We report the characteristics of current induced frequency modulation (FM) for two continuous-wave quantum cascade lasers (QCLs) at 9.06 μm. Both the frequency tuning rate and the phase shift between intensity modulation and FM are measured at different modulation frequencies from 10 Hz to 200 kHz. The frequency tuning rate of the QCLs depends on both the modulation frequency and amplitude. The...

An approach to the joint estimation of sine-wave amplitude modulation (AM) and frequency modulation (FM) is described based on the transduction of frequency modulation into amplitude modulation by linear filters, being motivated by the hypothesis that the auditory system uses a similar transduction mechanism in measuring sine-wave FM. An AM-FM estimation algorithm is described that uses the amp...

The present study investigated the topography of epidurally recorded middle latency components P1 and N1 evoked by spectrally dynamic stimuli (linearly frequency-modulated (FM) tones) with respect to the tonotopic structure of the right primary auditory cortex, field AI. Whereas the gross topography corresponded to the spectral content of the FM tones, specific tonotopic offsets were found betw...

Fibromyalgia (FM) syndrome is characterized by chronic widespread pain, muscle tenderness and emotional distress. Previous studies found reduced endogenous pain modulation in FM. This deficiency of pain modulation may be related to the attributes of chronic pain and other clinical symptoms experienced in patients with FM. Thus, we tested whether there is a link between the clinical symptoms of ...

In this paper, we present a real-time amplitude-modulation frequency-modulation (AM-FM) analysis system, and apply the system to M-mode ultrasound video. The estimated frequency-modulation (fm) process is shown to capture the cardiac wall deformation, while the amplitude modulation process is shown to follow changes in cardiac wall material. Results from segmenting the septum and left-ventricle...

The National Ignition Facility (NIF) baseline configuration for inertial confinement fusion requires phase modulation for two purposes. First, 1A of frequency modulation (FM) bandwidth at low modulation frequency is required to suppress buildup of Stimulated Brioullin Scattering (SBS) in the large aperture laser optics. Also 3 A or more bandwidth at high modulation frequency is required for smo...

Detection thresholds were measured for a sinusoidal modulation applied to the modulation depth of a sinusoidally amplitude-modulated (SAM) white noise carrier as a function of the frequency of the modulation applied to the modulation depth (referred to as f'm). The SAM noise acted therefore as a "carrier" stimulus of frequency fm, and sinusoidal modulation of the SAM-noise modulation depth gene...

Complex natural sounds (e.g., animal vocalizations or speech) can be characterized by specific spectrotemporal patterns the components of which change in both frequency (FM) and amplitude (AM). The neural coding of AM and FM has been widely studied in humans and animals but typically with either pure AM or pure FM stimuli. The neural mechanisms employed to perceptually unify AM and FM acoustic ...

Frequency modulation (FM) information from the speech signal is herein proposed to complement the conventional amplitude based features for automatic forensic speaker recognition systems. In addition to presenting the AM-FM model of speech used to generate the proposed frequency modulation features, the significance of frequency modulation for speaker recognition is discussed. Evaluation result...

Responses of 99 cochlear nucleus cells and 24 cochlear nerve fibers were studied with FM signals; 14 cochlear nerve fibers and 57 cochlear nucleus cells were studied at four rates of modulation and several signal intensities. Classification of FM response patterns as symmetrical, asymmetrical, or unidirectional was based on the calculation of a symmetry factor (S), which compared the number of ...