determination is given with reference to the New Zealand filter spectrophotometer under the headings of filter monochromaticity, temperature dependence, orientation dependence, aging, and specification tolerances and nonuniformity. Quantitative details of each problem are given, together with the means used to overcome them in the New Zealand instrument. The tuning of the instrument's filter center wavelengths to a common set of values by tilting the filters is also described, along with a simple calibration method used to adjust and set these center wavelengths.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Applied Meteorology; 16; Aug. 197
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  • 50
    Publication Date: 2011-08-17
    Description: A liquid helium-cooled p-channel enhancement mode MOSFET, the 3N167, is found to have sufficiently low noise for use as a preamplifier with helium-cooled bolometers that are used in infrared astronomy. Its characteristics at 300, 77, and 4.2 K are presented. It is also shown to have useful application with certain photoconductive and photovoltaic infrared detectors.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 48; Apr. 197
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  • 51
    Publication Date: 2011-08-17
    Description: An apparatus and data analysis technique for measuring the gravitational force on freely falling electrons are described. The measurement required that all forces acting on the electrons be uniform and measurable to about ten to the negative 11th power eV/m. The electrical force along the axis of the 5-cm-diam, vertical copper tube used in the experiment was found to be about six times ten to the negative 11th power eV/m when the tube was cooled to 4.2 K. Forces on electrons due to magnetic field gradients were reduced well below the electrical ones by selecting only ground state electrons for measurement. The absence, at 4.2 K, of much stronger electric fields, which were expected to arise from the patch effect and from differential lattice components, contrasts strongly with measurements of electric fields near metal surfaces made at room temperature.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 48; Jan. 197
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  • 52
    Publication Date: 2011-08-17
    Description: The effect of the width and shape of the New Zealand filter instrument's passbands on measured total-ozone accuracy is determined using a numerical model of the spectral measurement process. The model enables the calculation of corrections for the 'bandwidth-effect' error and shows that highly attenuating passband skirts and well-suppressed leakage bands are at least as important as narrow half-bandwidths. Over typical ranges of airmass and total ozone, the range in the bandwidth-effect correction is about 2% in total ozone for the filter instrument, compared with about 1% for the Dobson instrument.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Applied Meteorology; 16; Aug. 197
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  • 53
    Publication Date: 2011-08-17
    Description: The spectral radiance of deuterium lamps calibrated by the Max-Planck-Institut fuer Astronomie (MPI), by the U.S. National Bureau of Standards (NBS), and by the Physikalisch-Technische Bundesanstalt (PTB) are compared to check the agreement of UV radiometric scales. The NBS group used the optically thin continuum radiation from a wall-stabilized hydrogen arc as its fundamental radiometric standard, while the MPI and PTB groups used the synchrotron radiation facility in DESY. It is found that the spectral radiance scales based upon the DESY synchrotron and the NBS hydrogen arc are consistent, at least for one wavelength relative to another.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 16; July 197
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  • 54
    Publication Date: 2011-08-17
    Description: A physical optics solution is presented for the scattering of plane waves from a perfectly conducting corrugated surface in the case of waves incident from an arbitrary direction and for an observer far from the surface. This solution is used to compute the radar cross section of the surface in the case of backscatter from irregular (i.e., stochastic) corrugations. An interesting feature of the solution is the occurrence of singularities in the scattered fields. These singularities appear to be a manifestation of focusing by the surface at its 'stationary' points. Whether or not the singularities occur in the solution depends on the manner in which one restricts the analysis to the far-field.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-24; Nov. 197
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  • 55
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    Publication Date: 2011-08-17
    Description: Images on developed photographic emulsions can be significantly intensified by making the image silver radioactive and exposing a second emulsion to this radiation. Because the print, an autoradiograph, reproduces the original with significant increases in density and contrast, the method can be used to enhance underexposed emulsions and to increase the limits of photographic detection. This paper reports a new, practical chemical method for activating the silver, using thiourea labeled with sulfur-35, a process convenient for use in photographic laboratories. Speed increases of 13 and contrast increases of 18 were achieved with Kodak Plus-X film in this initial phase.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 15; Nov. 197
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  • 56
    Publication Date: 2011-08-17
    Description: The previously derived DSN Radio Frequency Angular Tropospheric Refraction Model contained an assumption which was subsequently seen to be at a variance with the theoretical basis of angular refraction. The modification necessary to correct the model is minor in that the value of a constant is changed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 184-186
