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Institution

Codex Corporation

About: Codex Corporation is a based out in . It is known for research contribution in the topics: Network packet & Signal. The organization has 189 authors who have published 241 publications receiving 32205 citations.


Papers
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PatentDOI
Mei Yong1
TL;DR: In this article, a spectral interpolation (500, 600) and efficient excitation codebook search method (700) were developed for a Code-Excited Linear Predictive (CELP) speech coder.
Abstract: A novel spectral interpolation (500, 600) and efficient excitation codebook search method (700) developed for a Code-Excited Linear Predictive (CELP) speech coder (100) is set forth. The interpolation is performed on an impulse response of the spectral synthesis filter. As the result of using this new set of interpolation parameters, the computations associated with an excitation codebook search in a CELP coder are considerably reduced. Furthermore, a coder utilizing this new interpolation approach provides noticeable improvement in speech quality coded at low bit-rates.

61 citations

Journal ArticleDOI
TL;DR: The authors find that for the range of network parameters of practical interest, an end-to-end approach towards error control is superior to a link-by-link approach, even under assumptions that would overly favor the link- by- link approach.
Abstract: The authors examine the performance of two different approaches for handling the loss and/or corruption of messages as they are transmitted between two end users in a high-speed network. In the link-by-link approach, two adjacent nodes in an end-to-end path locally detect and recover from message loss or corruption along their joining link. In the end-to-end approach, recovery is done solely on the basis of a single end-to-end protocol. The authors develop analytic performance models, validated with simulation, for comparing the performance of these two approaches. The authors find that for the range of network parameters of practical interest, an end-to-end approach towards error control is superior to a link-by-link approach, even under assumptions that would overly favor the link-by-link approach, while at the same time requiring fewer network resources (e.g. buffers, computation time) than the link-by-link approach. The performance differences arise primarily from the increased buffer requirements of the link-by-link approach. >

61 citations

Journal ArticleDOI
TL;DR: Simulation results show that the RLS-implemented DFE systems with coded modulation can successfully combat severe channel distortion while maintaining the coding gain over corresponding uncoded systems.
Abstract: An extension is presented of the work of V.M. Eyubogin (see ibid., vol.36, p.401-9, Apr. 1988) on decision-feedback equalization (DFE) applied to coded systems with interleaving. The authors study the adaptive implementation of the DFE using recursive-least-squares algorithms (RLS). System performance on time-dispersive channels with nulls as well as on channels with relatively small intersymbol interference is investigated. A reference insertion method is used to improve system performance, and a two-stage processing technique is adopted to use the more reliable decisions from the decoder in equalizer coefficient adaptation. Simulation results show that the RLS-implemented DFE systems with coded modulation can successfully combat severe channel distortion while maintaining the coding gain over corresponding uncoded systems. >

60 citations

Patent
23 Jul 1975
TL;DR: In this paper, an early segment of each burst of signals is used to adapt the equalizer in a decision-directed mode, and when the adaptation is completed the system switches to its normal higher rate of data transmission.
Abstract: Initial Adjustment of a receiver having an automatic adaptive equalizer in a modem communication system is accomplished by employing a data transmission rate lower than normal for an early segment of each burst of signals. At this lower rate, accurate reception is possible without complete adaptation of the equalizer. These same (early segment) signals are used to adapt the equalizer in a decision-directed mode. When the adaptation is completed the system switches to its normal higher rate of data transmission.

59 citations

Patent
06 Jan 1992
TL;DR: In this article, an approach for interfacing a network manager to a network of communication devices over a single communications channel of a plurality of signals is disclosed. But it is not described in detail.
Abstract: Apparatus for interfacing a network manager to a network of communication devices over a single communications channel of a plurality of signals is disclosed. Each communication device of the network is uniquely assigned a poll address for communication selection by the network manager which is operative to establish communication with a communication device of the network by transmitting the poll address thereof over the single communication channel. The network of communication devices are coupleable together in a daisy chain through input and output port circuits thereof to form the single communications channel. The input port circuit of each communications device receives and transmits signals from and to the single communications channel upstream of its position in the daisy chain and the output port circuit of each receives and transmits signals from and to the single communications channel downstream of its position in the daisy chain. In addition, the input port circuit of the communication device in the first position of the daisy chain is coupleable to the network manager for receiving signals, including the poll address, therefrom and for transmitting signals thereto. Each communication device further includes a control circuit which is coupleable to both the input and output port circuits thereof for governing the receiving and transmitting operations of each based on the poll address transmitted over the single communications channel by the network manager.

59 citations


Authors

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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20211
20133
20111
19991
19951
199412