Implementation of Optical OFDM Based System for Optical Networks

Orthogonal frequency division multiplexing (OFDM), a frequency division multiplexing scheme utilized as a digital multi-carrier modulation technique, implemented using optical fiber link for practical applications thereby developing optical OFDM using OptSim simulation. OFDM has many advantages over other modulation techniques such as a high resistance to inter-symbol interference (ISI) and it is robust against fading caused by multipath propaga­tion. Optical fiber cable (OFC) as a transmission media is used for distortion less transmission of data at a very higher data speed. OFC cable has a lot of advantages over other media. And OFDM over OFC cable will provide data speeds at a very high speed and with very less losses. In this work opti­cal transmitter and receiver for OFDM based optical network has designed for high speed data transmission over optical fiber. While modeling the sys­tem we have also used post,,pre and symmetric compensation technique to reconfigure the bandwidth along with add drop multiplexer,tunable filters and optical amplifiers to achieve high performance with minimum distortion and low bit error rate (BER).DOI:http://dx.doi.org/10.11591/ijece.v4i5.526

Simulation on probabilistic anti collision protocols of RFID using variable delay

In RFID System, it is important to avoid tag collision for identifying tag faster. In this paper, we proposed concept of variable delay for tag estimation & identification. The scheme is based on the Multi-level dynamic framed ALOHA protocol. Simulation results indicate that the time delay is added to each tag for avoiding collision. The main advantage of this is the delay is in microseconds which will not create problem of more time consumption

Opposed piston linear compressor driven two-stage Stirling Cryocooler for cooling of IR sensors in space application

A two-stage Stirling Cryocooler has been developed and tested for cooling IR sensors in space application. The concept uses an opposed piston linear compressor to drive the two-stage Stirling expander. The configuration used a moving coil linear motor for the compressor as well as for the expander unit. Electrical phase difference of 80 degrees was maintained between the voltage waveforms supplied to the compressor motor and expander motor. The piston and displacer surface were coated with Rulon an anti-friction material to ensure oil less operation of the unit. The present article discusses analysis results, features of the cryocooler and experimental tests conducted on the developed unit. The two-stages of Cryo-cylinder and the expander units were manufactured from a single piece to ensure precise alignment between the two-stages. Flexure bearings were used to suspend the piston and displacer about its mean position. The objective of the work was to develop a two-stage Stirling cryocooler with 2 W at 120 K and 0.5 W at 60 K cooling capacity for the two-stages and input power of less than 120 W. The Cryocooler achieved a minimum temperature of 40.7 K at stage 2. (C) 2017 Elsevier Ltd. All rights reserved