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  • 57
    Publication Date: 2011-08-17
    Description: An RFI channel to be a multiple-access channel is defined in which no sender can know when any other starts, and the problem of determining the relative phases of the senders at the receiver is studied. A new result is proved about binary DEBruijn sequences.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 103-108
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  • 58
    Publication Date: 2011-08-17
    Description: Observations of Viking differenced S-band/X-band (S-X) range are shown to correlate strongly with Viking Doppler noise. A ratio of proportionality between downlink S-band plasma-induced range error and two-way Doppler noise is calculated. A new parameter (similar to the parameter epsilon which defines the ratio of local electron density fluctuations to mean electron density) is defined as a function of observed data sample interval (Tau) where the time-scale of the observations is 15 Tau. This parameter is interpreted to yield the ratio of net observed phase (or electron density) fluctuations to integrated electron density (in RMS meters/meter). Using this parameter and the thin phase-changing screen approximation, a value for the scale size L is calculated. To be consistent with Doppler noise observations, it is seen necessary for L to be proportional to closest approach distance a, and a strong function of the observed data sample interval, and hence the time-scale of the observations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 172-183
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  • 59
    Publication Date: 2011-08-17
    Description: The design of a K-band radiometer for use in the microwave weather project is discussed. The major components of the system, such as feedhorn, waveguide switch, and receiver assembly are described. The system will be installed at DSS 13 at Goldstone, California, when completed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Deep Space Network; p 66-69
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  • 60
    Publication Date: 2011-08-17
    Description: The DSN-Mariner Jupiter/Saturn 1977 telecommunications compatibility tests conducted during the periods 15-20 November 1976, 7-16 December 1976 and 5 January 1977, are an ongoing series of engineering level tests to determine the flight-ground interface compatibility and performance characteristics between these two systems.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 16-37
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  • 61
    Publication Date: 2011-08-17
    Description: Existing techniques for the detection of a moving low light level image by a CCD array have required velocity synchronism between the image and the photogenerated charges. This was necessary to prevent blurring during the long duration of charge integration. A new detection scheme is described which causes the image to be convolved with a clock modulation signal as the photocharges are collected. The charge accumulating from each image point will now be spread over many photoelements due to the absence of velocity synchronism, but the output is not blurred in the usual sense. Instead the charge is distributed through the array in a controlled way so that the image can be reconstructed.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 139-144
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  • 62
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    Publication Date: 2011-08-17
    Description: Intensified CCDs (ICCDs) were built and operated. These ICCDs were electrostatically and magnetically-focussed image tubes which use CCDs as anodes. The ICCDs detected single photoelectrons, and have electron gain very near that which was predicted. The first single-pixel pulse-height distributions were presented, and the leakage current was shown to increase as a function of photoelectron irradiation. The advantages and disadvantages of front- and rear-illuminated designs were discussed in light of differing applications requirements.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 101-105
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  • 63
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    Publication Date: 2011-08-17
    Description: Various techniques were developed which enable the CCD (charge coupled device) imaging array user to obtain optimum performance from the device. A CCD video channel was described, and detector-preamplifier interface requirements were examined. A noise model for the system was discussed at length and laboratory data presented and compared to predicted results.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: JPL Conf. on Charge-Coupled Device Technol. and Appls.; p 83-88
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  • 64
    Publication Date: 2011-08-17
    Description: Configurations (two) of the reflector-only assemblies, using different width backup cones, are analyzed for RF boresight direction changes and wind distortions. The wider backup cone is best for minimum weight; however, there is an optimum weight which minimizes the RF boresight errors for a wind load that produces the maximum pitching moment of both configurations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 128-135
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  • 65
    Publication Date: 2011-08-17
    Description: In projected very-long baseline interferometry (VLBI) work a reference point for 64-m antennas is the intersection of the elevation and azimuth axes. A minimum-level effort at DSS 14 to determine the magnitude of the effect of diurnal changes in the temperature of the alidade legs on the height of the elevation axis is described. The thermal expansion between the lowest recorded temperature -3 C (27 F) and the highest, 36 C (97 F), over the period covered was 8.9 mm (0.35 in.).
