Subhra J. Sarkar

Modified DCSK communication scheme for PLCC based DAS with improved performance

Differential Code Shift Keying (DCSK) scheme developed in MATLAB environment require longer execution time at decoding end particularly with longer strings. The problem can be avoided by using suitable data compression technique. In this paper, Huffman Coding based data compression technique is implemented for improving the performance of DCSK Communication scheme developed for integer strings which can be extended for any character string with slight modification.

An alternative voltage and frequency monitoring scheme for SCADA based communication in power system using data compression

Conventionally in SCADA based system used in power system, voltage & frequency is monitored sequentially at regular intervals by employing suitable communication schemes. By suitable data compression techniques, it is possible to compress the measured voltage & frequency data to a reduced single string which is then transmitted to monitoring / control room. At the receiving end, the necessary data can be extracted from the transmitted string by using the respective decompression technique. A MATLAB based system is developed which can produce the compressed string corresponds to input voltage & frequency which can be decoded to obtain the voltage & frequency at the receiving end.

A novel DCSK communication scheme for PLCC based DAS

With the increasing popularity of power line communication technologies, modifications over Spread Spectrum Technologies were made so as to develop a suitable alternative for power line communication. Differential Code Shift Keying (DCSK) is one such technology developed by Yitran Technologies & patented on May 16th, 2000. In this paper, it is proposed to develop this DCSK Communication Scheme which can be used for PLCC system for DAS application.

A novel data compression approach to reduce string size for PLCC based DAS

MATLAB based DCSK communication scheme developed for PLCC based DAS requires longer time of execution at receiving end particularly with longer strings. In order to avoid the problem, basic arithmetic coding based lossless data compression method is proposed which can reduce the string size of string and consequently improve the performance of the system significantly. As conventional DAS deals mostly with integer values only, the algorithm is developed for integer string only. But this proposed method can be modified suitably and can be implemented for character strings successfully.

A novel Huffman coding based approach to reduce the size of large data array

While dealing with large data array required in various applications, the memory required for the data storage and data transfer of that bulk data becomes difficult. If the array size can be reduced without losing the data, the problem of storage and data transfer can be avoided. In this paper, a Huffman Coding based data compression algorithm is proposed and tested in MATLAB environment which will significantly reduce the size of one dimensional data array. Though the algorithm is tested with number array only, the algorithm can be extended to be applied with character array with slight modification.

Development of DBEA Compressed Data Transfer System over Power Line

Data transfer is extremely important in any Data Acquisition System (DAS). Power system operation involves enormous volume of data transfer between field devices (or generating stations) and data centre (or Load Despatch Centre). Data compression is an extremely popular in communication as there is a reduced energy requirement for transferring compressed information. Power line communication is still in operation for data transfer between different substations and Differential Code Shift Keying (DCSK) modulation scheme is extremely popular in the majority of the available power line communication modems. Differential Binary Encoding Algorithm (DBEA) is a low computational approach which can give high compression ratio with repetitive slow varying data array. As majority of available data can be compressed successfully, this work focuses on the development of DBEA compressed data transfer system suitable to transfer data over power line. At the encoding end, a large data array corresponding to different practical data is compressed by DBEA before transferring the string through DCSK. From the superchirp being obtained, compressed string is extracted and is decoded to obtain actual data array at decoding end. As DBEA is implemented and tested successfully at low level microcontrollers, it is possible to extend this work for practical applications.

Adaptive Huffman Coding-Based Approach to Reduce the Size of Power System Monitoring Parameters

For maintaining power system stability, several parameters like voltage, frequency, etc. are monitored sequentially at regular intervals by SCADA, and the informations are transmitted to data centre through suitable communication schemes. If the volume of data can be reduced, then it is possible to reduce the energy and space requirement. This paper emphasizes on the development of an algorithm to compress the monitoring parameters using Adaptive Huffman Coding in MATLAB environment. The compression ratio obtained by this approach is better than what is obtained by other data compression techniques. This results in the reduction of memory requirement by about 60%, thereby enabling it suitable for the data handling of a large volume of monitoring data encountered frequently in a power system.

Basic Arithmetic Coding Based Approach to Compress a Character String

Data compression plays an important role for storing and transmitting text or multimedia information. This paper refers to a lossless data algorithm is developed in C-platform to compress character string based on Basic Arithmetic Coding. At the preliminary stage, this algorithm was tested for the character array comprising of vowels only and the probability distribution is assumed arbitrarily. The result being obtained is encouraging with compression ratio far beyond unity. Though the algorithm was tested for vowels only but the work can be extended for any character array with probability of distribution as obtained from the survey of few randomly selected articles.

Comparison of the performance of DCSK for PLCC with and without data compression

Differential Code Shift Keying (DCSK) communication scheme a modified version of spread spectrum technology meant for power line carrier communication (PLCC). In power line conditions, this modulation scheme has its own advantages over other conventional modulation techniques. Development of DCSK scheme in MATLAB environment to transmit character string suffers with longer superchirp length particularly for increased string length. This problem is eliminated by compressing the data string by employing Basic Arithmetic Coding and Huffman Coding based compression before transferring the information employing DCSK. In this paper, the performances for all the developed algorithms are compared to determine the advantages and drawbacks of algorithms.