One frame delta encoder final report
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Hackett, K. R.↗
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Improved digital TV encoding and decoding system
Analog-to-digital coder and digital-to-analog decoder system handles wideband TV signals. The system incorporates solid state plug-in modular units and is operated in a VSD /Variable Slope Delta Modulation/ mode or in the conventional one-bit DM /Delta Modulation/ mode.
Deutermann, A. R.↗
Television bandwidth reduction by encoding spatial frequencies.
Fourier coding method for coding images for digital transmission, achieving bandwidth reduction for televised images
Andrews, H. C.↗
Cosmic ray experiments source-encoding in the IMP-I spacecraft.
Cosmic ray detectors design for medium, low and very low energy events on IMP-1 spacecraft, noting PCM format
Cancro, C. A.↗
Test and preliminary flight results on the sequential decoding of convolutional encoded data from Pioneer IX.
Pioneer 9 deep space probe with telemetry link operated in coded mode with sequential decoding, discussing ground and flight test data
Lumb, D. R.↗
Tree encoding of memoryless time-discrete sources with a fidelity criterion.
Tree codes for memoryless time discrete sources with bounded fidelity criterion
Jelinek, F.↗
Modification to the MED and LED source-encoding circuitry for the IMP H and J spacecraft
The circuitry and fabrication changes made on the MED and LED electronics cards for the IMP H and J are reported. Except for the noted changes, the circuitry and module-matrix arrangement is essentially the same as the IMP-1 electronics cards described. In addition, analysis of the IMP-1 transmitted data indicated the desirability of incorporating additional coincident-event threshold detection levels to further discriminate between received particles.
Garrahan, N. M.↗
Source encoding of images for efficient transmission
A set of recursive rules which generate unitary transforms with a fast algorithm are presented. For each rule, simple relations give the number of elementary operations required by the fast algorithm. The common Fourier, Walsh-Hadamard, Slant, and Haar transforms are expressed with these rules. The framework developed allows the introduction of generalized transforms which include all common transforms in a large class of identical computation transforms. A systematic and unified view is provided for unitary transforms which have appeared in the literature and for a number of new transforms of potential interest. Generalization to complex and multidimensional unitary transforms is considered.
Algazi, V. R.↗
Integrated source and channel encoded digital communications system design study
Studies on the digital communication system for the direct communication links from ground to space shuttle and the links involving the Tracking and Data Relay Satellite (TDRS). Three main tasks were performed:(1) Channel encoding/decoding parameter optimization for forward and reverse TDRS links,(2)integration of command encoding/decoding and channel encoding/decoding; and (3) modulation coding interface study. The general communication environment is presented to provide the necessary background for the tasks and to provide an understanding of the implications of the results of the studies.
Huth, G. K.↗
Tree encoding for symmetric sources with a distortion measure
A simple algorithm is developed for mapping the outputs of a source into a set of code sequences generated by a tree code. The algorithm is analyzed for the case of a source producing discrete independent equiprobable letters when the distortion measure satisfies a certain symmetry condition. It is shown that the algorithm is capable of achieving an average distortion as close as desired to the minimum average distortion for the code rate given by Shannon's rate-distortion theorem.
Gallager, R. G.↗
Integrated source and channel encoded digital communication system design study
This study investigated the configuration and integration of a wideband communication system with a Ku-band rendezvous radar system. The goal of the study was to provide as much commonality between the two systems as possible. The antenna design was described with the only change being the requirement for dual polarization (linear for the radar system and circular for the communication system).
Huth, G. K.↗
Integrated source and channel encoded digital communication system design study
Various aspects of space shuttle communication systems were studied. The following major areas were investigated: burst error correction for shuttle command channels; performance optimization and design considerations for Costas receivers with and without bandpass limiting; experimental techniques for measuring low level spectral components of microwave signals; and potential modulation and coding techniques for the Ku-band return link. Results are presented.
Huth, G. K.↗
Capacitive shaft-angle encoder
Economical device is less subject to wear than conventional resistive-potentiometer devices.
Hruby, R. J.↗
Integrated source and channel encoded digital communication system design study
The results of several studies Space Shuttle communication system are summarized. These tasks can be divided into the following categories: (1) phase multiplexing for two- and three-channel data transmission, (2) effects of phase noise on the performance of coherent communication links, (3) analysis of command system performance, (4) error correcting code tradeoffs, (5) signal detection and angular search procedure for the shuttle Ku-band communication system, and (6) false lock performance of Costas loop receivers.
Huth, G. K.↗
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.↗
Evaluation of NASA speech encoder
Techniques developed by NASA for spaceflight instrumentation were used in the design of a quantizer for speech-decoding. Computer simulation of the actions of the quantizer was tested with synthesized and real speech signals. Results were evaluated by a phometician. Topics discussed include the relationship between the number of quantizer levels and the required sampling rate; reconstruction of signals; digital filtering; speech recording, sampling, and storage, and processing results.
Source record↗
Integrated source and channel encoded digital communication system design study
The analysis of the forward link signal structure for the shuttle orbiter Ku-band communication system was carried out, based on the assumptions of a 3.03 Mcps PN code. It is shown that acquisition requirements for the forward link can be met at the acquisition threshold C/N0 sub 0 value of about 60 dB-Hz, which corresponds to a bit error rate (BER) of about 0.001. It is also shown that the tracking threshold for the forward link is at about 57 dB-Hz. The analysis of the bent pipe concept for the orbiter was carried out, along with the comparative analysis of the empirical data. The complexity of the analytical approach warrants further investigation to reconcile the empirical and theoretical results. Techniques for incorporating a text and graphics capability into the forward link data stream are considered and a baseline configuration is described.
Udalov, S.↗
Effect of interference on delta modulator encoded video signals
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Schilling, D. L.↗