This paper proposes a set of higher-order modified moments as alternative objective criteria for pitch extraction and explores the impact of the speech window length on pitch estimation error. To obtain the Kth order modified moment, each speech frame is split into a positive-valued signal and a negative-valued signal. The magnitudes of the Kth order moments for the positive and the negative valued signals are obtained and combined. The proposed objective criteria form a relatively sharp peak around the true pitch value compared to the correlation function. For calculation of errors, pitch reference (`ground truth') values are calculated from manually-corrected estimates of the periods obtained from laryngograph signals. The results obtained for the third order modified moment are compared with the results for correlation and magnitude difference criteria and the YIN method. The modified moments provide improved pitch accuracy with less occurrence of large errors (e.g. half or double pitch estimation errors)
This paper investigates micromachined antenna performance operating at 5 GHz for radio frequency (RF) energy harvesting applications by comparing different substrate materials and fabrication modes. The research aims to discover appropriate antenna designs that can be integrated with the rectifier circuit and fabricated in a CMOS (Complementary Metal-Oxide Semiconductor)-compatible process approach. Therefore, the investigation involves the comparison of three different micromachined antenna substrate materials, including micromachined Si surface, micromachined Si bulk with air gaps, and micromachined glass-surface antenna, as well as conventional RT/Duroid-5880 (Rogers Corp., Chandler, AZ, USA)-based antenna as the reference. The characteristics of the antennas have been analysed using CST-MWS (CST MICROWAVE STUDIO®—High Frequency EM Simulation Tool). The results show that the Si-surface micromachined antenna does not meet the parameter requirement for RF antenna specification. However, by creating an air gap on the Si substrate using a micro-electromechanical system (MEMS) process, the antenna performance could be improved. On the other hand, the glass-based antenna presents a good S11 parameter, wide bandwidth, VSWR (Voltage Standing Wave Ratio) ≤ 2, omnidirectional radiation pattern and acceptable maximum gain of >5 dB. The measurement results on the fabricated glass-based antenna show good agreement with the simulation results. The study on the alternative antenna substrates and structures is especially useful for the development of integrated patch antennas for RF energy harvesting systems.
The paper deals with the growing interest of energy harvesting systems due to great development in many new emerging technologies in electronics and telecommunication. The research focuses particularly about rectenna element comprises of antenna, impedance matching and rectifier. The rectenna is applied under Micro-Electromechanical-System (MEMS) technology design use in Radio Frequency (RF) energy harvester. MEMS is a technology of miniaturization that has been mostly adopted from integrated circuit industry together on a chip that are made using micro fabrication technique and applied for not only electrical systems. RF ambient source is considered over other ambient sources because RF can be broadcasted by various wireless systems in unlicensed frequency bands. However, the amount of energy captured from the ambient RF is extremely low which need improvements and more Direct Current (DC) voltage generated from RF energy harvester. For this motivation, a dual band MEMS rectenna is proposed for maximizing the efficiency. Power Management Unit (PMU) is interposed between MEMS rectenna and a load. The system is equipped with temporary energy storage and voltage regulator to produce optimum output voltage. The paper proposes a system that is designed and simulated using PSpice software and modeled in Mentor Graphic. The stated result from RF MEMS energy harvester is to provide functional conversion efficiency and reliable energy harvesting system to reach 1.5-3.0 V output voltage for operating frequency at 1.9 and 2.45 GHz from RF input power at -20 dBm with reveal approximately 100% improvement over other existing designs. The conceptual design can be the platform for innovative developments in recent technologies to achieve wireless transmission powered only by RF MEMS energy harvester.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.