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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Decoding tree consisting of 40-bit semiconductor read-only memories interconverts binary and decimal numbers 50 to 100 times faster than current methods. Decimal-to-binary conversion algorithm is based on a divided-by-2 iterative equation, binary-to-decimal conversion algorithm utilizes multiplied-by-2 iterative equation.
Convolutional coding, used to upgrade digital data transmission under adverse signal conditions, has been improved by a method which ensures data transitions, permitting bit synchronizer operation at lower signal levels. Method also increases decoding ability by removing ambiguous condition.
Upper and lower bounds of probability of error derived for optimum decoders using convolutional codes
Sequential decoding algorithms and flow charts for convolutional coding techniques
Bit error probability after decoding for binary perfect single error correcting codes
Digital simulation of linear filter, investigating noise and rounding errors effects on decoding signals from lunar and interplanetary probes
Digital PCM telemetry link coding techniques, discussing encoding-decoding complexity, and concatenated block scheme for channel
Transmission of parity bits together with data bits by a rate one half convolutional code of 25-bit constraint length, with sequential decoding of received signal increases quantity and accuracy of data transmitted by pulse code modulated system operating at given power level.
Convolutional coding techniques including constructing inverses, algorithms, and code comparing for sequential decoding
Description of error correcting methods for use with digital data computers and apparatus for encoding and decoding digital data
Viterbi algorithm for decoding convolutional codes for space channel application
Performance tests of convolutional decoder systems for high data rate telemetry links
Comparison of concatenated and sequential decoding systems and convolutional code structural properties
Error correction coding/decoding techniques integration, discussing convolutional and block coding and Viterbi, Sequential and Threshold decoding algorithms
Design of feedback shift register with three tap feedback decoding scheme is described. Application for obtaining sequence synchronization patterns is examined. Operation of the circuitry is described and drawings of the systems are included.
Thick film hybrid techniques are used to develop circuitry for a brushless dc motor commutator. The power commutator contains the driving circuit and an amplifier that controls the armature current. A position decoder contains digital integrated circuits which receive the signals from the armature position sensors and generate the driving signals for the power commutator in the proper sequence. These units drive motors with stall currents up to about 400 mA.
A baseline design is presented of a digital communications link between an advanced manned spacecraft (AMS) and an earth terminal via an Intelsat 4 type communications satellite used as a geosynchronous orbiting relay station. The fabrication, integration, and testing of terminal elements at each end of the link are discussed. In the baseline link design, the information carrying capacity of the link was estimated for both the forward direction (earth terminal to AMS) and the return direction, based upon orbital geometry, relay satellite characteristics, terminal characteristics, and the improvement that can be achieved by the use of convolutional coding/Viterbi decoding techniques.