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  • AIRCRAFT PROPULSION AND POWER  (765)
  • COMMUNICATIONS AND RADAR
  • 1980-1984  (425)
  • 1975-1979  (913)
  • 1950-1954
  • 1980  (425)
  • 1977  (507)
  • 1976  (406)
Collection
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  • 1980-1984  (425)
  • 1975-1979  (913)
  • 1950-1954
Year
  • 1
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    Aircraft engines (1977)
    In:  CASI
    Details
    Publication Date: 2006-01-16
    Description: Thrust and weight requirements of aircraft engines in general are discussed. The characteristics and operating principles of various types of air breathing and rocket engines are described.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Soviet Aircraft and Rockets (NASA-TT-F-770); p 81-139
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  • 2
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    A radio lens in the ionosphere (1977)
    In:  Other Sources
    Details
    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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  • 3
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    Limitations on oceanographic use of beam-limited target-referenced radars (1977)
    In:  Other Sources
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    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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  • 4
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    Tracking performance of symbol synchronizers for Manchester coded data (1977)
    In:  Other Sources
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    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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  • 5
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    An antenna for limited scan in one plane - Design criteria and numerical simulation (1977)
    In:  Other Sources
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    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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  • 6
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    Optimum performance of suppressed carrier receivers with Costas loop tracking (1977)
    In:  Other Sources
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    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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  • 7
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    Alias lock behavior of sampled-data Costas loops (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The potential false-lock problem associated with the sampled data type of Costas loop implementation is addressed in this paper. The term 'alias lock' is used here to differentiate this type of false lock behavior from the data sideband false lock behavior of analog Costas loops. It is shown that the sampled-data version of the conventional Costas loop, sampled at a rate 1/T(s), can alias lock at frequencies that are multiples of 1/2T(s) away from the carrier frequency. It is also shown that the alias lock problem of the sampled data version of the Costas loop with hard-limited in-phase channel is further compounded by the potential occurrence of false lock frequencies at rational multiples of 1/2T(s) away from the carrier. The false lock S-curves of I-Q loops and decision-directed I-Q loops are investigated in detail, with and without additive noise. Close agreement between theory and earlier experimental results is also demonstrated.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-28; Aug. 198
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  • 8
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    Comparison of three-phase modulation with two-phase and four-phase modulation (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: For a constant added noise density at high signal-to-noise ratios and for the same error rate, three-phase PSK requires about 0.75 dB less energy per bit than two-phase or four-phase PSK. However, at very low signal-to-noise ratios, three-phase PSK requires about 0.74 dB more energy per bit of channel capacity than two-phase or four-phase PSK.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-28; July 198
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  • 9
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    Multiple scattering effects on wave propagation due to rain (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The paper examines the multiple scattering of microwaves due to rain and the resulting incoherent intensity for a plane wave incident on a plane-parallel rain region. General formulations of the transfer equation using Stokes parameters are presented, and an extinction matrix which takes into account depolarization effects and nonspherical droplet shape is introduced. Scattering characteristics are calculated for spherical droplets using the Mie solution and the Laws-Parsons distributions. The ratios of incoherent to coherent received powers are calculated at 30 GHz for rain rates of 12.5, 50, 100, and 150 mm/h, rain thicknesses of 3 km and 10 km, and fields of view of 1.5, 5, and 15 deg.
    Keywords: COMMUNICATIONS AND RADAR
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  • 10
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    Prediction of attenuation by rain (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A new model is presented for the prediction of attenuation by rain on either terrestrial or slant earth-to-space propagation paths. The model was developed using geophysical observations of the statistics of point rain rate, of the horizontal structure of rainfall, and of the vertical temperature structure of the atmosphere. The model was tested by comparison with attenuation distribution observations. The results show excellent agreement; the observations differ from model predictions by less than the rms deviations predicted by the model.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-28; Sept
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  • 11
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    Refraction of microwave signals by water vapor (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Tropospheric water vapor causes a refractive path length effect which is typically 5-10% of the 'dry' tropospheric effect and as large as several meters at elevation angles below 5 deg. The vertical water vapor profile is quite variable, and measurements of intensive atmospheric parameters such as temperature and humidity limited to the surface do not adequately predict the refractive effect. It is suggested that a water vapor refraction model that is a function of the amount of precipitable water alone can be successful at low elevation angles. From an extensive study of numerical ray tracings through radiosonde balloon data, such a model has been constructed. The model predicts the effect at all latitudes and elevation angles between 2 and 10 deg to an accuracy of better than 4% (11 cm at 3 deg elevation angle).