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 41-44
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  • 66
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    Publication Date: 2011-08-16
    Description: The principles of operation of solid state nondispersive spectrometers are reviewed. Si(Li) is shown to be the preferred nondispersive X-ray spectrometer because of its inherent resolution advantages and its adaptability to the constraints and philosophy of the HEAO-B observatory. A schematic diagram is presented of the geometry of the HEAO-B solid state detector assembly as a block diagram of the primary logic mode of the HEAO-B X-ray spectrometer.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 67
    Publication Date: 2011-08-16
    Description: A coaxial focused CW scanning laser Doppler velocimeter (SLDV) radar equipment applying heterodyne detection at 10.6 microns can measure intensity fluctuations under field conditions. The set includes a 20 W CO2 laser, a coaxial Cassegrainian telescope, standard heterodyne equipment, and a SAW spectrum analyzer with 100 kHz signal resolution. Operation of the equipment and techniques for taking remote measurements are described briefly. Applications to remote measurements of transverse component of wind speed, as a complement to the traditional Doppler method of determining axial velocity, are under study. SLDV equipment has been used in detection, tracking, and measurements of atmospheric turbulence associated with aircraft wing-tip vortices or with dust devils, and in measurement of general atmospheric wind profiles.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Applied Optics; 15; Sept
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  • 68
    Publication Date: 2011-08-16
    Description: The rationale for a Water Vapor Radiometer (WVR) as an aid in predicting tropospheric delay correction is presented. Included is a block diagram and a description of the present developmental WVR with the semiautomated operating sequence outlined. A brief summary of field tests at El Monte airport and Pt. Mugu is given.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Deep Space Network; p 77-84
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  • 69
    Publication Date: 2011-08-16
    Description: The advent of domestic satellite systems and technological improvements in both space and ground equipment makes the use of small aperture earth stations economically feasible and attractive for broadcast satellite applications. With increasing use of the orbit spectrum, there is some concern that broadcast satellite systems may not be able to obtain satisfactory allocations of this orbit-spectrum resource because of interference considerations. Specifically, interference calculations based on the present envelope result in comparatively large orbit spacings for broadcast satellites. Theoretical and experimental investigations of simple sidelobe suppression techniques, plus an analysis of experimental data on small aperture antennas, indicate that much better sidelobe performance can be obtained with a very small cost or performance penalty.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Broadcasting; BC-22; June 197
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  • 70
    Publication Date: 2011-08-16
    Description: The input admittance of the rectangular cavity-backed slot antenna is investigated. The slot is assumed narrow so that the voltage distribution in its aperture is sinusoidal. Equations which represent the input admittance of this slot, backed by a rectangular cavity in which a single propagating wave is assumed to exist, are given. Calculations based on these representations are compared to available measured data. As the depth of the cavity increased the resonant frequency decreased and the bandwidth became narrower. Input admittance curves as a function of electrical slot length are also presented for several size cavities.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-24; May 1976
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  • 71
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    Publication Date: 2011-08-17
    Description: Work with a state-of-the-art high density PCM tape recorder reproducer system is described. The tape recorder is designed for 80 Mb/s operation at an overall bit error rate of .00001and for 40 Mb/s operation at .000001. The article describes the process of measuring the error rate. Also detailed is a data rate buffer designed for use in recent radar experiments and generalizable to most potential uses of the recorder system.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Deep Space Network; p 110-118
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  • 72
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    Publication Date: 2011-08-17
    Description: The X-band feeds in the Deep Space Network were upgraded to include selectable polarization in time for the Voyager missions to the outer planets. The modified antenna feed has the following major items added: two circular waveguide rotary joints, drive motor and gear reducer, gear assembly, two microswitches, and a polarization control junction box. The overall length of the feed remains the same because circular waveguide spacing sections were designed into the original feed to readily permit such modifications. There is no significant increase in antenna noise temperature compared to the original feed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network, Vol. 39; p 177-180
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  • 73
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    Publication Date: 2011-08-17
