Special Loudspeaker Drivers for Low-Frequency Bandwidth Extension

2005 ◽  
pp. 129-144
Keyword(s):  
Low Frequency ◽  
Frequency Bandwidth ◽  
Bandwidth Extension

Low-frequency bandwidth extension of telephone speech using sinusoidal synthesis and Gaussian mixture model

2011 ◽  
Author(s):  
Hannu Pulakka ◽  
Ulpu Remes ◽  
Santeri Yrttiaho ◽  
Kalle J. Palomäki ◽  
Mikko Kurimo ◽  
...  
Keyword(s):  
Gaussian Mixture Model ◽  
Mixture Model ◽  
Low Frequency ◽  
Gaussian Mixture ◽  
Frequency Bandwidth ◽  
Bandwidth Extension ◽  
Telephone Speech

Detection of Transformer Faults Using Frequency-Response Traces in the Low-Frequency Bandwidth

2014 ◽  
Vol 61 (9) ◽  
pp. 4971-4978 ◽  
Author(s):  
Wilder Herrera Portilla ◽  
Guillermo Aponte Mayor ◽  
Jorge Pleite Guerra ◽  
Carlos Gonzalez-Garcia
Keyword(s):  
Frequency Response ◽  
Low Frequency ◽  
Frequency Bandwidth

scholarly journals A Design of Dual Broadband Antenna in Mobile Communication System

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Jianming Zhou
Keyword(s):  
Mobile Communication ◽  
Communication System ◽  
High Frequency ◽  
Microstrip Line ◽  
Low Frequency ◽  
Dielectric Substrate ◽  
Frequency Bandwidth ◽  
Broadband Antenna ◽  
Feeding Method ◽  
Frequency Unit

A design of dual broadband antenna is proposed in this paper; it consists of one low frequency unit and two high frequency units. The low frequency unit consists of a pair of printing vibrators; the high frequency unit consists of a pair of printing oscillators, which is bent at its end, and high frequency unit and low frequency unit are set on the same dielectric substrate. Through adding a parasitic unit on antenna, it can enhance frequency bandwidth without affecting the bandwidth. In the high frequency unit, it adopts gap-coupled microstrip line feeding method in order to get enough bandwidth. Through the test of dual broadband antenna, it can be found that, in the low frequency part, the antenna covers 20% bandwidth of the total bandwidth, and it covers the frequency from 800 MHz to 980 MHz. In the high frequency, the antenna covers 60% of total bandwidth and its frequency is from 1540 MHz to 2860 MHz, so the designed antenna can satisfy the frequency requirements of 2G/3G/LTE (4G) communication system.

scholarly journals Full-waveform inversion with extrapolated low-frequency data

Geophysics ◽  
2016 ◽  
Vol 81 (6) ◽  
pp. R339-R348 ◽  
Author(s):  
Yunyue Elita Li ◽  
Laurent Demanet
Keyword(s):  
Waveform Inversion ◽  
Low Frequency ◽  
Velocity Model ◽  
Propagation Model ◽  
Full Waveform Inversion ◽  
Frequency Data ◽  
Local Minima ◽  
Bandwidth Extension ◽  
Low Frequencies ◽  
Full Waveform

The availability of low-frequency data is an important factor in the success of full-waveform inversion (FWI) in the acoustic regime. The low frequencies help determine the kinematically relevant, low-wavenumber components of the velocity model, which are in turn needed to avoid convergence of FWI to spurious local minima. However, acquiring data less than 2 or 3 Hz from the field is a challenging and expensive task. We have explored the possibility of synthesizing the low frequencies computationally from high-frequency data and used the resulting prediction of the missing data to seed the frequency sweep of FWI. As a signal-processing problem, bandwidth extension is a very nonlinear and delicate operation. In all but the simplest of scenarios, it can only be expected to lead to plausible recovery of the low frequencies, rather than their accurate reconstruction. Even so, it still requires a high-level interpretation of band-limited seismic records into individual events, each of which can be extrapolated to a lower (or higher) frequency band from the nondispersive nature of the wave-propagation model. We have used the phase-tracking method for the event separation task. The fidelity of the resulting extrapolation method is typically higher in phase than in amplitude. To demonstrate the reliability of bandwidth extension in the context of FWI, we first used the low frequencies in the extrapolated band as data substitute, to create the low-wavenumber background velocity model, and then we switched to recorded data in the available band for the rest of the iterations. The resulting method, extrapolated FWI, demonstrated surprising robustness to the inaccuracies in the extrapolated low-frequency data. With two synthetic examples calibrated so that regular FWI needs to be initialized at 1 Hz to avoid local minima, we have determined that FWI based on an extrapolated [1, 5] Hz band, itself generated from data available in the [5, 15] Hz band, can produce reasonable estimations of the low-wavenumber velocity models.

Research on Conducted EMI in Power Converter

2012 ◽  
Vol 516-517 ◽  
pp. 1808-1811
Author(s):  
Bin Liang
Keyword(s):  
Electromagnetic Interference ◽  
High Frequency ◽  
Low Frequency ◽  
Power Converter ◽  
Power Electronic ◽  
Frequency Bandwidth ◽  
Differential Mode ◽  
Three Phase ◽  
Electronic Switches ◽  
Conducted Emi

This paper researches differential mode (DM) conducted electromagnetic interference (EMI) in rectifier. The DM interference source generated by power electronic switches is given. Based on experimental and theoretical analysis, the conducted EMI of a three-phase rectifier is studied systematically. The study shows that it changes with resistance loads in low frequency ranges, while in high frequency bandwidth, the effect of change of the resistance load on the DM EMI is not obvious. The validity of the models is confirmed by the measurements.

Sign in / Sign up

Export Citation Format

Share Document