    Keywords: COMMUNICATIONS AND RADAR
    Type: Journal of Geophysical Research; 85; Sept. 20
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  • 12
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    Streamtube analysis of a hydrogen-burning scramjet exhaust and simulation technique (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A scramjet/airframe integration program and a technique for simulating thermally perfect scramjet exhaust flows (freon/argon gas blends) is studied to extend the technique to more complicated flows approaching the actual exhaust flow in complexity. The state of the flow and the accuracy of the substitute gas simulation are analyzed in the case of a shock discontinuity present. Findings are: scramjet exhaust flow is essentially frozen throughout the expansion at Mach 6 and Mach 8; flow behind moderate shocks remains frozen; the technique can accurately track static distributions in scramjet exhaust flows (shocked or unshocked).
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Journal of Aircraft; 14; Sept
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  • 13
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    Optimum design and performance of Costas receivers containing soft bandpass limiters (1977)
    In:  Other Sources
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    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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  • 14
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    Polarization loss of a satellite - Data collection sensor link (1977)
    In:  Other Sources
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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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  • 15
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    The Communications Technology Satellite /CTS/ Program (1976)
    In:  Other Sources
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    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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  • 16
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    Analysis of a discrete spectrum analyzer for the detection of radio frequency interference (1977)
    In:  Other Sources
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    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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  • 17
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    Walsh transforms and signal detection (1977)
    In:  Other Sources
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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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  • 18
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    Radio frequency interference from near-earth satellites (1977)
    In:  Other Sources
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    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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  • 19
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    Television applications of interline-transfer CCD arrays (1976)
    In:  Other Sources
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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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  • 20
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    Television cameras employing solid-state imaging sensors for manned spacecraft applications (1976)
    In:  Other Sources
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    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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  • 21
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    Command detector SNR estimator and lock status monitor circuitry (1976)
    In:  Other Sources
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    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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  • 22
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    The scattering of obliquely incident plane waves from a corrugated conducting surface (1976)
    In:  Other Sources
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    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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  • 23
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    Modification of the DSN radio frequency angular tropospheric refraction model (1977)
    In:  Other Sources
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    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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  • 24
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    Synchronization strategies for RFI channels (1977)
    In:  Other Sources
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    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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  • 25
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    Proportionality between Doppler noise and integrated signal path electron density validated by differenced S-X range (1977)
    In:  Other Sources
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    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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  • 26
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    The Deep Space Network-Mariner Jupiter/Saturn 1977 flight project telecommunications compatibility (1977)
    In:  Other Sources
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    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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  • 27
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    Radio frequency boresight analysis of the low cost 64-meter antenna (1976)
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    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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  • 28
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    Magnitude of 64-m elevation axis movements due to alidade temperature changes (1976)
    In:  Other Sources
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    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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  • 29
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    Remote intensity fluctuation measurements with a laser Doppler radar (1976)
    In:  Other Sources
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    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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  • 30
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    New sidelobe envelopes for small aperture earth stations (1976)
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    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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  • 31
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    The input admittance of the rectangular cavity-backed slot antenna (1976)
    In:  Other Sources
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    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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  • 32
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    Selectable polarization at X-band (1977)
    In:  Other Sources
    Details
    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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    DSS 13 automated antenna pointing subsystem phase 1 hardware (1977)
    In:  Other Sources
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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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  • 34
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    X-band antenna gain and system noise temperature of 64-meter deep space stations (1977)
    In:  Other Sources
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    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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  • 35
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    Investigation of package sealing using organic adhesives (1977)
    In:  Other Sources
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    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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  • 36
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    The 26-meter S-X Conversion Project (1977)
    In:  Other Sources
    Details
    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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  • 37
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    Minimum-weight codewords in the (128,64) BCH (1977)
    In:  Other Sources
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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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  • 38
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    Complex mixer system modifications (1977)
    In:  Other Sources
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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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  • 39
