We propose and experimentally demonstrate a chirp-free carrier-suppressed optical pulse generator using a simple and cost-effective approach. An 80-GHz carrier-suppressed optical pulse train was successfully obtained by using two cascaded 20-GHz clock-driven dual-drive Mach-Zehnder modulators. Compared with the conventional scheme using 40-GHz clock driving signal to generate an 80-GHz pulse train, the proposed scheme is cost-effective and scalable to high repetition rate pulse generation by using low-speed devices.
By introducing a Nyquist filter, we have successfully reduced a data signal bandwidth without intersymbol interference and transmitted a polarization-multiplexed 1Gsymbol/s, 64QAM(12Gbit/s) coherent signal over 150km in an optical bandwidth of 1.5GHz.
In this paper, we propose a new fixed-lag maximum likelihood smoother with a finite impulse response (FIR) structure for discrete-time state-space models. This smoother is called a maximum likelihood FIR smoother (MLFS). The MLFS is linear with the most recent finite outputs and does not require a prior initial state information on a receding horizon. It is shown that the proposed MLFS possesses the unbiasedness property and the deadbeat property. Simulation study illustrates that the proposed MLFS is more robust against uncertainties and faster in convergence than the conventional fixed-lag Kalman smoother.
This paper presents a robust global localization method using Artificial Neural Network (ANN) to learn sonar sensor patterns associated to points in a specified area. Given a set of unseen sonar sensor readings, the ANN is capable of predicting the corresponding point in the map accurately even with the presence of small random noises. This technique can also be extended into the dynamic environment by simply cascading two ANN and incorporating a suitable filtering algorithm (FA) for preprocessing data purposes. Thereafter, after filtering out the corrupted components based on the information disseminate from the FA module, a FeedForward Network (FFN) is used to make the prediction after training with sufficient filtered epochs.
Within-die process variation increases with technology scaling in nanometer era. Due to uncorrelated random variations in the threshold voltage (Vth), neighboring transistors in a 6-T SRAM have different Vth and dissipate different subthreshold leakages. Since 3 transistors leak when the cell stores a 1 and the other 3 leak when it stores a 0, total cell leakage depends on its stored value. Using Monte Carlo simulations, we show that this difference averages 46% at a variation of 58% in Vth. This phenomenon can be used to reduce leakage of SRAM-based memories by value control.
This paper presents a novel design of large shift registers to overcome the problem of I/O pin bottleneck typically encountered in FPGA implementation. The proposed design uses an embedded logic recursively to decompose and synthesize the shifter operations. Compared to the conventional logic shifter, barrel shifter, and logarithmic shifter designs, the proposed approach reduces the number of I/O pins by at least 89%, and increases the available logic slices by 215%. The performance of the design is optimized by using a hybrid clocking scheme and is easily extended to multi-chip FPGA implementation.
Most of the methods proposed so far for numerical analyses of all-optically regenerated transmission systems have problems either in strictness or in simplicity, which are trade-off. In this paper, a new statistic approach is proposed, which is based on probability distribution functions (PDFs) of transmitted signals and a transfer function of an all-optical regenerator. The method is simple since complicated calculation of the device dynamics is not necessary, while it is strict as the conversion of PDF by the nonlinear transfer function is rigorously calculated.