Showing papers on "Telecommunications link published in 1966"
TL;DR: This paper is concerned with the optimal design of one-way and two-way communication systems which are of greatest interest in space applications and presents a design technique in the form of a universal set of design curves which enable the communications engineer to make a "best" choice of parameters when faced with a givenSet of design constraints.
Abstract: This paper is concerned with the optimal design of one-way and two-way communication systems which are of greatest interest in space applications. A two-way communication system is defined to be one composed of two radio links or channels, viz., an up-link channel and a down-link channel. The down-link RF carrier is derived from the carrier tracking loop located in the uplink receiver. Transmission of information which does not make use of the carrier derived in the up-link receiver is referred to as oneway communications. In particular, a design technique is presented in the form of a universal set of design curves which enable the communications engineer to make a "best" choice of parameters when faced with a given set of design constraints. This means that, given a certain desired error probability, a total transmitter power limitation, data rate, and carrier tracking loop bandwidth, the modulation index, i.e., the square root of the ratio of the power in the carrier to the total transmitted power, may be chosen so as to minimize the probability of error. As an alternate technique, and one which is not as difficult to carry out, the design may be predicted on the basis of selecting that value of modulation index which maximizes the signal-to-noise ratio at the output of the data demodulator. Design curves are given which allow one to employ this alternate criterion. Further, these results should prove useful when attempting to check experimentally a design based upon the criterion of minimum error probability.
30 citations
Patent•
01 Nov 1966
2 citations
TL;DR: In this article, a military 12-channel multiplexer is built with adaptive control to maintain a preselected signal-to-noise ratio (SNR) in the voice channels allowed to be on as the downlink carrier-to noise ratio changes.
Abstract: A multichannel satellite communication system using angle modulation can use the link with optimum efficiency only if the information rate and the angle modulation parameter values are varied as a function of the satellite link status. A military 12-channel multiplexer is being built with adaptive control to maintain a preselected signal-to-noise ratio (SNR) in the voice channels allowed to be on as the downlink carrier-to-noise ratio changes. The multiplexer uses conventional single sideband voice channel modulation, but each voice channel is switched on or off by an adaptive control unit. The FM modulator and demodulator parameters are also switched by the adaptive control unit. A sensor provides a continuous measurement of audio SNR, which is combined with operating control inputs in the adaptive control unit. The multiplexer also coordinates its adaptive state with that of the distant terminal multiplexer through an automatic data transmission terminal.
TL;DR: A channelized quasi-linear repeater concept, which employs separate hard-limiting receiving channels feeding a common solid-state linear power amplifier, eliminates the necessity for equalizing user uplink powers, minimizes crosstalk between channels, and reduces electronic counter measures (ECM) vulnerability.
Abstract: This paper describes a satellite system capable of providing world-wide communications for users having limited antenna gain, limited transmitter power, and relatively low data-volume requirements. Although emphasis is placed on the problems associated with servicing aircraft terminals, the basic system concept is compatible with other types of users having similar terminal limitations. A minimum useful system consisting of a single, 10-channel, solid-state, quasi-linear repeater operating within the 100- to 500-MHz frequency range at synchronous altitude will provide teletype links between users within the coverage of the satellite. Global coverage with vocoded and/or FM voice service, in addition to teletype (TTY), is provided by a growth version of the minimum system. The channelized quasi-linear repeater concept, which employs separate hard-limiting receiving channels feeding a common solid-state linear power amplifier, eliminates the necessity for equalizing user uplink powers, minimizes crosstalk between channels, and reduces electronic counter measures (ECM) vulnerability. Additional ECM protection can be added by frequency hopping the uplink and employing time-division multiple access, on a message basis, within the individual channels.
01 Jan 1966
TL;DR: In this paper, the authors considered the application of satellite relay techniques to provide communication paths for aircraft-ground communication over the ocean and considered the feasibility of a communication system design for air traffic control (ATC) utilizing the reflex repeater as the basic satellite-borne relay device.
Abstract: Summary This paper considers the application of satellite relay techniques to provide communication paths for aircraft-ground communication over the ocean. It considers the feasibility of a communication system design for air traffic control (ATC) utilizing the reflex repeater as the basic satellite-borne relay device. Implementation of satellite relay techniques would permit continuous line-of-sight operation for reliable ATC digital datalinks and voice transmission. The paper describes the basic use of the relay system, the repeater electronics, and the communication link parameters required to accommodate the satellite-aircraft link geometries. Examples of typical aircraft-ground link calculations are presented, and the basic supersonic aircraft communication requirements and satellite contact profiles are discussed.