Bandwidth (signal processing)

About: Bandwidth (signal processing) is a research topic. Over the lifetime, 48550 publications have been published within this topic receiving 600741 citations. The topic is also known as: Bandwidth (signal processing) & bandwidth.

Information handling systems with broadband and narrowband communication channels between repository and display systems

Abstract: A bidirectional or unidirectional information handling system for data exchange and distribution. The system includes a data repository system and a data display system. The systems are linked for data exchange by a broadband channel for unidirectional high data flow rates and, in some embodiments, by a narrowband channel for bidirectional lower data flow rates. The display system may take a number of forms, including personal communications assistants, desktop personal computers, and set top boxes. The data communication channels may be defined by a number of different protocols and bandwidth segments and may be wireline or wireless.

Balanced Coupled-Resonator Bandpass Filters Using Multisection Resonators for Common-Mode Suppression and Stopband Extension

Abstract: Novel fourth-order balanced coupled-resonator bandpass filters are proposed using suitably designed half-wavelength (lambda/2) multisection resonators for common-mode suppression. By properly designing the input/output (I/O) resonators associated with the filter composed of four bi-section resonators, a balanced filter with good common-mode suppression is realized, but its rejection bandwidth is rather limited. To widen the rejection bandwidth, the I/O bi-section resonators are replaced by the tri-section ones so that a balanced filter with good common-mode suppression and wide rejection bandwidth may be realized by suitably arranging the composed bi-/tri-section resonators. Specifically, a stopband-extended balanced filter with good common-mode suppression (>50 dB) within the differential-mode passband is implemented and its stopbands are also extended up to 5f0 d with a rejection level of 30 dB, where f0 d is the center frequency in differential-mode operation.

High-Bandwidth Multisampled Digitally Controlled DC–DC Converters Using Ripple Compensation

Abstract: This paper investigates multi sampled digitally controlled switched-mode power supplies with switching ripple compensation. In digital controllers for power converters, the main bandwidth limitations come from A/D conversion time, computational delays, and small-signal delay of the digital pulsewidth modulator (DPWM). In hard-wired digital-controller technologies, such as in dedicated digital IC and/or in field-programmable gate arrays (FPGAs), the calculation delays can be made negligible with respect to the switching period; thus, when fast ADCs are used, the overall phase lag is dominated by the DPWM. The multi sampling approach can strongly reduce the DPWM delay, thus breaking the bandwidth limitations of conventional single-sampled solutions. In this paper, the additional aliasing effects, which would require a filtering action, are avoided, exploiting the periodic nature of the switching ripple under steady-state conditions using a repetitive-based filtering action. Simulation and experimental results on a 1.2-V-10-A 500-kHz synchronous buck converter, where the digital control has been implemented in the FPGA, confirm the properties of the proposed solution.

Improved constant-frequency hysteresis current control of VSI inverters with simple feed-forward bandwidth prediction

Abstract: An improved implementation of the constant-frequency hysteresis current control of three-phase voltage-source inverters is presented A simple, self-adjusting analog prediction of the hysteresis band is added to the phase-locked-loop control to ensure constant switching frequency, even at a high rate of output voltage change, such as required in active filters, fast drives and other highly demanding applications This provision also improves the relative position of phase modulation pulses, thus reducing the current ripple The prediction method is robust and uses a small number of inexpensive components It does not require trimming or tuning, giving the whole system the capability to adjust itself to different load conditions Thus, the control becomes suitable for hybrid or monolithic integration In this paper, the basic principles are described, and a detailed stability analysis is carried out The control performance is illustrated, both by simulated and experimental results

Fourier-domain beamforming: the path to compressed ultrasound imaging

Abstract: Sonography techniques use multiple transducer elements for tissue visualization. Signals received at each element are sampled before digital beamforming. The sampling rates required to perform high-resolution digital beamforming are significantly higher than the Nyquist rate of the signal and result in considerable amount of data that must be stored and processed. A recently developed technique, compressed beamforming, based on the finite rate of innovation model, compressed sensing (CS), and Xampling ideas, allows a reduction in the number of samples needed to reconstruct an image comprised of strong reflectors. A drawback of this method is its inability to treat speckle, which is of significant importance in medical imaging. Here, we build on previous work and extend it to a general concept of beamforming in frequency. This allows exploitation of the low bandwidth of the ultrasound signal and bypassing of the oversampling dictated by digital implementation of beamforming in time. By using beamforming in frequency, the same image quality is obtained from far fewer samples. We next present a CS technique that allows for further rate reduction, using only a portion of the beamformed signal's bandwidth. We demonstrate our methods on in vivo cardiac data and show that reductions up to 1/28 of the standard beamforming rates are possible. Finally, we present an implementation on an ultrasound machine using sub-Nyquist sampling and processing. Our results prove that the concept of sub-Nyquist processing is feasible for medical ultrasound, leading to the potential of considerable reduction in future ultrasound machines' size, power consumption, and cost.