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    Viking extended mission support (1977)
    In:  Other Sources
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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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  • 40
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    Voyager flight project: DSN Telecommunications Compatibility Test Program (1977)
    In:  Other Sources
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    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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  • 41
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    DSN radio science system description and requirements (1977)
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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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  • 42
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    EMI survey for maritime satellite 1535-1645-MHz shipboard terminal (1977)
    In:  Other Sources
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    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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  • 43
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    Power conservation for reflector antennas with truncated feed patterns (1976)
    In:  Other Sources
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    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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  • 44
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    Satellite communications at the Goddard Space Flight Center (1976)
    In:  Other Sources
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    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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  • 45
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    Real-time video compression algorithm for Hadamard transform processing (1976)
    In:  Other Sources
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    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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  • 46
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    VLBI (Very Long Baseline Interferometry) instrumental effects, part 1 (1977)
    In:  Other Sources
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    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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  • 47
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    Statistical assessment of speech system performance (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Methods for the normalization of performance tests results of speech recognition systems are presented. Technological accomplishments in speech recognition systems, as well as planned research activities are described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 265-284
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  • 48
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    The Army word recognition system (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The application of speech recognition technology in the Army command and control area is presented. The problems associated with this program are described as well as as its relevance in terms of the man/machine interactions, voice inflexions, and the amount of training needed to interact with and utilize the automated system.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 207-215
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  • 49
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    Speech systems research at Texas Instruments (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: An assessment of automatic speech processing technology is presented. Fundamental problems in the development and the deployment of automatic speech processing systems are defined and a technology forecast for speech systems is presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 289-299
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  • 50
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    Automatic speech recognition research at NASA-Ames Research Center (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A trainable acoustic pattern recognizer manufactured by Scope Electronics is presented. The voice command system VCS encodes speech by sampling 16 bandpass filters with center frequencies in the range from 200 to 5000 Hz. Variations in speaking rate are compensated for by a compression algorithm that subdivides each utterance into eight subintervals in such a way that the amount of spectral change within each subinterval is the same. The recorded filter values within each subinterval are then reduced to a 15-bit representation, giving a 120-bit encoding for each utterance. The VCS incorporates a simple recognition algorithm that utilizes five training samples of each word in a vocabulary of up to 24 words. The recognition rate of approximately 85 percent correct for untrained speakers and 94 percent correct for trained speakers was not considered adequate for flight systems use. Therefore, the built-in recognition algorithm was disabled, and the VCS was modified to transmit 120-bit encodings to an external computer for recognition.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 143-170
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  • 51
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    Multi-user real time word recognition system (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Technological accomplishments in speech recognition systems are presented. A discrete word recognition system which contains an audio spectrum analyzer is described in detail.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 301-304
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  • 52
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    Practical applications of interactive voice technologies: Some accomplishments and prospects (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A technology assessment of the application of computers and electronics to complex systems is presented. Three existing systems which utilize voice technology (speech recognition and speech generation) are described. Future directions in voice technology are also described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 217-234
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  • 53
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    Automatic speech recognition technology development at ITT Defense Communications Division (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An assessment of the applications of automatic speech recognition to defense communication systems is presented. Future research efforts include investigations into the following areas: (1) dynamic programming; (2) recognition of speech degraded by noise; (3) speaker independent recognition; (4) large vocabulary recognition; (5) word spotting and continuous speech recognition; and (6) isolated word recognition.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 305-316
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  • 54
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    Frequencies above 10 GHz (1976)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The paper discusses some of the problems associated with extending the frequencies used by satellite communication services above 10 GHz. The principal propagation limitation above 10 GHz occurs when precipitation intercepts the earth-space propagation path and causes attenuation and depolarization of the transmitted signal. World attenuation statistics at 12 GHz for earth-space paths are discussed, revealing the effect of climate on attenuation properties. Space diversity is discussed as an effective means of overcoming precipitation-caused attenuation problems.
    Keywords: COMMUNICATIONS AND RADAR
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  • 55
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    Aeroacoustics: Jet noise, combustion and core engine noise (1976)
    In:  Other Sources
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    Publication Date: 2011-08-16
    Description: The papers in this volume deal essentially with the question whether the amplification of noise is due to the jet noise phenomenon or perhaps an interaction of airframe and core engine noise. In the area of jet noise suppression, various promising suppressor concepts are examined. The swirling flow jet noise suppressor is shown to provide significant noise reduction with minimal thrust losses. Progress in the aircraft engine core noise problem is reflected by seven research-type papers. Two possible mechanisms are seen to be responsible for core noise. One is the direct noise radiated from the turbulent combustion in the primary combuster and transmitted through the turbine, passing out the nozzle into the far field. The other mechanism is the noise that is emitted from hot spots being convected through the turbine. Which of these mechanisms (or perhaps both mechanisms) is responsible for core noise, and what are the coupling mechanisms of core engine noise and jet noise are the questions confronting researchers.
