M.K. Oolun

Speed sensorless control of a converter-fed DC motor

This paper presents a speed sensorless control scheme for a DC motor driven by a DC-DC converter. The proposed system is based on the computation of the motor speed from the converter output line parameters. The performance of the designed system is also evaluated.

Higher order adaptive arithmetic coding using the prediction by partial match algorithm

Arithmetic coding completely bypasses the traditional coding paradigm that replaces an input symbol by a specific code. Arithmetic coding represents a stream of input symbols by a single codeword. The modelling paradigm is a key aspect in effective data compression. We present an adaptive higher order arithmetic coding scheme using the prediction by partial match (PPM) algorithm as well as a framework for the comparison of the different compression techniques. Simulation study conducted with this framework shows that compressive effectiveness and implementing complexity increases as the order increases but above a certain order there is no gain in compression with increasing costs.

Adaptive coding technique employing concatenated Reed Solomon and convolutional codes

An adaptive coding scheme employing concatenated Reed Solomon codes and convolutional codes has been proposed. This scheme employs the information available from the channel state estimator to vary the amount of redundancy and its error correcting capability according the state of the channel. Simulations have been carried in AWGN and slow Rayleigh fading channels and the results show that the adaptive concatenated scheme gives significant amount of improvement over the concatenated scheme.

ICT development in Mauritius

Although Mauritius has evolved from a low-income mono-crop economy at independence to a middle-economy income today, it still faces a number of threats mainly from low cost competitor countries. To remain competitive in the world market and to transform Mauritius into a regional hub and to make it an IT exploiter and exporter government is giving high priority to the development of the ICT sector. It aims at making ICT the fifth pillar of the Mauritian economy. In this country report the strategies being adopted to set up e-government and e-education and training and to foster the development of the Cybercity are presented.

A current-regulated field-oriented induction motor drive using a fuzzy controller

This paper presents an indirect field-oriented induction motor drive where the torque and flux producing components of the stator current are generated from a fuzzy-logic based controller. Results show that the proposed system tracks command speeds and reject step disturbances in load torque with zero steady-state errors by providing instantaneous torque control.

Four-quadrant current-regulated DC servo drive using a fuzzy logic-based controller

DC servo drives normally employ an internal current loop as well as a speed control loop requiring the use of a speed transducer. This paper presents a fuzzy logic controlled DC servo drive without the need for mechanical speed sensors. Speed estimation is performed from measurements of the input current and voltage to the motor. The latter is driven by a current-regulated voltage source DC-DC converter capable of operating in all four quadrants of the torque-speed plane. The fuzzy controller uses the calculated rotor speed to produce the armature current command necessary for matching the reference speed profile. The proposed system is shown to track the dynamic input speed settings and to reject step load disturbances with largely reduced settling times and steady state errors.

A combined coded and DSP based technique for identifying linear systems

The paper presents a coded interrogation approach to linear system identification on a TMS320C30-based platform. Computer generated Golay sequences are used for stimulating a system under test. A fast DSP-based system has been designed for the response acquisition, and processing. Results of tests carried out on linear circuits are reported.

Hybrid BFSK/MPSK modulation employing GAC codes

In this paper a hybrid binary frequency shift keying/multiple phase shift keying (BFSK/MPSK) modulation technique employing generalised array codes (GAC) and trellis decoding is proposed. The performances of the GAC employing the hybrid BFSK/MPSK are compared with those employing BPSK, MPSK schemes and the corresponding uncoded MPSK scheme.

Internet-based data acquisition system via a PSTN

This paper presents the design and implementation of a web-based data acquisition system from remote station sites. It allows regular updates of telemetry data to be made at pre-defined intervals, for a multiuser environment. The proposed system is constructed around a host PC connected to the PSTN via an internal modem at one end, and a number of remote terminal units (RTU), each located at one of the sites. The host PC is part of a LAN, and is connected to a server. Data acquired from the sites by the host PC, are finally transferred to the server, which is configured as an Internet Information Server (IIS). A web site is hosted on that server to allow user-access to the data. The system can be operated in both on-line and off-line modes.

Active noise control in real-time using a TMS320C50 DSP system board

This paper presents a real-time active noise controller system, based around a TMS320C50 DSP system board. The proposed technique consists of identifying the noisy space medium where the cancellation needs to be effected using a coded interrogation technique, and subsequently cancelling the noise using a simple, yet robust prediction strategy. Software coding and implementation has been achieved, with a signal-to-noise ratio improvement of up to 16 dB. The time taken to achieve this performance is about 32 s, for a wideband noise over the range 50 to 200 Hz. Once the system has learned the noise characteristics of the medium, it offers good tracking characteristics in cancelling the noise thereafter.