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.

Principles of space-time array processing for ultrawide-band impulse radar and radio communications

Abstract: The emerging ultrawide-band (UWB) impulse technology has found numerous applications in the commercial as well as the military sector. The rapid technological advances have made it possible to implement (cost-effective, short-range) impulse radar and impulse-radio communication and localization systems. Array beamforming and space-time processing techniques promise further advancement in the operational capabilities of impulse radar and impulse-radio communications to achieve long-range coverage, high capacity and interference-free quality of reception. We introduce a realistic signal model for UWB impulse waveforms and develop the principles of space-time array processing based on the signal model. A space-time resolution function (STRF), a space-frequency distribution function (SFDF) and a monopulse-tracking signal are derived for impulse waveforms received by a self-steering array beamforming system. The directivity peak-power pattern and energy pattern of the beamformer are also derived. Computer plots of the STRF, SFDF and the beam patterns are obtained. The directivity beam patterns of impulse waveforms are sidelobe-free and, therefore, there is no need for sidelobe suppression via amplitude weighting of the array elements. Also, the resolution angle for the beam patterns is derived as a decreasing function of array size and frequency bandwidth. Electronic beamsteering based on slope processing of monopulse waveforms is described.

Comparison between computed and measured bandwidth of quarter-wave microstrip radiators

Abstract: A simple theory based on a cavity model is used to analyze a quarter-wavelength flat element, without a dielectric substrate, which is connected to the ground plane in one of its sides by a metallic wall. The bandwidth of the element is computed from this model. Very good agreement is obtained between the computed and the measured bandwidth for elements in the S-band. >

Gain measurement and monitoring for wireless communication systems

Abstract: A method of monitoring an element in wireless communication system is provided. An operational noise measurement is obtained by measuring a noise value outside of a bandwidth of a first device, but within a bandwidth of a second, subsequent device. The operational noise measurement is alternatively obtained by tuning an input band of the element to shift the input band partially or completely outside of a bandwidth of a first device to create an open band or by suppressing an input of the antenna and measuring noise within the open bandwidth of the element of the wireless communication network. A stored parameter is retrieved and compared to the measured operational noise. Alternatively, a leakage signal of the element may be received at a signal receiver and compared to a reference. The reference is a function of components of the wireless communication system in a leakage path of the leakage signal.

Implementation of a foveated image coding system for image bandwidth reduction

Abstract: We have developed a preliminary version of a foveated imaging system, implemented on a general purpose computer, which greatly reduces the transmission bandwidth of images. The system is based on the fact that the spatial resolution of the human eye is space variant, decreasing with increasing eccentricity from the point of gaze. By taking advantage of this fact, it is possible to create an image that is almost perceptually indistinguishable from a constant resolution image, but requires substantially less information to code it. This is accomplished by degrading the resolution of the image so that it matches the space-variant degradation in the resolution of the human eye. Eye movements are recorded so that the high resolution region of the image can be kept aligned with the high resolution region of the human visual system. This system has demonstrated that significant reductions in bandwidth can be achieved while still maintaining access to high detail at any point in an image. The system has been tested using 256 by 256 8 bit gray scale images with a 20 degree field-of-view and eye-movement update rates of 30 Hz (display refresh was 60 Hz). users of the system have reported minimal perceptual artifacts at bandwidth reductions of up to 94.7% (a factor of 18.8). Bandwidth reduction factors of over 100 are expected once lossless compression techniques are added to the system.

DFT-Spread OFDM for Fiber Nonlinearity Mitigation

Abstract: We study the transmission performance of the recently proposed multiband discrete-Fourier-transform spread orthogonal frequency-division multiplexing (MB-DFT-S-OFDM) format in which each subband is in essence a single-carrier signal with Nyquist bandwidth. We have found that the optimal subband bandwidth for a 428-Gb/s MB-DFT-S-OFDM signal is 15 and 3 GHz for inline dispersion compensated (IDC) and nondispersion compensated (NDC) fiber links, respectively. The optimized MB-DFT-S-OFDM outperforms the coherent single-carrier by 1 dB (0.8 dB) after 1000-km transmission over IDC (NDC) links.