    Description: An automated antenna pointing subsystem (APS) is being installed at DSS 13 as part of the unattended station project. The function of the APS is to track an instructed position with the 26 meter antenna and to monitor the antenna servo system and meteorological conditions to ensure a proper operational environment. This article discusses the now-completed first phase of the digital hardware portion of the APS development.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 100-109
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  • 74
    Publication Date: 2011-08-17
    Description: A set of measured data on the X-band performance of the three 64-meter deep space stations was obtained for use in future mission telecommunication design and predictions. The test configuration and measurement procedure is described. A method of modelling attenuation due to the atmosphere is given. Radio source brightness temperature and flux density are reviewed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network, Vol. 39; p 76-99
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  • 75
    Publication Date: 2011-08-17
    Description: A systematic study was performed to evaluate the suitability of adhesives for sealing hybrid packages. Selected adhesives were screened on the basis of their ability to seal gold-plated Kovar butterfly-type packages that retain their seal integrity after individual exposures to increasingly severe temperature-humidity environments. Tests were also run using thermal shock, temperature cycling, mechanical shock and temperature aging. The four best adhesives were determined and further tested in a 60 C/98% RH environment and continuously monitored in regard to moisture content. Results are given, however, none of the tested adhesives passed all the tests.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Marshall Space Flight Center Proc. of the 1977 NASA(ISHM Microelectronics Conf.; p 77-94
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  • 76
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    Publication Date: 2011-08-17
    Description: The 26-meter S-X conversion project provides for the conversion of an existing 26-meter S-band subnet to a 34-meter S- and X-band subnet. The subnet chosen for conversion consists of the following stations: DSS 12 near Barstow, DSS 44 in Australia, and DSS 62 in Spain. The main subsystems effected by this project are the antenna mechanical, antenna microwave, and receiver-exciter. In addition to these, there are many project-related electronic equipments that have been added to the existing station equipment. The major subsystems are essentially through the design stage with the antenna mechanical subsystem completed through detail design with procurement in process.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network, Vol. 39; p 157-167
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  • 77
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    Publication Date: 2011-08-17
    Description: Techniques of combinational algebra and computer simulation are combined to determine the number of weight 22 codewords in the (128,64) BCH code which is being studied for use on future deep-space missions.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network p92-94 (SEE N78-24161 15-12)
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  • 78
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    Publication Date: 2011-08-17
    Description: Modifications of the complex mixer system to increase bandwidth and number of channels were made. Three modified complex mixers were installed at DSS 14 and were used to process planetary radar signals in March and April of 1977.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 88-91
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  • 79
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    Publication Date: 2011-08-17
    Description: The period from 1 July through 31 August 1977 is covered and included is the remainder of post DSN Mark 3 Data Subsystem Implementation Project Viking-related testing at DSS14. Also included are reports on the Viking DSN Discrepancy Reporting System, Viking command support, tracking support, and periodic tests conducted with the Viking spacecraft.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 28-33
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  • 80
    Publication Date: 2011-08-17
    Description: The Voyager Flight Project - DSN Telecommunications Compatibility Test Program consisted of three phases: Subsystem Design, System Design, and System Verification Tests. Subsystem Design Tests were performed during mid 1976. System Design Tests were performed during late 1976 and early 1977. System Verification Tests were performed during the spring and summer of 1977. This article describes the System Design Tests and test results that provided the basis for establishment of telecommunications design between the DSN and the Voyager Flight Project.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 13-27
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  • 81
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    Publication Date: 2011-08-17
    Description: The data system created to collect the functions performed by the Deep Space Network in support of spacecraft radio science experiments is described. Some of the major functional requirements presently being considered for the system are delineated.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network, Vol. 39; p 119-129
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  • 82
    Publication Date: 2011-08-17
