The process of transfer a speech signal by high confidentially and as quickly as possible through the Internet needs to develop compression and encryption technology for a speech signal, so as, to reduce its size and make it understandable to persons
not authorized to listen to.
A system was designed to encrypt the voice over Internet Protocol (VoIP) and use compression technique for the purpose of reducing the size of data and send it over the network, (A_law PCM) algorithm was used the to compress audio data. Then algorithms of Triple Data Encryption Standard (TDES) and Advanced.
Encryption Standard (AES) were applied. A new encryption algorithm was proposed based in its work on the block cipher encryption system called the Direct and Reverse algorithm, which based on three basic steps, firstly expand the initial key, secondly direct the encryption of each round in one direction, and finally substitute (Bytes) as used in the Compensation Box in AES algorithm by making it moving. In general compression ratio was calculated and it was (50%) and the results of the correlation coefficient for the proposed algorithm was compared with the results of (AES, TDES) algorithms.
The presented paper deals with an implemented speed sensorless direct vector control (DVC) technique based on stator flux orientation algorithm to estimate and control rotor speed of three phase induction motor (IM). The driver system is presented in
this paper has a three phase bridge uncontrolled rectifier and space vector pulse width modulated (SV-PWM) inverter to drive and control the speed of the (IM) at different mechanical load conditions. The rotor speed has been obtained by slip frequency estimation instead of use feedback speed sensor. The structure of Volt/Freq via PI-controller is used to control and adjust speed accuracy between required and estimation rotor speed to precise speed response. The proportional and time integration controller values obtain by Ziegler-Nichols closed-loop tuning method. Computer simulation results with Matlab/Simulink program show an acceptable speed control response, minimum error at steady state and dynamic condition, a results show also the stator voltage, current and flux estimated in direct-quadrate of stationary and synchronous reference frame at variation in load up to (10 N.m) beside the synchronous, slip and rotor speed estimation are varied between (250-1486 rpm).
Keywords: Induction Motor Drive System, Direct Vector Control, Speed Sensorless.