    Keywords: AIRCRAFT PROPULSION AND POWER
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  • 56
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    How good is jet lift VTOL technology (1977)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The status of technologies for jet-lift V/STOL aircraft is examined, and a critical review of the performance of jet-lift VTOL aircraft built to date is made. Most jet-lift aircraft have suffered from adverse propulsion-induced effects during takeoff and landing. Flight dynamics of jet-lift aircraft have suffered from shortcomings in static and dynamic stability, control characteristics, and flight path control. Some of the main problems to be considered during the selection of a propulsion system arrangement for a V/STOL fighter are discussed. At present, experimental and analytical data on supersonic V/STOL configurations are insufficient to permit evaluating propulsion system arrangements.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Astronautics and Aeronautics; 15; Dec. 197
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  • 57
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    An analysis technique for microstrip antennas (1977)
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    Publication Date: 2011-08-17
    Description: The paper presents a combined numerical and empirical approach to the analysis of microstrip antennas over a wide range of frequencies. The method involves representing the antenna by a fine wire grid immersed in a dielectric medium and then using Richmond's reaction formulation (1974) to evaluate the piecewise sinusoidal currents on the grid segments. The calculated results are then modified to account for the finite dielectric discontinuity. The method is applied to round and square microstrip antennas.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-25; Nov. 197
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  • 58
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    S-X conversion for the block 3 receiver--exciter (1977)
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    Publication Date: 2011-08-17
    Description: An S-X conversion modification was designed for the Block 3 receiver-exciter to be used in the 26 meter S-X Conversion Project. The description, design, specifications, and data are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 141-148
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  • 59
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    CCIR papers on telecommunications for deep space research (1977)
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    Publication Date: 2011-08-17
    Description: A brief description is given of United States participation in the process of developing the technical basis for international allocation and regulation of the radio frequency spectrum. The telecommunication requirements for deep space research are considered. Topics include functional requirements, methods and techniques, and equipment characteristics.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 162-183
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  • 60
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    Dual coupler configuration at DSS 14 for the Voyager era (1977)
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    Publication Date: 2011-08-17
    Description: A description is given of the dual coupler configuration which was installed at DSS 14 for station delay calibrations during the Voyager era. The Z correction values determined for these new and previous configurations are presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Deep Space Network; p 184-192
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  • 61
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    Analysis of the radiation patterns of reflector antennas (1976)
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    Publication Date: 2011-08-16
    Description: The development and application of a numerical technique for rapid calculation of the far-field radiation patterns of a reflector antenna from either a measured or computed feed pattern are reported. The reflector is defined by the intersection of a cone with any surface of revolution or an offset sector of any surface of revolution. The feed is assumed to be linearly polarized and can have an arbitrary location. Both the copolarized and the cross-polarized reflector radiation patterns are computed. Calculations using the technique compare closely with measured radiation patterns of a waveguide-fed offset parabolic reflector. Unique features of this technique are freedom from restrictive feed assumptions and the numerical methods used in preparing the aperture-plane electric-field data for integration.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Antennas and Propagation; AP-24; Jan. 197
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  • 62
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    Effect of endwall cooling on secondary flows in turbine stator vanes (1977)
    In:  CASI
    Details
    Publication Date: 2012-05-19
    Description: An experimental investigation was performed to determine the effect of endwall cooling on the secondary flow behavior and the aerodynamic performance of a coreturbine stator vane. The investigation was conducted in a cold-air, full-annular cascade, where three-dimensional effects could be obtained. Two endwall cooling configurations were tested. In the first configuration, the cooling holes were oriented so that the coolant was injected in line with the inviscid streamline direction. In the second configuration, the coolant was injected at an angle of 15 deg to the inviscid streamline direction and oriented toward the vane pressure surface. In both cases the stator vanes were solid and uncooled so that the effect of endwall cooling could be obtained directly. Total-pressure surveys were taken downstream of the stator vanes over a range of cooling flows at the design, mean-radius, critical velocity ratio of 0.778. Changes in the total-pressure contours downstream of the vanes were used to obtain the effect of endwall cooling on the secondary flows in the stator. Comparisons were made between the two cooled-endwall configurations and with the results obtained previously for solid endwalls.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AGARD Secondary Flows in Turbomachines; 29 p
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  • 63
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    The 1977 WARC on broadcasting satellites - Spectrum management aspects and implications (1977)
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    Publication Date: 2011-08-17
    Description: Broadcasting satellites are allocated as a primary service in the band 11.7-12.2 GHz (11.7-12.5 GHz in Europe, Africa, and the USSR), but the band is also allocated on a primary basis (equal sharing) to other services - fixed, mobile, broadcasting, and fixed satellite. Presented with these difficult sharing situations, delegates from over 100 countries met at an ITU World Administrative Radio Conference in 1977 to develop a plan for broadcasting satellites. Many nations wanted a plan that would assign to them now, reserved orbital locations and channel asignments for their future use. Other countries wanted a plan adopted now for future broadcasting satellites which assigned specific channels to specific areas on the ground so that they could use the remaining frequencies to provide terrestrial service right away. This paper describes the 'Plan' developed at the conference and points out how the principles of spectrum management were employed. It also discusses the implications for future international management of the spectrum growing out of this meeting.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Electromagnetic Compatibility; EMC-19; Aug. 197
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  • 64
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    Preparing aircraft propulsion for a new era in energy and the environment (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Improving fuel efficiency, new sources of jet fuel, and noise and emission control are subjects of NASA's aeronautics program. Projects aimed at attaining a 5% fuel savings for existing engines and a 13-22% savings for the next generation of turbofan engines using advanced components, and establishing a basis for turboprop-powered commercial air transports with 30-40% savings over conventional turbofan aircraft at comparable speeds and altitudes, are discussed. Fuel sources are considered in terms of reduced hydrogen and higher aromatic contents and resultant higher liner temperatures, and attention is given to lean burning, improved fuel atomization, higher freezing-point fuel, and deriving jet fuel from shale oil or coal. Noise sources including the fan, turbine, combustion process, and flow over internal struts, and attenuation using acoustic treatment, are discussed, while near-term reduction of polluting gaseous emissions at both low and high power, and far-term defining of the minimum gaseous-pollutant levels possible from turbine engines are also under study.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Astronautics and Aeronautics; 18; Jan. 198
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  • 65
