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This paper demonstrates the implementation of a QPSK/ time division multiple access (TDMA) narrowband (NB) satellite receiver using short preamble-based synchronization in the presence of timing, frequency and phase offsets, and with additive white Gaussian noise (AWGN). The narrowband satellite communication (NB-SATCOM) system, which is mostly preferred for low-rate data transfer, is primarily affected by large carrier frequency offset (CFO). The implemented receiver uses a 32-symbol short preamble for synchronization of time, large frequency and phase, and it gives better bit error rate (BER) performance at low energy per bit to noise density ratio (E b /N 0 ). As the proposed design uses short preamble, it is able to achieve a high level of spectral efficiency with less computational complexity. The functional verification of the synchronization algorithm is done using Matlab simulations and the algorithm implementation uses fixed-point C. The receiver design has been implemented for 24 TDMA channels in Texas Instruments (TI) multi-core C66x DSPs.

This paper demonstrates a multi-core DSP-based implementation of variable data rate OQPSK/time division multiple access (TDMA) satellite receiver in the presence of timing, frequency and phase offsets, and with additive white Gaussian noise (AWGN). The implemented receiver uses a 64-bit short preamble for synchronization. It operates at a variable symbol rate of 220Ksps to 660Ksps and gives better bit error rate (BER) performance at low energy per bit to noise density ratio (E b /N 0 ). The proposed receiver operates at a carrier frequency offset upto 15% value normalized to symbol rate. Matlab simulations are used for functional verification of the synchronization algorithm and fixed-point C is used for algorithm implementation. The receiver design is prototyped for 12 TDMA channels in Texas Instruments (TI) multi-core C66x DSPs. The design and implementation of this receiver have been done for C-DOT indigenous satellite project.

Real time system is a system in which the computation not only depends on producing a correct output, but the output should be delivered within predetermine timing constraint called deadline. As humans, we handle scheduling issues every day. For example, a student must accomplish homework by the appropriate due date, a professor must complete the rough draft of a paper by the submission date, etc., where we have only one task to accomplish, meeting that deadline probably would be very simple. Our lives, however, contain many tasks that have deadlines tax forms, car inspections, meetings, classes, etc. Thus, we must use some sort of scheduling technique to “juggle” our various tasks, so that they all are completed by their appropriate deadlines. As a result, many scholars develop different static and dynamic scheduling algorithms, which are best suited for both uniprocessor and multiprocessors. This paper work will focus on proposing a new dynamic scheduling algorithm. Because, it is found that the well-known uniprocessor dynamic scheduling (EDF (earlier deadline first) and LLF (least slack time first)) algorithms have many context switching and many probability of overhead occurrence (deadline-tie and laxity-tie respectively) which will degrade the performance of the whole system. The paper proposes a dynamic scheduling algorithm that has low context switching and totally reduce the probability of overhead occurrence by combining the deadline and slack to give priority for each task in the ready queue.

In the field of robotics, the two wheel mobile manipulator has the potential to perform wide range of applications. Balancing of the system becomes a bothering task due to the highly unstable nature of the system. Dynamics of wheeled mobile manipulator are derived by the basics of energy balance equation by approximating double inverted pendulum dynamics. Control method for balancing the two wheeled mobile manipulator using H-infinity controller (H∞) is discussed in the work. H-infinity control methods are developed to design systems which have the desired dynamic behavior and are robust with respect to perturbations. Settling time required to achieve stability of the system and maximum deviation from desired value using linear quadratic regulator (LQR) controller and H-infinity controller are compared. Designing and simulations are carried out to check the validity of the proposed method and the results prove the effectiveness of the proposed method.

Nowadays, Computer Networks tend to be large and diverse systems that communicate using wide selection of protocols. This complexity made the desire for more sophisticated tools to watch and troubleshoot network traffic. Network traffic monitoring is can be quite a network diagnostic tool that monitors local area networks and provides a graphical display of network statistics. While collecting information through the network's data stream, network monitor displays the source address of the computer that sent a frame onto the network, the destination address of the computer that received the frame and also the protocols employed to send the frame. The procedure through which network monitor collects this information is known as Capturing. Automatically, the network monitor gathers statistics on all of the frames it detects on the network into a capture buffer that is a reserved storage area in memory. To capture statistics on merely a specific subset of frames, we could discriminate these frames by designing a capture filter. To work with network monitor, the computer will need to have a network card that supports promiscuous mode. This paper targets on the usage of packet capturing library Jpcap for monitoring, analyzing and reporting Distributed Denial of Service (DDoS) Attacks.

Distributed Denial of Service (DDoS) attacks in the internet disrupts the availability of a service or resource. Massive Distributed DoS attacks have the potential to severely decrease backbone availability and can virtually detach a network from the Internet. Because of the seriousness of the problem many defense mechanisms have been proposed to combat these attacks. This paper presents a Multi-layered probabilistic model for DDoS attacks and evaluated the performance of the system. Furthermore, important features of each attack and defense system category are described and advantages and disadvantages of each proposed scheme are outlined. The goal of the paper is to place some order into the existing attack and defense mechanisms, so that a better understanding of DDoS attacks can be achieved and subsequently more efficient and effective algorithms, techniques and procedures to combat these attacks may be developed.

Drought affects hundreds of millions of people in the developing world and causes serious disruption of social and economic activities. Preparedness is better than relief and information is the backbone of drought preparedness. In this paper we report the results from a study in the use of GIS-derived products to assess micro-level drought vulnerability, taking a cluster of 17 villages in the South Central India as the study area. An internet-connected rural information center, linked to village knowledge centers, played a key role in testing the utility of this product, and the associated local-level predictions for seasonal rainfall.