نتایج جستجو برای: pulse frequency modulation
تعداد نتایج: 685581 فیلتر نتایج به سال:
A photonic approach to the simultaneous measurement of the frequency, pulse amplitude (PA), pulse width (PW), and time of arrival (TOA) of an unknown pulsed microwave signal is proposed and demonstrated. The measurement is performed based on optical carrier-suppressed modulation, complementary optical filtering, low-speed photodetection, and electrical signal processing. A proof-of-concept expe...
Implementation of Triangular Carrier based Space Vector Modulation for3-Ø Bridge Inverter using FPGA
The Space Vector Pulse Width Modulation (SVPWM) is used for three phase bridge Inverter to produce AC output voltage of desired magnitude and frequency. The purpose of controller is to produce regulated output voltage with low distortion under varying load conditions. A triangular carrier based space vector pulse width modulation is developed in MATLAB using Xilinx block set and executed in Fie...
The capacity of time-hopping pulse position modulation (PPM) and pulse amplitude modulation (PAM) for an ultra-wideband (UWB) communication system is investigated based on the multipath fading statistics of UWB indoor wireless channels. A frequency-selective fading channel is considered for both single-user and multiple-user UWB wireless systems. A Gaussian approximation based on the single-use...
A new mathematical treatment and algorithm for the design of |B1(+)|-selective RF excitation pulses is presented and validated. The algorithm is based on a rotated Shinnar-Le Roux pulse design algorithm, wherein the pulse's frequency modulation waveform is directly designed by the algorithm, and its amplitude and sign modulation waveform takes the place of the gradient field. A new pulse config...
We investigate the self-phase modulation (SPM) of a single-cycle terahertz pulse in a semiconductor, using bulk n-GaAs as a model system. The SPM arises from the heating of free electrons in the electric field of the terahertz pulse, leading to an ultrafast reduction of the plasma frequency, and hence to a strong modification of the terahertz-range dielectric function of the material. Terahertz...
The technique is suggested for a kind of pulse-width-modulation LED dimming in LED video displays. The significant increase of the gray levels number and image refresh frequency can be achieved when the large number of LEDs is controlled serially. The need for a large number of grayscale levels and high refresh rate is explained. The controlling data flow and the amount of buffer memory are the...
Pulsed ultrasound modulated optical tomography utilizing the harmonic response of lock-in detection.
Ultrasound modulated optical tomography (USMOT) can image the optical properties of a scattering medium at a spatial resolution approaching that of ultrasound (US). A lock-in parallel speckle detection technique is proposed to detect pulsed US modulated light using a multipixel detector. The frequency components of the pass band match those of the US pulse train and provide efficient detection....
This paper proposes a novel modulation scheme to reduce the harmonic content of voltages and currents caused by modular multilevel converters with embedded battery cell when employed for application in energy storage systems grid. The reduction total distortion (THD) is obtained injecting selected harmonics modulating wave phase disposition sinusoidal pulse width modulation. main innovation fre...
This paper presents a 4 kW, 450 kHz voltage-source inverter with a series resonant circuit for induction melting applications, which is characterized by the power control based on pulse density modulation (PDM). The pulse-density-modulated inverter makes an induction melting system simple and compact , thus leading to higher efficiency. A modulation strategy is proposed to realize the induction...
Orthogonal Frequency Division Multiplexing (OFDM) is a well-known modulation technique for transmission of large amount of digital data with high data rate in both wired and wireless communication systems. High peak-to-average power ratio (PAPR) is the main problem of OFDM system which can be improved by using single carrier frequency division multiple access (SC-FDMA) technique. The simulation...
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