M.Sc.

Abstract : The impressive development of computer networks has reached the point where security becomes essential importance for every user and organization that want to exchange data in a secured way. Today, one of the latest secure communication methods for organizations that are motivated to reduce costs and increase services is the Virtual Private Network (VPN). The VPN mechanism is based on two newest technologies, IPSec and IKE where, IPSec is a suite of protocols used to protect information and IKE is a protocol to exchanged data.

Abstract : The different available techniques for MOSFET-C integrated filters implementation are investigated in this thesis. These techniques are reviewed and compared from different points of view and the most promising approach is identified. Some well-known second-order bandpass filter circuits are converted from active-RC form to MOSFET-C form using Balanced-Amplifier Technique. Their linear performances are evaluated analytically and computer-simulated using the simulation program PSPICE and ORCAD.

Abstract : This work deals with developing suitable attitude control algorithm for a small low Earth orbit satellite of minimum cost and complexity. The proposed attitude control system deals with a combination of passive and active control methods. Passive control is represented by boom deployment to ensure Earth pointing with accuracy (of _ 50 ). Active control method is accomplished by the use of a set of mutually perpendicular coils called magnetorquer mounted on the principal axes of the spacecraft.