    Description: A 15,690-ton commercial container ship was selected as lead ship for an onboard electromagnetic-interference (EMI) survey prior to installation of 1535-1645-MHz (L-Band) shipboard terminals for communication via a maritime satellite. In general, the EMI survey revealed tolerable interference levels on board ship. Radiometer measurements indicate antenna-noise temperatures less than 70 K at elevation angles of 5 deg and greater at 1559 MHz at the output terminals of the 1.2-m diameter parabolic-dish antenna for the L-band shipboard terminal. Other EMI measurements include field intensity from 3-cm and 10-cm wavelength pulse radars, and conducted-emission tests of primary power lines to both onboard radars.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Electromagnetic Compatibility; EMC-19; Nov. 197
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  • 83
    Publication Date: 2011-08-16
    Description: An in situ fracture device for Auger spectroscopy is described. The device is designed to handle small tensile specimens or small double-cantilever beam specimens and is fully instrumented with load and displacement transducers so that quantitative stress-strain measurements can be made directly. Some initial test results for specimens made from 4130 and 1020 steel are presented. Results indicate that impurity segregation at interfaces other than grain boundary may play a significant role in the mechanism of ductile fracture.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Review of Scientific Instruments; 47; Apr. 197
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  • 84
    Publication Date: 2011-08-17
    Description: A third-generation S-band radiometer has been calibrated at intervals over 3.5 years. The built-in stabilization concepts have proven to be very effective. In spite of some nonideal conditions (on runway, in wind, and in rain), an rms value of 0.7-K calibration repeatability has been observed with an average temperature deviation (bias error) of 0.03 K.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: IEEE Transactions on Microwave Theory and Techniques; MTT-25; Oct. 197
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  • 85
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    In:  Other Sources
    Publication Date: 2011-08-17
    Description: A variety of programs have been conducted within EPA to evaluate the capability of various ground-based remote-sensing techniques for measuring the SO2 concentration, velocity, and opacity of effluents from coal-burning power plants. The results of the remote measurements were compared with the results of instack measurements made using EPA reference methods. Attention is given to infrared gas-filter correlation radiometry for SO2 concentration, Fourier-transform infrared spectroscopy for SO2 concentration, ultraviolet matched-filter correlation spectroscopy for SO2 concentration, infrared and ultraviolet television for velocity and SO2 concentration, infrared laser-Doppler velocimetry for plume velocity, and visible laser radar for plume opacity.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Environmental Science and Technology; 11; Oct. 197
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  • 86
    Publication Date: 2011-08-16
    Description: Reflector-antenna calculations using idealised truncated feed patterns can lead to incorrect values of total secondary radiated power. It is demonstrated that this discrepancy is due to the presence of higher-order spherical modes incident on the reflector. When a proper spherical-wave expansion of the incident field is used, in conjunction with the physical-optics technique, to determine the scattered field, the total power of the scattered field will equal the power radiated by the feed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Electronics Letters; 12; Mar. 18
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  • 87
    Publication Date: 2011-08-16
    Description: The factors determining the sensitivity of a real astronomical heterodyne spectrometer are described. The deviation from the ideal heterodyne system for line detection is described in terms of a series of degradation factors. A discussion of degradation due to a low local oscillator power and to line profile detection is presented. Representative values for the degradation factors are given. Even with a total degradation of not less than 30, the heterodyne spectrometer is still found to be a highly sensitive tool in IR astronomy.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 88
    Publication Date: 2011-08-16
    Description: The performance of an upconversion system is examined for observation of astronomical sources in the low to middle IR spectral range. Theoretical values for the performance parameters of an upconversion system for astronomical observations are evaluated in terms of the conversion efficiencies, spectral resolution, field of view minimum detectable source brightness, and source flux. Experimental results of blackbody measurements and molecular absorption-spectrum measurements using a lithium niobate upconverter with an argon-ion laser as the pump are presented. Estimates are given of the expected optimum sensitivity of an upconversion device that may be built with presently available components.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Applied Optics; 15; Apr. 197
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  • 89
    Publication Date: 2011-08-16
    Description: Starting with the 1960 Delta launch of the first Echo satellite, NASA's Goddard Space Flight Center (GSFC) became one of the pioneers in satellite communications. Attention is given to the project Syncom, the Applications Technology Satellite (ATS) program, the ATS-6 project, and current GSFC efforts. After the decision announced in January of 1973 that NASA would phase out of communications satellite programs, the communications effort at GSFC concentrates on the operation of ATS spacecraft in orbit, experiments in the 12- to 14 GHz frequency band, and advanced communications research.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Signal; 30; Mar. 197
