A survey of current debugging concepts
Debugging computer programs in terms of localization and correction of errors
Kocher, W.↗
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Space Satellite Dynamics with Applications to Sunlight Pressure Attitude Control
A research program into three aspects of space satellite dynamics was carried out. First, a four-dimensional space-time formulation of Newtonian mechanics is developed. This theory allows a new physical interpretation of the conservation theorems of mechanics first derived rigorously by Noether. Second, a new concept for estimating the three angles which specify the orientation in space of a rigid body is presented. Two separate methods for implementing this concept are discussed, one based on direction cosines, the other on quaternions. Two examples are discussed: constant orientation in space, and constant rate of change of the three angles with time. Third, two synchronous equatorial orbit communication satellite designs which use sunlight pressure to control their attitude are analyzed. Each design is equipped with large reflecting surfaces, called solar sails, which can be canted in different directions to generate torques to correct pointing errors.
Stuck, B. W.↗
Modifications and additions to NASTRAN at Marshall Space Flight Center, 1969 - 1972
Modifications to NASTRAN code which result from the location, identification, and correction of errors or operational problem areas are reviewed. Addition of improved capability which is structural, executive system oriented, or utility in nature is also considered. NASTRAN efficiencies and inefficiencies are studied.
Jordon, A. J., Jr.↗
A system debugging model.
Consideration of the nature of the 'debugging' process applied to a new complex system during the initial period of its life. During this period failures and errors are corrected as they occur, with resulting improvement in the subsequent performance of the system. One mathematical idealization of this process leads to the assumption that system failure rate is decreasing with time. In practice, the debugging phase is considered completed when the failure rate reaches an equilibrium or constant value. Models are formulated for this phenomenon. Maximum likelihood estimates are obtained for relevant failure rate functions and for the end of the debugging period. A conservative upper confidence bound on the stable failure rate is obtained.
Barlow, R. E.↗
SD-4060OCPLT4 program, user's guide
A brief description of the Orbit Comparison Plot (OCPLT4) program is presented, along with user information and a source program listing. In addition to correcting several errors that existed in the original program, this program incorporates the following new features: (1) For any satellite whose observations are processed by the Definitive Orbit Determination System (DODS), the orbital uncertainty estimates (OUE) can be obtained via appropriate card input with no major modification to the program. (2) All satellite-related information (e.g., plotter scales, cutoff limits, plotting frequencies) is user controlled via card input. (3) Not all components of OUE must be obtained. The user has the option of obtaining only the radial component if there is no need for the other two components. (4) The altitude and time graph formats are controlled by the user and are not stored for specific satellites.
Glazer, J.↗
Delta modulation
The overshoot suppression algorithm has been more extensively studied. Computer generated test-pictures show a radical improvement due to the overshoot suppression algorithm. Considering the delta modulator link as a nonlinear digital filter, a formula that relates the minimum rise time that can be handled for given filter parameters and voltage swings has been developed. The settling time has been calculated for the case of overshoot suppression as well as when no suppression is employed. The results indicate a significant decrease in settling time when overshoot suppression is used. An algorithm for correcting channel errors has been developed. It is shown that pulse stuffing PCM words in the DM bit stream results in a significant reduction in error length.
Schilling, D. L.↗
Four-body trajectory optimization
The two methods which are suitable for use in a 4-body trajectory optimization program are both multiconic methods. They include an approach due to Wilson (1970) and to Byrnes and Hooper (1970) and a procedure developed by Stumpff and Weiss (1968). The various steps in a trajectory optimization program are discussed, giving attention to variable step integration, the correction of errors by quadrature formulas, questions of two-impulse transfer, three-impulse transfer, and two examples which illustrate the implementation of the computational approaches.
