Fundamental frequency

About: Fundamental frequency is a research topic. Over the lifetime, 8941 publications have been published within this topic receiving 131583 citations.

Efficient large-signal FET parameter extraction using harmonics

Abstract: An accurate and truly nonlinear large-signal parameter extraction approach is presented, using not only DC bias and fundamental frequency but also higher harmonic responses. The harmonic balance method for nonlinear circuit simulation, adjoint analysis for nonlinear circuit sensitivity calculation, and state-of-the-art optimization methods are applied. Improvements to the convergence of the optimization process are discussed. An automatic weight assignment algorithm enhancing parameter extraction is given. Numerical results demonstrate that the method is both theoretically and computationally feasible, i.e. it can uniquely and efficiently determined the parameters of the nonlinear elements of the GaAs MESFET model under actual large-signal operating conditions. Numerical results also show that under multibias, multipower inputs, and multifrequency excitations, spectrum measurements can effectively reflect the nonlinearities of the model and improve model reliability when they are used in nonlinear large-signal-model parameter extraction. >

Ultrasound imaging system and method based on simultaneous multiple transmit-focusing using weighted orthogonal chirp signals

Abstract: The present invention discloses an ultrasound imaging system and method which make a harmonic image of a good SNR (signal-to-noise ratio) by effectively removing fundamental frequency components through a pulse-compressing using the weighted chirp signals. The ultrasound imaging system includes: a transducer array for converting weighted chirp signals to ultrasound signals, and transmitting the ultrasound signals to a target object; a receiver for receiving signals reflected from the target object; a pulse-compressor for selectively pulse-compressing fundamental frequency components or harmonic frequency components in the reflected signals; and a producer for producing receive-focused signals from the pulse-compressed signals. Therefore, the ultrasound imaging system can form ultrasound image using the fundamental frequency components, and can form ultrasound harmonic image using the harmonic frequency components according to 2fo-correlation method or 2fo-correlation(PI) method.

Common mode & differential mode filter for variable speed drive

Abstract: Systems and methods for improved Variable Speed Drives having active inverters include an input filter for filtering common mode and differential mode currents. A three-phase inductor has three windings, each winding of the three-phase inductor having a center tap dividing each winding into a pair of inductor sections; and a three-phase input capacitor bank connected in a wye configuration to the three center taps at one end, and to a common point at the opposite end. The three-phase input capacitor bank provides a short circuit for frequencies above a predetermined fundamental frequency for shunting such frequencies through the three phase capacitor bank, while passing the predetermined fundamental frequency to an input AC power source.

Improved fundamental frequency coding in cochlear implant signal processing

Abstract: A new signal processing algorithm for improved pitch perception in cochlear implants is proposed. The algorithm realizes fundamental frequency (F0) coding by explicitly modulating the amplitude of the electrical stimulus. The proposed processing scheme is compared with the standard advanced combination encoder strategy in psychophysical music perception related tasks. Possible filter-bank and loudness cues between the strategies under study were minimized to predominantly focus on differences in temporal processing. The results demonstrate significant benefits provided by the new coding strategy for pitch ranking, melodic contour identification, and familiar melody identification.