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  • 90
    Publication Date: 2011-08-16
    Description: Black body measurements and absorption spectra of methane near 3.3 microns are presented and used as examples in a discussion of upconversion spectrometry for astrophysical application. Factors determining the system conversion efficiency and the minimum detectable flux for a typical system are presented. The spectrometer described uses an Argon-ion laser and a temperature turned LiNbO3 crystal in a CW mode. Satisfactory agreement between measured and calculated performance parameters is obtained. An estimate of the highest performance parameters attainable using current technology is given.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 91
    Publication Date: 2011-08-16
    Description: A real-time digital video processor using Hadamard transform techniques to reduce video bandwidth is described. The processor can be programmed with different parameters to investigate various algorithms for bandwidth compression. The processor is also adaptive in that it can select different parameter sets to tradeoff spatial resolution for temporal resolution in the regions of the picture that are moving. Algorithms used in programming the system are described along with results achieved at various levels of compression. The algorithms relate to spatial compression, temporal compression, and the adaptive selection of parameter sets.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Electromagnetic Compatibility; EMC-18; Feb. 197
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  • 92
    Publication Date: 2011-08-16
    Description: Experiments were carried out to evaluate the effects of normal velocity gradients on hot wire measurements in a subsonic boundary layer of the same size as the flow investigated by Johnson and Rose (1975). Both hot wire and film anemometers were used to measure the turbulent properties of the boundary layer. A special X-wire probe with one wire vertical and the other at an angle of about 40 deg to the flow was used to demonstrate the gradient effects. The results indicate that major errors are encountered when mean and turbulent velocity gradients exist along the length of hot wire sensors, the problem being more pronounced at high speeds. Although the split film sensor results show a significant improvement over the X-wire sensor, further reduction in the space resolution of sensors by roughly an order of magnitude would appear to be necessary to reduce the error to acceptable values near the wall.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: AIAA Journal; 14; Mar. 197
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  • 93
    Publication Date: 2011-08-17
    Description: Preparation is being made by the DSN to monitor the stability of its clocks and frequency standards in the 64 meter net by means of VLBI. Since variations in the earth's rotation rate represent an error source to VLBI clock synchronization, the Allan Variance of the earth rotation was calculated to find that, in a long-term sense at least, these variations do not noticeably increase the differential instability of two clocks as measured by Intercontinental VLBI.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: The Deep Space Network; p 81-84
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  • 94
    Publication Date: 2011-08-17
    Description: Very Long Baseline Interferometry (VLBI) is a method for observation of extragalactic radio sources which appears to have potential for precise long-distance earth surveying, clock synchronization and spacecraft navigation. Many researchers have been working to establish the accuracy of VLBI observations. The intent of the work reported here is to review the principal components of the VLBI instrument in order to estimate and/or bound the systematic error contributions. In this first of a series of articles, the definitions and tools which are needed in order to apply filter transfer-function analysis to the VLBI receiver are established and they are used to estimate the sensitivity of the VLBI receiver to plausible filter variations.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 54-80
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  • 95
    Publication Date: 2011-08-18
    Description: A set of standard formatting rules for the data sets, and a standard computer-readable language with which to describe the data, are two tools which are used to create the Standard Format Data Unit (SFDU). The NASA/JPL proposal for creation and utilization of SFDUs is presented, and its relationship to recommendations from the Consultative Committee for Space Data Systems (CCSDS) is discussed. Several current and planned implementations of the SFDU concept among major space flight projects are identified. The purpose of creating the concept of an SFDU is to allow members of the science community to share national and global resource data independently of project or program. The feedback from SFDU implementation efforts is considered an essential part of the CCSDS activity. Even though the CCSDS specifically deals with space data systems, the SFDU concept can be applied to practically every data system on an open network. The SFDU is in the early phase of CCSDS standard definition work, and must go through several other phases before being formally recommended as an international standard.
