50 ghz spaced 25× 40 gbit/s wdm transmission over 560 km using smf-based large effective area fiber (leaf

Abstract In this paper, we present 50 GHz spaced 25 40 Gbit/s WDM transmission over 560 km using SMF-based Large Effective Area Fiber (LEAF) in a recirculating loop. The paper uses band-limited RZ signals carrying 2 31 -1 PRBS data, and shows that transmission distance of 560 km can be achieved with BER ≤ 10 -9 using 1 mW peak power and 4 ps pulse-width for each data signal. To attain this, optical filters with sharp transmission characteristics are used in both transmitter and receiver. The results demonstrated in this paper are based on simulation, and the author believes that the propagation distance reached in the paper is the longest distance achieved for such syste

Upgrading legacy long-haul WDM systems through unbalancing the proportion of 1s and 0s in the transmitted data

We present experimental results for wavelength-division multiplexed (WDM) transmission performance using unbalanced proportions of 1s and 0s in pseudo-random bit sequence (PRBS) data. This investigation simulates the effect of local, in time, data unbalancing which occurs in some coding systems such as forward error correction when extra bits are added to the WDM data stream. We show that such local unbalancing, which would practically give a time-dependent error-rate, can be employed to improve the legacy long-haul WDM system performance if the system is allowed to operate in the nonlinear power region. We use a recirculating loop to simulate a long-haul fibre system

Monitoring long distance WDM communication lines using a high-loss loopback supervisory system

In this paper, we present experimental results for monitoring long distance WDM communication links using a line monitoring system suitable for legacy optically amplified long-haul undersea systems. This monitoring system is based on setting up a simple, passive, low cost high-loss optical loopback circuit at each repeater that provides a connection between the existing anti-directional undersea fibres, and can be used to define fault location. Fault location is achieved by transmitting a short pulse supervisory signal along with the WDM data signals where a portion of the overall signal is attenuated and returned to the transmit terminal by the loopback circuit. A special receiver is used at the terminal to extract the weakly returned supervisory signal where each supervisory signal is received at different times corresponding to different optical repeaters. Therefore, the degradation in any repeater appears on its corresponding supervisory signal level. We use a recirculating loop to simulate a 4600 km fibre link, on which a high-loss loopback supervisory system is implemented. Successful monitoring is accomplished through the production of an appropriate supervisory signal at the terminal that is detected and identified in a satisfactory time period after passing through up to 45 dB attenuation in the loopback circuit

Electric Circuit Analysis Using a Simple Assumption-Based Technique

Abstract This paper demonstrates a simple technique to analyze linear electric circuits. The technique is based on assuming some voltage or current values according to the given resistance/impedance values such that a relative circuit performance is obtained. The actual circuit results are achieved directly by normalizing the assumed values using a specific formula. In practice, this method either reduces the number of simultaneous equations or simplifies the mathematical formulas; hence the overall analysis procedure is reasonably accelerated. It is highly recommended that this method is taught in electric circuit courses especially in the beginning chapters so that students can have more variety of circuit analysis techniques. It is also possible to apply such a method to verify an existing solution or vice versa