Codex Corporation

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

Circuit and method of detecting an invalid clock signal

Abstract: A phase lock loop monitors the frequency of redundant input clock signals and switches back and forth therebetween should one or the other become invalid. Thus, the PLL may continue normal operation even with a failure of one input clock signal. If both the input clock signals fail, an internal reference signal maintains the PLL at a nominal operating frequency until one of the input clock signals is restored whereby the loop can quickly re-establish phase lock. To determined validity, the input clock signals are sampled and stored by the reference signal in a predetermined manner. The input clock signal is valid if the samples of the input clock signal each have the same logic state after the sampling period; otherwise, the input clock signal is invalid if the samples of the input clock signal have at least one different logic state after the sampling period.

Multiplexing of bytes of non-uniform length with end of time slot indicator

Abstract: A data transmission system is described wherein data in a plurality of constituent streams are received at a multiplexer, processed to form a single composite stream comprising time slots each carrying data from one constituent stream, transmitted in the composite stream over a communication link, and demultiplexed in a demultiplexer receiving the composite stream at the far end of the link to recover the original plurality of constituent streams in separate form. The system implements a protocol according to which a plurality of queues, each associated with one of the constituent streams and arranged and connected to receive and store data therefrom, are serviced by a sequence of time slots corresponding to a defined service sequence, the data in any one slot being derived from an associated queue, and being formed into codewords from a codeword set, with framing apparatus emitting terminator codewords to mark the ends of at least some slots.

Compact expandable folded first-in-first-out queue

Abstract: An expandable FIFO circuit is provided for storing data words in a plurality of data cells (17, 18, 19, 20, 21, 23, 24, 26, 27, 29, 30) in response to a digital position control signal generated by a plurality of control cells (16, 19, 22, 25, 28) such that the oldest data word is always present at the output data bus. The data cells are arranged in pairs for data transferring therebetween whereby the data words are placed in the upper and lower data cells of each pair before allocating data cells farther from the input data bus. The digital position control signal is represented as a first portion having a first logic state and a second portion having a second logic state, the boundary of which determines the occupied portion of the data cells which provides control of the movement of data words therein. The FIFO circuit is expandable without modification of the preexisting data cells or control cells simply by adding data cell pairs and associated control cells.

Integrating life-cycle cost and cost-of-ownership in the commercial sector

Abstract: The author describes two models, the LCC (life cycle cost) model and the COO (cost of ownership) model, and their use as an aid in meeting the objective of creating products that have the lowest LCC for both the manufacturer and the customer. First, the what and why of the LCC analysis process are discussed, and the objectives are defined. The model is described in terms of the major cost elements, as well as the various model variables. The use of the results as a planning tool in the decision-making process is emphasized. Sample baseline runs are provided to demonstrate the implementation and utility of the model, and illustrate the reporting formats. Then, the COO model is presented to provide the customer perspective of LCC. The utility of the model in helping to leverage product sales and services is explained. An overview of the COO model is also furnished in terms of mechanization, input data, and application. Sample runs and tradeoffs are made to illustrate the relative COO for varying levels of service maintenance contract options. >

Trellis shaping

Abstract: The author discusses trellis shaping, a method of selecting a minimum-weight sequence from an equivalence class of possible transmitted sequences by a search through the trellis diagram of a shaping convolutional code C/sub s/. Shaping gains on the order of 1 dB may be obtained with simple four-state shaping codes and with moderate constellation expansion. The shaping gains obtained with more complicated codes approach the ultimate shaping gain of 1.53 dB. With a feedback-free syndrome-former for C/sub s/, transmitted data can be recovered without catastrophic error propagation. Constellation expansion and peak-to-average energy ratio may be effectively limited by peak constraints. With lattice-theoretic constellations, the shaping operation may be characterized as a decoding of an initial sequence in a channel trellis code by a minimum-distance decoder for a shaping trellis code based on the shaping convolutional code, and the set of possible transmitted sequences is then the set of code sequences in the channel trellis code that lie in the Voronoi region of the trellis shaping code. >