    Keywords: COMMUNICATIONS AND RADAR
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  • 96
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    In:  Other Sources
    Publication Date: 2011-08-18
    Description: The design and performance of the high-density digital recorder (HDDR) developed for use at the NASA centers (KSC, JSC, and GSFC) and at the JPL to store and retrieve 50-Mb/s PCM data streams from the Spacelab experiments are reported. The recording reproduction, and transport requirements are reviewed; and the design solutions adopted in the final version of the HDDR are described, incuding three-position-modulation and Y-phase encoding, microprocessor-controlled automatic bit synchronization and equalization, cyclic-redundancy-check error detection and correction, clock regeneration, data and clock variations, tape-speed control, and EEE-488 remote control. Reliable performance, with bit error rates 1 in 10 to the 10th forward and 1 in 10 to the 9th reverse or better and packing density up to 50 percent greater than that obtainable using conventional codes, is reported after 1.5 years of service.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 97
    Publication Date: 2011-08-18
    Description: To support the development of advanced infrared remote sensing instrumentation using line and area arrays, a test facility has been developed to characterize the detectors. The necessary performance characteristics of the facility were defined by considering current and projected requirements for detector testing. The completed facility provides the desired level of detector testing capability as well as providing ease of human interaction.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 98
    Publication Date: 2011-08-18
    Description: Two comparisons of available specular infrared measurements using identical or very similar coatings reveal that specular BRDF (bidirectional reflectance distribution function) measurements of rough coatings are comparable but that simple measured reflectances are not. This is seen as indicating that the diffuse component of the measured specular reflectance is significantly larger than that of the specular component. It is noted that the diffuse component of the measurement is a convolution of the intrinsic directional reflectivity of the surface with the instrument function and that because the value of that function increases at the wavelengths under consideration, the diffuse component is larger than would otherwise be expected. The BRDF normalization is found to cause a primitive deconvolution of the instrument function and to produce a quantity that is approximately equal to the mean intrinsic directional reflectivity very near the specular direction. The analysis and comparison of data reveal that nonspecular BRDF measurements at angles well outside the instrument function can be calibrated as well by an image of the source upon the detector as by reference to a known surface.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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  • 99
    Publication Date: 2011-08-18
    Description: Simple, practical methods for damping reflector vibrations and designing antenna-feed attitude control systems in large deployable spaceborne antennas are proposed. The former involves a movable damper which is positioned so that the rate-of-change of total vibrational energy is minimized. The latter introduces a mechanical decoupler between the flexible boom and the antenna-feed, whereby the feed-attitude control system can be designed independent of boom dynamics. The validity of these approaches are substantiated by analytical studies, computer simulation, and experimental studies.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Proc. of the Workshop on Appl. of Distributed System Theory to the Control of Large Space Struct.; p 143-161
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  • 100
    Publication Date: 2011-08-18
    Description: An analysis is presented of the accuracy of infrared differential absorption lidar (DIAL) measurements of trace constituents in the atmosphere. Expressions are derived for the signal-to-noise ratios applicable in the detection of a signal from a scattering cell for the cases of single-detection heterodyne detection and direct detection. Results of computer simulations of the expectation value of the measured return for various measurement conditions are presented which illustrate the sensitivities of plume measurements for horizontal range-resolved and vertical content measurements of NH3 in heterodyne and direct detection. Advantages for long-range measurements of the use of rare isotope laser frequencies, tuning by collision broadening, and closely spaced on and off frequencies are pointed out.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
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