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    Power line anomalies as they affect the operation of a DSN station: Overview (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The problem of providing a sufficiently stable and reliable power source for the equipment in a DSN station is addressed. The potential for the occurrence of damaging commercial power variations is considered with respect to the need for a more precise power source.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 110-113
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  • 66
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    Feasibility and cost study on VOIR SAR data transfer via a bent pipe link (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An INTELSAT/DOMSAT double hop bent pipe link for the Venus orbiting imaging radar synthetic aperture radar imaging data transfer from deep space stations 43 and 63 to the Jet Propulsion Laboratory was investigated. The cost for the bent pipe transfer was estimated and compared to that for the planned tape record/airfreight-the-tape transfer method.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 82-90
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    Concerning the feasibility of a real time SAR digital processor for VOIR low resolution imaging modes (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The feasibility of real time digital processing of synthetic aperture radar data for Venus orbiting imaging radar low resolution modes was investigated. First, it is shown that range migration is not a problem for these modes. Then, under the assumption of no range migration, fast Fourier transform implementations for accomplishing both range and azimuth correlation in real time are shown to be feasible with current technology.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 72-81
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    Use of K sub A-band for radio metric determinations (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The use of K sub A-band to alleviate the radio metric degradation caused by charged particles is discussed. Those aspects of radio metrics which are relevant to the possible future use of K sub A-band deep space to Earth and Earth to deep space links are reviewed. In particular the effects of the Earth ionosphere, troposphere, and solar plasma are examined. It is concluded that, from the standpoint of reducing the harmful effects of charged particles, the use of K sub A-band appears highly desirable. While stability will be a more serious design constraint at K sub A-band than it is at X-band (for example in the ground power amplifier and the spacecraft multiplier stages) this problem is amenable to a state of the art engineering solution.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 59-66
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  • 69
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    The Tidbinbilla interferometer (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: A proposal to operate a two element interferometer using the 64 m and 26 m antennas of the Tidbinbilla Deep Space Station is discussed. The instrument is to be operated as a correlation interferometer, the sine and cosine products being sampled once per second and recorded for later analysis. The receiver systems are currently under development. Preliminary measurements of the delay line and local oscillator systems and the site cables suggest that a phase stability to within about 1 deg should be achievable with temperature control of the receiver packages.
    Keywords: COMMUNICATIONS AND RADAR
    Type: The Telecommun. and Data Acquisition Rept.; p 6-8
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    Comparison of two leading uniform theories of edge diffraction with the exact uniform asymptotic solution (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The diffraction of an arbitrary cylindrical wave by a half-plane has been treated by Rahmat-Samii and Mittra who used a spectral domain approach. In this paper, their exact solution for the total field is expressed in terms of a new integral representation. For large wave number k, two rigorous procedures are described for the exact uniform asymptotic expansion of the total field solution. The uniform expansions obtained are valid in the entire space, including transition regions around the shadow boundaries. The final results are compared with the formulations of two leading uniform theories of edge diffraction, namely, the uniform asymptotic theory and the uniform theory of diffraction. Some unique observations and conclusions are made in relating the two theories.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radio Science; 15; Nov
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    A note on antenna models in a warm isotropic plasma (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The electron-transparent and electron-reflecting models of antennas in a warm isotropic plasma are reexamined. It is shown that a purely electrical treatment of both the models without an explicit use of the boundary condition on electron velocity yields the same results as those previously obtained through an electromechanical treatment. The essential difference between the two models is that for the electron-reflecting model, fields are nonzero only in the exterior region, while for the electron-transparent model, they are nonzero both in the exterior and interior regions of the antenna. This distinction helps in clarifying some misconceptions about these models of antennas in warm isotropic plasma.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radio Science; 15; Nov
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    FFT methods in signal processing of the coal interface detector radar (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The FM radar for the coal interface detector, operating in the frequency band 2 to 4 GHz, is intended for the display of thicknesses between 2 cm and 20 cm. Because of such a short range, the thickness information is contained in the very few lowest spectral components of the output signal. To overcome this inconvenience, the Fourier series of the output signal was augmented to approximate a Fourier integral. This modification in the signal processing resulted in a higher spectral density, which in turn enabled an easier identification of the interface position in the laboratory. The orientation and spacing of the receiving and transmitting antennas is found to have an important influence on the system performance.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 18 p
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  • 73
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    Simulation of orbital radar images (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The operating parameters for spaceborne synthetic aperture imaging radar systems was addressed in the cost effective manner by using simulation techniques. The use of airborne images, Seasat images, and computer simulation were the first computer simulation of spaceborne radar imagery was analyzed for system definition studies. Analysis of the simulation indicates that incidence angles as small as 30 are useful for general terrain geomorphologic analysis.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Radar Geol: An Assessment Rept. of the Radar Geol. Workshop; p 45-63
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  • 74
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    System analysis for millimeter-wave communication satellites (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Research and development needs for millimeter-wave space communication systems are presented. Assumed propagation fade statistics are investigated along with high data rate diversity link and storage. The development of reliable ferrite switches, and high performance receivers and transmitters is discussed, in addition to improved tolerance of dish and lens fabrication for the antennas. The typical cost for using a simplex voice channel via a high capacity 40/50 GHz satellite is presented.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Microwave Journal; 23; Oct. 198
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  • 75
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    The performance of suppressed carrier receivers in a pulsed RFI environment (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: This paper investigates the tracking performance of a Costas loop in the presence of single and multiple in-band pulsed RFI signals and receiver additive noise. It is shown that the loop's tracking performance is very sensitive to the pulse durations of the RFI signals, as well as their repetition rates and peak powers relative to those of the desired signal. The presence of in-band RFI can affect the loop's tracking performance in basically three ways. 1) The loop tracks the composite phase of the RFI instead of the phase of the desired signal when the effective RFI power is greater than that of the signal. 2) When the effective RFI power is not sufficiently large to capture the loop, there still will exist static phase error biases which cause the loop to lock at a phase between that of the desired signal and the composite RFI. 3) There is an increase in the rms phase jitter over the nominal design. These latter two effects degrade the bit error probability performance of the receiver. More significantly, if the nominal loop bandwidth is not designed properly to account for the increase in jitter phenomenon, frequency cycle slipping may result.
