International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / IRIG-106 Chapter 5 describes a method for encoding voice using a simple circuit to reduce the overall bit rate and still achieve good quality voice. This well described Continuously Variable Slope Delta Modulation (CVSD) circuit can be obtained using analog parts. A more stable implementation of CVSD can be obtained by designing an anti-aliasing input filter, an A/D converter, and logic. This paper describes one implementation of the CVSD using a standard A/D converter and logic.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / This paper describes the design and characteristics of a digital voice encoding circuit that uses the continuously variable slope delta (CVSD) modulation/demodulation method. With digital voice encoding, the audio signal can be placed into the pulse code modulation (PCM) data stream. Some methods of digitizing voice can require a large amount of bandwidth. Using the CVSD method, an acceptable quality of audio signal is obtained with a minimum of bandwidth. Presently, there is a CVSD microchip commercially available; however, this paper will describe the design of a circuit based on individual components that apply the CVSD method. With the advances in data acquisition technology, increased bit rates, and introduction of a corresponding MIL-STD, CVSD modulated voice will become more utilized in the flight test programs and a good knowledge of CVSD will become increasingly important. This paper will present CVSD theory, supported by graphical investigations of a working circuit under different conditions. Finally, several subjects for further study into CVSD will be addressed.

Les systèmes méandriformes construisent, à long terme, des architectures sédimentaires composées de corps poreux disséminés dans un volume de sédiments peu perméables. Ces corps sont susceptibles de contenir des ressources naturelles. Afin d'optimiser leur exploitation, il importe d'estimer la répartition et la connectivité de ces corps. À cet effet, Mines-Paristech développe Flumy, un logiciel de modélisation par processus de ces architectures . Cette thèse vise à améliorer la simulation de la migration dans Flumy en introduisant une influence.Pour cela, trois différents modèles ont été reliés entre eux et comparés. Le premier (modèle à pente constante) est celui actuellement en place dans Flumy, héritier des travaux de [Ikeda 1981] et dans lequel la pente de la surface du cours d'eau est constante. Le deuxième (modèle à pente variable) fut proposé par [Lopez 2003]. Il attribue à la surface libre la pente locale de la topographie. Enfin, un dernier modèle (modèle Saint Venant) a été élaboré en modifiant le précédent. L'écoulement moyen, initialement calculé sous une surface libre connue, est désormais obtenu par résolution des équations de Saint Venant sur un fond connu. Ces trois modèles ont été appliqués à la migration à long terme de méandres libres. Les modèles à pente constante et à pente variable ont également été utilisés pour reproduire les méandres confinés de deux rivières canadiennes, la Beaver et la Red Deer.Les résultats montrent un développement plus réaliste des méandres simulés avec le modèle à pente variable que de ceux simulés avec le modèle à pente constante. Cette amélioration est observable dans les méandres isolés (ralentissement de la vitesse d'extension) et dans les trains de méandres (confinement en ceintures de méandres). Le modèle à pente variable permet également une meilleure reproduction de la morphologie des méandres confinés. L'utilisation du modèle Saint Venant apporte les mêmes améliorations dans la simulation des méandres libres, quoique moins prononcées. Il permet surtout de construire une surface libre physique sur une grande variété de fonds, résolvant ainsi une limite identifiée dans le modèle à pente variable. / Over a long time, Meandering systems build sedimentary architectures composed of porous bodies scattered inside a volume of low-permeability sediments. These bodies may contain natural resources. In order to optimize their mining, it is essential to estimate the distribution and connectivity of such bodies. To this end, Mines ParisTech develops Flumy, a process-based model simulating the formation of these architectures. This thesis aims to improve the simulation of the migration in Flumy by taking into consideration the influence of the local slope.For this purpose, three distinct models were considered in conjunction, and compared. The first one (constant slope model), which constitutes the basis of the current Flumy version, was originally developed by [Ikeda 1981]. The second model (variable slope model), developed by [Lopez 2003], assigns to the free surface the slope of the surrounding topography. Finally, the last model (Saint-Venant model) has been derived from the variable slope model. Initially calculated under a known free surface, the mean flow in each cross-section is now obtained by solving the Saint-Venant equations over a known river bed. Each of those three models has been applied to the simulation of free meanders. Moreover, the constant-slope and variable slope models have been used to reproduce the confined meanders of two Canadian streams.The results point to a more realistic meanders development using the variable slope model than with the constant slope model. This improvement can particularly be observed in individual meanders, whose rate of extension decreases with the age. It is also noticeable in the overall river behavior, which self-confines in a meander belt. The specific morphology of the confined meanders is also better reproduced using the variable slope model than with the constant slope model. Lastly, though a lesser extent, the Saint-Venant model shows the same advantages than the variable slope model. In addition, it allows the construction of a physically meaningful free surface over a wide range of beds and, in doing so, resolves a limit of the variable slope model.

Due to the inherently hierarchical nature of many natural phenomena, data collected rests in nested entities. As an example, students are nested in schools, school are nested in districts, districts are nested in counties, and counties are nested within states. Multilevel models provide a statistical framework for investigating and drawing conclusions regarding the influence of factors at differing hierarchical levels of analysis. The work in this paper serves as an introduction to multilevel models and their comparison to Ordinary Least Squares (OLS) regression. We overview three basic model structures: variable intercept model, variable slope model, and hierarchical linear model and illustrate each model with an example of student data. Then, we contrast the three multilevel models with the OLS model and present a method for producing confidence intervals for the regression coefficients. / text

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Today’s telemetry systems can reduce spectrum demand and maintain secure voice by encoding analog voice into digital data using; Continuously Variable Slope Delta Modulation ( CVSD ) format and imbedding it into a telemetry stream. The model CSC-0390 DvD system is an excellent choice in decoding digital voice, designed with flexibility, efficiency, and simplicity in mind. Flexibility in design brings forth a capability of operating on a wide variety of telemetry systems and data formats without any specialized interfaces. The utilization of 74HC series circuit technology makes this DvD system efficient in design, low cost, and lower power consumption. In addition the front panel display and control function is also is an example of Simplicity in design and operation.