Digital command system second-order subcarrier tracking loop performance.
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Holmes, J. K.↗
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Dynamic simulation of LEM docking with Apollo command module in lunar orbit
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Hatch, H. G., Jr.↗
Two-carrier command modulation system
Two carriers transmit two high-power signals from single transmitter, each phase-modulated by subcarrier which, in turn, is modulated by data bits; switching between two carriers is alternated at high rate. Resulting composite signal is multiplied up to desired frequency and used to drive power amplifier which feeds transmitting antenna.
Easterling, M. F.↗
Real-time analysis and ground command control to achieve accurate vehicle and payload event functions.
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Duke, J. R.↗
Apollo command and service module environmental control system - Mission performance and experience.
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Hughes, D. F.↗
A roll-pitch interaction simulator and a control position command encoder for remote piloting of spin-entry research models
The Langley Research Center uses radio-controlled, scaled aircraft models to study the spin-entry characteristics of aircraft. Recent spin-entry studies required the use of an electronic proportional-control system for manipulating model control surfaces. In order to meet control system requirements, a special-purpose analog computer was designed to simulate the coupling between roll and pitch controls. A digital encoder was designed to encode the voltage analogs of control-surface position into a special pulse format for transmission to the model. This paper describes the two special developments and their relationship to the functions of the overall control system.
Meissner, C. W., Jr.↗
Apollo experience report: Command and service module communications subsystem
The development of spacecraft communications hardware from design to operation is described. Programs, requirements, specifications, and design approaches for a variety of functions (such as voice, telemetry, television, and antennas) are reviewed. Equipment environmental problems such as vibration, extreme temperature variation, and zero gravity are discussed. A review of the development of managerial techniques used in refining the roles of prime and subcontractors is included. The hardware test program is described in detail as it progressed from breadboard design to manned flight system evaluations. Finally, a series of actions is recommended to managers of similar projects to facilitate administration.
Lattier, E. E., Jr.↗
Balloon-borne ultraviolet stellar spectrometer: Acquisition, tracking and command systems
The NASA Balloon-borne Ultraviolet Stellar Spectrometer (BUSS) which is carried to an altitude of 40 km by a 15 million cubic foot balloon for night-time observations of ultraviolet stellar spectra is discussed. The BUSS optical system, comprising an 0.40 m aperture Cassegrain telescope and an Ebert-Fastie spectrometer, points at various selected stars and focuses a portion of their spectra on the photocathode of an image dissector tube. The spectral region between 2,775 Angstroms and 2,825 Angstroms is sampled by the detector at 0.25 Angstroms increments using photon counting techniques. The pointing system for the payload uses a pair of orthogonal magnetometers which sense the earth's magnetic field for an aximuth reference, and a platform potentiometer for an elevation reference. This pointing system places the target star within the 3x1 degree field of view of an outer optical star tracker. The outer star tracker is then used to point the entire instrument to within one arc minute of the target star.
Gibson, W. C.↗
Performance of a UTC FW-4S solid propellant rocket motor under the command effects of simulated altitude and rotational spin
One United Technology Center FW-4S solid-propellant rocket motor was fired at an average simulated altitude of 103,000 ft while spinning about its axial centerline at 180 rpm. The objectives of the test program were to determine motor altitude ballistic performance including the measurement of the nonaxial thrust vector and to demonstrate structural integrity of the motor case and nozzle. These objectives are presented and discussed.
Merryman, H. L.↗
COMMAND: A FORTRAN program for simplified composite analysis and design
A FORTRAN program is presented for preliminary analysis and design of multilayered composite panels subjected to inplane loads. All plys are of the same material. The composite is assumed symmetric about the midplane, but need not be balanced. Failure criterion includes limit ply strains and lower bounds on composite inplane stiffnesses. Multiple load conditions are considered. The required input data is defined and examples are provided to aid the use in making the program operational. Average panel design times are two seconds on an IBM 360/67 computer. Results are compared with published literature. A complete FORTRAN listing of program COMAND is provided. In addition, the optimization program CONMIN is required for design.
Vanderplaats, G. N.↗
Command decoder system
The production and testing of hardware design for use in evaluating shuttle instrumentation, data processing, and ground checkout operations are described. Changes incorporated to make improvements as a result of system testing are included.
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Mark 3-77 DSN command system
A comparison is made with the Mark III-75 System Configuration to explain the implementation required to establish the Mark III-77 System Configuration.
Stinnett, W. G.↗
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.↗
Control logic to track the outputs of a command generator or randomly forced target
A procedure is presented for synthesizing time-invariant control logic to cause the outputs of a linear plant to track the outputs of an unforced (or randomly forced) linear dynamic system. The control logic uses feed-forward of the reference system state variables and feedback of the plant state variables. The feed-forward gains are obtained from the solution of a linear algebraic matrix equation of the Liapunov type. The feedback gains are the usual regulator gains, determined to stabilize (or augment the stability of) the plant, possibly including integral control. The method is applied here to the design of control logic for a second-order servomechanism to follow a linearly increasing (ramp) signal, an unstable third-order system with two controls to track two separate ramp signals, and a sixth-order system with two controls to track a constant signal and an exponentially decreasing signal (aircraft landing-flare or glide-slope-capture with constant velocity).
Trankle, T. L.↗
Design development of the Apollo command and service module thrust vector attitude control systems
Development of the Apollo thrust vector control digital autopilot (TVC DAP) was summarized. This is the control system that provided pitch and yaw attitude control during velocity change maneuvers using the main rocket engine on the Apollo service module. A list of ten primary functional requirements for this control system are presented, each being subordinate to a more general requirement appearing earlier on the list. Development process functions were then identified and the essential information flow paths were explored. This provided some visibility into the particular NASA/contractor interface, as well as relationships between the many individual activities.
William H. Peters↗
Combined monitoring, decision and control model for the human operator in a command and control desk
A report is given on the ongoing efforts to mode the human operator in the context of the task during the enroute/return phases in the ground based control of multiple flights of remotely piloted vehicles (RPV). The approach employed here uses models that have their analytical bases in control theory and in statistical estimation and decision theory. In particular, it draws heavily on the modes and the concepts of the optimal control model (OCM) of the human operator. The OCM is being extended into a combined monitoring, decision, and control model (DEMON) of the human operator by infusing decision theoretic notions that make it suitable for application to problems in which human control actions are infrequent and in which monitoring and decision-making are the operator's main activities. Some results obtained with a specialized version of DEMON for the RPV control problem are included.
Muralidharan, R.↗
Apollo command module lunar excursion module docking and crew transfer study
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Left seat command or leadership flight, leadership training and research at North Central Airlines
The need for flight leadership training for flight deck crewmembers is addressed. A management grid is also described which provides a quantitative management language against which any number of management behaviors can be measured.
Foster, G. C.↗