Development of an acoustic modem using synthesizable microcontroller

In this thesis, an acoustic modem is developed on a digital programmable device for underwater communications. The system consists of a synthesize microcontroller as well the different elements necessaries for the modulation and demodulation of the signals. That should be developed for the design. The objective is to develop the system using a high-level hardware description language and to show the system’s functioning on a flexible platform (a programable logical device) with the perspective that, in the future, it can be implemented in a personalized integrated circuit and thus obtain a compact and energy efficient system

PC-Based Data Acquisition using PCL-208

DAQ (Data AcQuisition) is simply the process of bringing a real-world signal, such as avoltage, into the computer, for processing, analysis, storage or other data manipulation. A Physical phenomena represents the real-world signal you are trying to measure. In order to optimize the characteristics of a system in terms of performance, handling capacity and cost, the relevant subsystem can be combined together. Analog data is generally acquired and transformed into the digital form for the purpose of processing, transmission and display. Rapid advances in Personal Computer (PC) hardware and software technologies have resulted in easy and efficient adoption of PCs in various precise measurement and complex control applications. A PC based measurement or control application requires conversion of real world analog signal into digital format and transfer of digitized data into the PC. A data acquisition system that performs conversion of analog signal to digital data and the digital data to analog signal is interfaced to a pc to implement the functions of a measurement and control instrumentation applications. In this project we have used the electromagnetic sensor to acquire the data of a magnetic disk angular velocity, which we have got in mili volts range. This has been further transformed approximately into the range of 5 volt by using an operational amplifier of suitable gain (~30)and then rectified .We then transformed the analog voltage into digital by using ADC 0804 and the processing part is done by using ATMEL89c51.In the second phase we have used the data acquisition card PCL-208 and 207 to interface the amplified output to PC by the help TURBO C (C compiler)

A versatile data acquisition system for capturing electromagnetic emissions in VHF band

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This research investigates the occurrence of EM emissions from compressed rock and assesses their value as precursors to earthquakes. It is understood that electromagnetic emissions are accompanied by crack generation in the Earth's crust, and effort has been targeted on the analysis of electromagnetic signals preceding seismic events. There is a need for a robust Data Acquisition System for the reliable collection of such signals. The design and deployment of a novel system form part of this research. The EM data collected by the Data Acquisition System is subsequently analysed and correlations are made with natural phenomena. The design of the Data Acquisition System is presented and meets a specification which includes accuracy, robustness, power consumption, remote configurability achieved by the development of a novel architecture for flash memories which significantly increases the live span of these devices. The measuring of electromagnetic emissions should be performed by reliable systems, using devices that fully correspond to the specifications set by the needs of this research. This type of systems is not fully covered by existing commercial devices. These prototype VHF field stations (ground base - electromagnetic variation monitors in VHF band) are located around the Hellenic Are. This region is one of the most seismically active regions in western Eurasia due to subduction of the oceanic African lithosphere beneath the Eurasian plate. After approximately two years of electromagnetic VHF data collection, the final stage of this project took place. In this stage, possible correlation between naturally occurring electromagnetic emissions in VHF band and seismic events within a predefined radius around the observation location is investigated. Supplementary, effects of alternative electromagnetic sources, such as solar activity, is considered. Whilst EM emissions from compressed rocks can be demonstrated in the laboratory, it was found from a two-year evaluation that no reliable correlation with earthquake events could be established. However, significant patterns of activity were detected in EM spectrum and it was shown that these correlate strongly with other naturally occurring phenomena such as solar flares. The Data Acquisition System as developed in this thesis has related applications in long term and remote sensing operations including meteorology, environmental analysis and surveillance.Funding was obtained from the National Foundation of Scholarships (I. K. Y.), and co-funded by the European Social Fund and National Resources - (EPEAEK II) ARXIMIDIS