Pu, C. L.↗
Calculation of autoionization of He and H/-/ using the projection-operator formalism
Improved calculations are reported for the first several autoionization states of the lower symmetries of He and H(-). Unshifted energies are calculated by diagonalizing QHQ using a Hylleraes basis with more terms than previously used; shifts, widths, and photoabsorption shape parameters are obtained with the additional use of exchange-approximate nonresonant continuum functions. Previous calculations of H(-) resonances are reviewed and slightly augmented by applying various nonresonant continua and correcting small errors. A comparison is made between the calculations and experimental results and is found to be very satisfactory except for the lowest 1P autoionization state of He, which is shown to need a more accurate experimental determination.
Bhatia, A. K.↗
A comparison of Skylab S-193 and aircraft views of surface roughness and a look toward SEASAT
An extensive aircraft underflight program was conducted along the Skylab groundpath for the purpose of documenting wind, wave, and atmospheric conditions affecting the amplitude of the active and passive microwave signatures. The S-193 microwave system senses a roughness parameter at the ocean surface that is proportional to the surface windspeed. The aircraft program is described, and some comparisons of satellite and aircraft results are presented. The principal result of the comparison of active radar is that direct inferences of the surface windspeed are possible, but subject to considerable scatter, and that this scatter appears to be due to interaction between long gravity and short Bragg waves and backscatter due to rain as well as errors in correcting for azimuth dependence. An unforeseen opportunity to observe a Pacific hurricane by both Skylab and NOAA aircraft has contributed to the development of a simplified wave forecasting scheme applicable to hurricanes, and more general conditions, which combines the better qualities of both spectral and height/period forecasting techniques. Horizontal polarization data obtained by the aircraft in Hurricane Ava, and in other experiments, which led to this development are presented.
Ross, D.↗
Encoding and decoding a telecommunication standard command code
A simple encoder/decoder implementation scheme is described for the (63,56) BCH code which can be used to correct single errors and to detect any even-number of errors. The scheme is feasible for onboard-spacecraft implementation.
Benjauthrit, B.↗
Flight test evaluation of predicted light aircraft drag, performance, and stability
A technique was developed which permits simultaneous extraction of complete lift, drag, and thrust power curves from time histories of a single aircraft maneuver such as a pullup (from V sub max to V sub stall) and pushover (to sub V max for level flight.) The technique is an extension to non-linear equations of motion of the parameter identification methods of lliff and Taylor and includes provisions for internal data compatibility improvement as well. The technique was show to be capable of correcting random errors in the most sensitive data channel and yielding highly accurate results. This technique was applied to flight data taken on the ATLIT aircraft. The drag and power values obtained from the initial least squares estimate are about 15% less than the 'true' values. If one takes into account the rather dirty wing and fuselage existing at the time of the tests, however, the predictions are reasonably accurate. The steady state lift measurements agree well with the extracted values only for small values of alpha. The predicted value of the lift at alpha = 0 is about 33% below that found in steady state tests while the predicted lift slope is 13% below the steady state value.
Smetana, F. O.↗
Radar error statistics for the space shuttle
Radar error statistics of C-band and S-band that are recommended for use with the groundtracking programs to process space shuttle tracking data are presented. The statistics are divided into two parts: bias error statistics, using the subscript B, and high frequency error statistics, using the subscript q. Bias errors may be slowly varying to constant. High frequency random errors (noise) are rapidly varying and may or may not be correlated from sample to sample. Bias errors were mainly due to hardware defects and to errors in correction for atmospheric refraction effects. High frequency noise was mainly due to hardware and due to atmospheric scintillation. Three types of atmospheric scintillation were identified: horizontal, vertical, and line of sight. This was the first time that horizontal and line of sight scintillations were identified.