    Keywords: COMMUNICATIONS AND RADAR
    Type: IEEE Transactions on Communications; COM-28; May 1980
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    Advanced low-NO(x) combustors for supersonic high-altitude gas turbines (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The impact of gas-turbine-engine-powered aircraft on worldwide pollution was defined within two major areas of contribution. First, the contribution of aircraft to the local air pollution of metropolitan areas and, second, the long-term effects on the chemical balance of the stratosphere of pollutants emitted from future generations of high-altitude, supersonic commercial and military aircraft. Preliminary findings indicate that stratospheric oxides of nitrogen (NOx) emissions may have to be limited to very low levels if, for example, ozone depletion with concomitant increases in sea-level radiation, are to be avoided. Theoretical considerations suggest that (NOx) levels as low as 1.0 gram per kilogram of fuel and less should be attainable from a idealized premixed type of combustor. Experimental rig studies were intended to explore new combustor concepts designed to minimize the formation of (NOx) in aircraft gas turbines and to define their major operational problems and limitations.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 393-415
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  • 77
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    Soot formation in a turbulent swirling flow (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The qualitative understanding of soot formation in simple models of gas turbine primary-zone combustors is summarized. Soot formation in flame radiation and air pollution was investigated. Results are presented, namely: (1) if the fuel is premixed with air in approximately stoichiometric proportions, the sequence of states that a fluid element undergoes as it burns is quite different from the sequence when liquid or vapor fuel is injected into an air-flow; (2) swirling flows, as are typical or swirl-can combustors, when burning, can amplify small aerodynamic disturbances upstream of the swirl vanes; and (3) different fuels form significantly different amounts of soot. Each of these effects makes major changes in the amount of soot formed in a given combustor.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 309-321
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  • 78
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    Pollution reduction technology program for turboprop engines (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The reduction of CO, HC, and smoke emissions while maintaining acceptable NO(x) emissions without affecting fuel consumption, durability, maintainability, and safety was accomplished. Component combustor concept screening directed toward the demonstration of advanced combustor technology required to meet the EPA exhaust emissions standards for class P2 turboprop engines was covered. The combustion system for the Allison 501-D22A engine was used, and three combustor design concepts - reverse flow, prechamber, and staged fuel were evaluated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 125-147
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  • 79
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    Ceramic composite protection for turbine disc bursts (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Ceramic composite turbine disc protection panels for the A300B were developed using armor technology. Analytical predictions for modifying the ballistic projectile armor system were verified by a test program conducted to qualify the rotor containment system. With only a slight change in the areal density of the armor system a more than two-fold increase in kinetic energy protection level was achieved. Thickness of the fiberglass reinforced plastic backing material was increased to achieve an optimum ratio of ceramic thickness to backing thickness for the different ballistic defeat condition.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 277-293
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  • 80
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    Materials and manufacturing processes for increased life/reliability (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Improvements in both quality and durability of disk raw material for both military and commercial engines necessitated an entirely new concept in raw material process control which imposes careful selection, screening and sampling of the basic alloy ingredients, followed by careful monitoring of the melting parameters in all phases of the vacuum melting sequence. Special care is taken to preclude solidification conditions that produce adverse levels of segregation. Melt furnaces are routinely cleaned and inspected for contamination. Ingots are also cleaned and inspected before entering the final melt step.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 347-368
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  • 81
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    Numerical analysis of projectile impact in woven texile structures (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Computer codes were developed for simulating the dynamic fracture and viscoelastic constitutive response due to stress wave interaction and reflections caused by ballistic impact on woven textiles. The method, which was developed for use in the design and analysis of protection devices for personnel armor, has potential for use in studies of rotor blade burst containment at high velocity. Alterations in coding required for burst containment problems are discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Assessment of Technol. for Turbojet Engine Rotor Failures; p 247-260
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  • 82
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    Lightweight engine containment (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Kevlar fabric styles and weaves were studied, as well as methods of application for advanced gas turbine engines. The Kevlar material was subjected to high speed impacts by simple projectiles fired from a rifle, as well as more complex shapes such as fan blades released from gas turbine rotors in a spin pit. Just contained data was developed for a variety of weave and/or application techniques, and a comparative containment weight efficiency was established for Kevlar containment applications. The data generated during these tests is being incorporated into an analytical design system so that blade containment trade-off studies between Kevlar and metal case engine structures can be made. Laboratory tests and engine environment tests were performed to determine the survivability of Kevlar in a gas turbine environment.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 235-245
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  • 83
