Showing papers on "Time-division multiplexing published in 1975"

A dynamic packet-switching system for satellite broadcast channels

Abstract: A new satellite multi-access scheme for packet-switching computer communications combines a dynamic allocation technique with conventional time-division multiplexing to minimize delays and maximize traffic thruput. The scheme is designed to give the shortest delays to short-duration interactive or priority traffic, at the expense of longer delays for large data transfers. Simulation results show markedly improved delay-thruput characteristics over conventional time-division multiplexing for a wide range of traffic mixes, with especially significant performance gains as the traffic imbalance among the nodes increases.

A Digital Block-Processor for SSB-FDM Modulation and Demodulation

Abstract: A new algorithm is proposed for the digital implementation of the M -channel SSB-frequency-division multiplexing (FDM) modulator and demodulator, which is computationally attractive and inherently insensitive to parameter quantization.

Device for multiplexing N plesiochronous digital trains

Abstract: The invention comes within the field of multiplex digital transmissions. It concerns a device for multiplexing n digital plesiochronous trains into a more rapid digital train, comprising n channel elements for synchronizing together the plesiochronous trains by adding of extra bits called "justification bits" and a multiplexing element for sending out, from the synchronized trains, the rapid multiplex train. According to the invention, each of the channel elements comprises means for inserting, at a determined location place in the corresponding synchronized train, a justification request signal, the said multiplexing element comprising means for reading each of the n justification request signals and controlling the insertion in the multiplex train of justification indicator bits and means for giving, if required, to the corresponding channel element, the permission to effect a justification.

Note selector circuit for electronic musical instrument

Abstract: An electric organ utilizes digital encoding and time division multiplexing to transfer both function selection and note selection information from manually operable switches to respective memories, and to simultaneously produce tone signals corresponding to stored note selection information. A single encoding circuit encodes in binary form the function and note selection information during successive scanning periods established by a single multiplexing circuit. A plurality of stored note codes are transferred on a time division multiplexing basis to a note selector which selectively produces all of the selected tone signals, on one output in multiplexed form. The tone signals are demultiplexed to generate a corresponding plurality of tone signal outputs. An octave selection circuit which is responsive to a part of each note code selectively reduces the frequency of the demultiplexed tone signals. In response to storage of the code for a memory function, the note code memory operates to maintain note codes in storage after deactuation of the switches corresponding thereto until it is updated with new note codes in response to selection of a new set of notes.

Tone selector circuit with multiplexed tone data transfer

Abstract: An electric organ utilizes digital encoding and time division multiplexing to both transfer function selection and note selection information from manually operable switches to respective memories, and to simultaneously produce a plurality of tone signals corresponding to stored note selection information. A single encoding circuit during successive scanning periods established by a single multiplexing circuit encodes in binary form the function and note selection information. A plurality of stored note codes are transferred on a time division multiplexing basis to a note selector which selectively produces in multiplexed form on one output all of the tone signals. These tone signals are demultiplexed to generate a corresponding plurality of tone signal outputs. An octave selection circuit responsive to a part of each note code selectively reduces the frequency of the demultiplexed tone signals. In response to storage of the code for a memory function, the note code memory operates to maintain note codes in storage after deactuation of the switches corresponding thereto until automatically updated with new note codes in response to selection of a new set of notes.

Telecommunication switching system - uses TDM to connect entry ports to exit ports. uses matrix of switches and memory with record of source and destination ports

Abstract: The telecommunications switching system connects a number of input lines to a number of output lines using a time division multiplexing arrangement. Each time-division multiplexed line entering the switching system is synchronised and connected to the entry ports of the switching system. There is a matrix of switches which is regulated by a control circuit, and this control circuit has a memory containing the source and destination ports, and the time slice, corresponding to each channel. This controller ensures that the appropriate switches are activated at the correct time so that each entry port is connected to the correct exit port.

Methods for Supplying Interactive Services on Broad-Band Communication Networks

Abstract: The features and limitations of time- and frequencydivision miltiplexed (TDM and FDM) systems for providing interactive services on broad-band communication networks are considered. We find that TDM systems make efficient use of bandwidth for digital signal rates below 10 kbits/s while FDM systems are efficient for analog signals and digital signal rates above 1 kbit/s. Although TDM and FDM systems can employ static allocation in which fixed channels are assigned to subscribers, dynamic allocation increases the efficiency of bandwidth usage by an order of magnitude. A TDM interrupt scheme appears to be the most efficient way to identify requests and process control signals in a dynamic allocation system, but introduces a problem of interference between simultaneous signals (not present with a polling technique for request identification).

Level-code encoded multiplexer

Abstract: Apparatus for multiplexing a large number of digital signals onto a few aog channels using a level code encoded multiplexer. Each digital signal to be multiplexed is assigned a unique reference level to represent a logical "one", with all digital inputs assigned the same zero ground as a base line for a logical "zero".

A Preliminary Design of a TDMA System for FLEETSAT

Abstract: : A time division multiplexing scheme is described for use with FLEETSAT. Available communications circuits would be shared among a much larger pool of users by demand assignment, with a central controller allocating satellite resources. The system achieves rapid circuit assignments and preemptions with relatively high efficiency.

System Design Methodology For Guided Optical Communication Links

Abstract: Guided Optical Cable System design methodology is developed by considering the application criteria and the interactive process of performing system-level conceptual design trades. The design impact of user performance requirements and other user considerations are identified, and practical examples of user evaluation criteria are presented. The cyclic process of interacting component hardware capabilities with system-level design implementations is presented by defining the interaction of spatial and electronic multi-plexing, frequency-division multiplexing and time-division multiplexing, and baseband analog and digital modulation base trades. Optical link budgets for these implementation concepts are presented to show the effects of source power, source line width, optical cable losses and dispersions, and receiver sensitivities. The paper is concluded with an example that shows the use of guided optical communications systems is best optimized when inherent characteristics are exploited by the conceptual designer.© (1975) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.