Lear, W. M.↗
Liquid content of the lower clouds of Venus as determined from Mariner 10 radio occultation
S- and X-band radio occulation data obtained during the Mariner 10 flyby of Venus are analyzed to determine the effects of signal attenuation due to the clouds of Venus. The signal-amplitude data are corrected for errors introduced by spacecraft motion and antenna steering during the occultation, absorption-coefficient profiles are computed, and the liquid content of the Venusian clouds is estimated. Excess attenuation effects are found and ascribed to absorption by small liquid particles, consisting of a water-sulfuric acid mixture containing 75% + or - 25% sulfuric acid, in the clouds. Three absorbing cloud layers at respective heights of 68, 60, and 48 km are suggested by the X-band absorptivity profile, but only the 68- and 48-km layers are clearly indicated by the S-band profile. The relatively slow S-band absorption at 60 km is tentatively attributed to an unknown constituent that is much more absorbing in the X-band than in the S-band. The results are compared with nephelometer measurements performed at 0.9 micron by the Venera 9 and 10 probes.
Kliore, A. J.↗
Assessment of atmospheric height uncertainties for high precision satellite altimeter missions to monitor ocean currents
The influence of the atmosphere on nadir directed signal associated with satellite altimeters are examined. Frequencies at 6, 13.5, and 35 GHz are selected so as to provide a parameter study. Uncertainties are summarized in both existing and proposed techniques which establish ionospheric and tropospheric height corrections. The error summary thus gives values describing the best you can do in height resolution (as dictated by atmospheric parameters) for a satellite borne altimeter system. The results presented reflect data gleaned from the literature, at large, as well as from the existing body of published literature associated with the Seasat A Altimeter Experiment. Specifically considered are: (1) the effects of precipitation on altimeter signals, (2) range errors due to refractive index variations in both the clear atmosphere (convective and nonconvective) and clouds, and (3) range errors introduced by the ionosphere. A preliminary analysis is pursued establishing the feasibility of incorporating rain rate range gates in a future satellite-borne altimeter system.
Goldhirsh, J.↗
An airborne system for detection of volcanic surface deformations
A technique is proposed for measuring volcanic deformation on the order of centimeters per day to centimeters per year. An airborne multifrequency pulsed radar, tracking passive ground reflectors spaced at 1 kilometer intervals over a 50 square kilometer area is employed. Identification of targets is accomplished by Doppler and range resolution techniques, with final relative position measurements accomplished by phase comparison of multifrequency signals. Atmospheric path length errors are corrected by an airborne refractometer, meteorological instruments, or other refractive index measuring devices. Anticipated system accuracy is 1-2 cm, with measuring times on the order of minutes. Potential problems exist in the high intrinsic data assimilation rate required of the system to overcome ground backscatter noise.
Lunine, J.↗
VAS Demonstration Sounding Workshop: The Proceedings of a satellite sounding workshop
Retrieval techniques that yield satellite derived temperature and moisture profiles are considered, with emphasis on TIROS-N and VISSR atmospheric sounder measurements. Topics covered include operational sounding, colocation concepts, correcting cloud errors, and the First GARP Global Experiment.
Endres, D. L.↗
Ultraviolet spectroscopy of comets
The advantages of the space shuttle being used as an observing platform with advanced instrumentation for the study of comets are discussed. The ground-based observations of the comet West (1976) were used to illustrate the many problems caused by the Earth's atmosphere. The spectrum of comet Bennett (1970 II) was compared to that the of comet West in order to correct instrument errors.
Lillie, C. F.↗
Radiative transfer in cometary dust atmospheres: Critique of recent developments
The gas and dust production rates of comets near the sun are intimately linked to the fate of the solar radiation as it is scattered and partially absorbed by the cometary dust envelope or halo surrounding the comet's nucleus. The radiation of nuclear matter (mostly water ice) and the release of dust particles embedded in the ice which are entrained by the escaping gas and subsequently form a dust atmosphere or halo. On the other hand, the interaction of the dust cloud with the solar radiation is in turn responsible for the amount of radiative energy received by the nucleus and thus determines the evaporation rate. It is shown that recent attempts to formulate this problem quantitatively are in error. The correct formulation is given and it is pointed out that negative extinction (enhancement of the primary radiation received by the nucleus due to multiple scattering) may not be as large as predicted.
Vonroos, O.↗