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    Approaches to rotor fragment protection (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Key airworthiness design criteria considerations for fragment protection as found in various FAA requirements in FAR Parts 25 and 33, and in interpretive 8110 orders are reviewed. The impact of providing aircraft armor in lieu of engine armor for typical three- and four-engine wide bodied transports for protection within the length of the engine case as well as from fragments exiting ahead of the enlet engine inlet flange is assessed. For protection within the length of the engine case, armor weight penalties, plus fuel burned and dollar cost of carrying the armor protection are defined. Immediately ahead of the inlet flange, direct tangential impacts are predominant, but further forward, rebound impacts predominate. Armor thickness requirements and fuel cost impact of protection are given.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 101-103
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  • 84
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    Engine Non-Containment: The UK CAA View (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Airworthiness accidents account for roughly one quarter of the total number of accidents to public transport turbojet aircraft. The most reliable, practicable, and cost-effective means of minimizing damage outside the confines of the nacelle is to make the aircraft design invulnerable to any debris which may affect the aircraft. A failure model was developed for use by aircraft builders in measuring the freedom from catastrophe factor of their design.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 11-32
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  • 85
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    Research on speech understanding and related areas at SRI (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Research capabilities on speech understanding, speech recognition, and voice control are described. Research activities and the activities which involve text input rather than speech are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 45-63
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    Voice integrated systems (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The program at Naval Air Development Center was initiated to determine the desirability of interactive voice systems for use in airborne weapon systems crew stations. A voice recognition and synthesis system (VRAS) was developed and incorporated into a human centrifuge. The speech recognition aspect of VRAS was developed using a voice command system (VCS) developed by Scope Electronics. The speech synthesis capability was supplied by a Votrax, VS-5, speech synthesis unit built by Vocal Interface. The effects of simulated flight on automatic speech recognition were determined by repeated trials in the VRAS-equipped centrifuge. The relationship of vibration, G, O2 mask, mission duration, and cockpit temperature and voice quality was determined. The results showed that: (1) voice quality degrades after 0.5 hours with an O2 mask; (2) voice quality degrades under high vibration; and (3) voice quality degrades under high levels of G. The voice quality studies are summarized. These results were obtained with a baseline of 80 percent recognition accuracy with VCS.
    Keywords: COMMUNICATIONS AND RADAR
    Type: Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 123-140
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  • 87
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    Multi-system approach to speech understanding (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The Harpy and Hearsay-2 systems are described. The performance of these systems was tabulated. The large number of design decisions which confront a speech understanding system are discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 11-23
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  • 88
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    Voice data entry in air traffic control (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Several of the keyboard data languages were tabulated and analyzed. The key language chosen as a test vehicle was that used by the nonradar or flight data controllers. This application was undertaken to minimize effort in a cost efficient way and with less research and development.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 171-196
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  • 89
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    Voice input/output capabilities at Perception Technology Corporation (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Condensed resumes of key company personnel at the Perception Technology Corporation are presented. The staff possesses recognition, speech synthesis, speaker authentication, and language identification. Hardware and software engineers' capabilities are included.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 95-106
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  • 90
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    Voice technology and BBN (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The following research was discussed: (1) speech signal processing; (2) automatic speech recognition; (3) continuous speech understanding; (4) speaker recognition; (5) speech compression; (6) subjective and objective evaluation of speech communication system; (7) measurement of the intelligibility and quality of speech when degraded by noise or other masking stimuli; (8) speech synthesis; (9) instructional aids for second-language learning and for training of the deaf; and (10) investigation of speech correlates of psychological stress. Experimental psychology, control systems, and human factors engineering, which are often relevant to the proper design and operation of speech systems are described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 65-75
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  • 91
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    Real-time interactive speech technology at Threshold Technology, Incorporated (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Basic real-time isolated-word recognition techniques are reviewed. Industrial applications of voice technology are described in chronological order of their development. Future research efforts are also discussed.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 235-261
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  • 92
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    Military applications of automatic speech recognition and future requirements (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: An updated summary of the state-of-the-art of automatic speech recognition and its relevance to military applications is provided. A number of potential systems for military applications are under development. These include: (1) digital narrowband communication systems; (2) automatic speech verification; (3) on-line cartographic processing unit; (4) word recognition for militarized tactical data system; and (5) voice recognition and synthesis for aircraft cockpit.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 197-205
