Showing papers on "Frequency-division multiplexing published in 1967"

Design of Block-Coded Communication Systems

Abstract: The design and performance of frequency multiplexed, phase-modulated communication systems is presented. In particular, the transmitter is assumed to be an ideal phase modulator which modulates a RF carrier with N phase-modulated, sinusoidal data subcarriers, and in general, M binary-valued composite signals. The receiver is a superheterodyne phase-locked loop (PLL) whose output is applied to one of N subcarrier extractors. Each subcarrier extractor consists of a subcarrier tracking loop, a timing loop, and a data detector which operates as a cross-correlator. The paper presents results which allow the design engineer to allocate the total power between N modulated data subcarriers, M binary-valued signals, and the carrier signal. The total power in the distortion component is computed. Finally, a method is given which allows the communications engineer to select the data rate and the modulation factor of each data subcarrier which will minimize the probability that the data detector will err in the decision process. The results are sufficiently general so that they may be used in designing block-coded systems. Such systems have application in various branches of aerospace communication engineering, e.g., channelized communication satellites and deep-space probes.

Television time multiplexing system

Abstract: Described is apparatus for transmitting a plurality of black and white television video signals over a single cable, or on a single carrier frequency, to separate receivers. This is accomplished by means of time-sharing multiplexing techniques wherein a frequency burst on the video blanking pulse, similar to a color burst used in color television systems, is utilized at the receiving end of the system for demodulating or separating the two multiplexed video signals.

Single channel monopulse techniques

Abstract: : This report describes the results of a study and investigation to obtain a technique for processing both the communications and tracking signals in a single receiver in a satellite communications system. Various techniques were studied, with emphasis on Pseudo-Monopulse, Frequency Division Multiplexing, Time Division Multiplexing, and the Automatic Manual Simulator (AMS), a mechanical scanning method. All systems were analyzed to determine basic feasibility. Detailed analyses of the most promising techniques (Pseudo- Monopulse, AMS, FD), were made. Major factors considered were: performance in the presence of thermal noise, errors due to phase and amplitude unbalance, normalization (dependence of pointing error on received signal strength), acquisition problems, and equipment complexity. A relative evaluation of all Single Channel Monopulse Tracking Receiver (SCMTR) techniques, including three channel monopulse for comparison, was made, and Pseudo-Monopulse was shown to offer the most advantages for the stipulated conditions. A complete Pseudo- Monopulse receiver design was accomplished and is included in this report. The AMS technique was shown to be useful when equipment simplicity is the prime goal.

Engineering and Application Features of the 46B Cable Carrier System

Abstract: This paper describes a new 24-channel cable carrier system which is end-to-end compatible with the Western Electric N3. The synchronization technique is described, and the method used to provide synchronization when working end-to-end with an N3 terminal is discussed. Level stability, data transmission capability, and general considerations in the layout of the carrier frequency repeatered line are reviewed.