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  • 93
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    Sperry Univac speech communications technology (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Technology and systems for effective verbal communication with computers were developed. A continuous speech recognition system for verbal input, a word spotting system to locate key words in conversational speech, prosodic tools to aid speech analysis, and a prerecorded voice response system for speech output are described.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NADC, Proceedings: Voice Technology for Interactive Real-Time Command(Control Systems Application; p 77-93
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  • 94
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    Effect of ambient temperature and humidity on emissions of an idling gas turbine (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The effects of inlet pressure, temperature, and humidity on the oxides of nitrogen produced by an engine operating at takeoff power setting were investigated and numerous correction factors were formulated. The effect of ambient relative humidity on gas turbine idle emissions was ascertained. Experimentally, a nonvitiating combustor rig was employed to simulate changing combustor inlet conditions as generated by changing ambient conditions. Emissions measurements were made at the combustor exit. For carbon monoxide, a reaction kinetic scheme was applied within each zone of the combustor where initial species concentrations reflected not only local combustor characteristics but also changing ambient conditions.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 437-456
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  • 95
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    Global atmospheric sampling program (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Automated instruments were installed on a commercial B-747 aircraft, during the program, to obtain baseline data and to monitor key atmospheric constituents associated with emissions of aircraft engines in order to determine if aircraft are contributing to pollution of the upper atmosphere. Data thus acquired on a global basis over the commercial air routes for 5 to 10 years will be analyzed. Ozone measurements in the 29,000 to 45,000 foot altitude were expanded over what has been available from ozonesondes. Limited aerosol composition measurements from filter samples show low levels of sulfates and nitrates in the upper troposphere. Recently installed instruments for measurement of carbon monoxide and condensation nuclei are beginning to return data.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 323-355
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  • 96
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    Emissions control for ground power gas turbines (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The similarities and differences of emissions reduction technology for aircraft and ground power gas turbines is described. The capability of this technology to reduce ground power emissions to meet existing and proposed emissions standards is presented and discussed. Those areas where the developing aircraft gas turbine technology may have direct application to ground power and those areas where the needed technology may be unique to the ground power mission are pointed out. Emissions reduction technology varying from simple combustor modifications to the use of advanced combustor concepts, such as catalysis, is described and discussed.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 203-242
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  • 97
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    Pollution reduction technology program for small jet aircraft engines: Class T1 (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Small jet aircraft engines (EPA class T1, turbojet and turbofan engines of less than 35.6 kN thrust) were evaluated with the objective of attaining emissions reduction consistent with performance constraints. Configurations employing the technological advances were screened and developed through full scale rig testing. The most promising approaches in full-scale engine testing were evaluated.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA. Lewis Res. Center Aircraft Eng. Emissions; p 149-180
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    Emissions Reduction Technology Program (1977)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Combustor concepts having the potential for significantly lower emissions levels were investigated. The combustor emissions reduction was measured in an engine test. Emission characteristics common to all engine classes are shown. Multiple-burning zone combustors, specifically the double-annular and swirl-can combustors were studied. Airblast and air-assist fuel injection techniques were evaluated for emissions control potential. The combustor sceening and refining phases are summarized.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: Aircraft Eng. Emissions; p 19-58
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  • 99
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    Qualification model spacecraft tests for DEMP, SGEMP, and ESD effects (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The development of a satellite design demonstration test program is described. The test approach is comprehensive in that it includes the effects from electrostatic discharge (ESD), system generated electromagnetic pulse (SGEMP), as well as dispersed electromagnetic pulses (DEMP). The comprehensive test concept is based on the similarity of the satellite's response to several environments.
    Keywords: COMMUNICATIONS AND RADAR
    Type: NASA. Lewis Res. Center Proc. of the Spacecraft Charging Technol. Conf.; p 815-828
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  • 100
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    Turbine disks for improved reliability (1977)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Advanced disk structural concepts were employed to improve the cyclic lives and reliability of turbine disks. Analytical studies were conducted to evaluate bore-entry disks as potential replacements for the existing first-stage turbine disks in the CF6-50 and JT8D-17 engines. Results of low cycle fatigue, burst, fracture mechanics, and fragment energy analyses are summarized for the advanced disk designs and the existing disk designs, with both conventional and advanced disk materials. Other disk concepts such as composite, laminated, link, multibore, multidisk, and spline disks were also evaluated for the CF6-50 engine.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: MIT An Assessment of Technol. for Turbojet Engine Rotor Failures; p 389-411
    Format: application/pdf
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