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The unit cells are usually backed by a ground plane, and the incident wave reflects off them towards the direction of the beam, but each cell adds a different phase delay to the reflected signal. A phase distribution of concentric rings is applied to focus the wavefronts from the feeding antenna into a plane wave (to account for the varying ...
In radio communication, multipath is the propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection and refraction, and reflection from water bodies and terrestrial objects such as mountains and buildings.
The sound waves usually reflect off the wall and interfere with other sound waves that are generated later. To prevent sound waves reflecting directly to the receiver, a diffusor is introduced. [16] A diffusor has different depths in it, causing the sound to scatter in random directions evenly.
In acoustics, acoustic dispersion is the phenomenon of a sound wave separating into its component frequencies as it passes through a material. The phase velocity of the sound wave is viewed as a function of frequency. Hence, separation of component frequencies is measured by the rate of change in phase velocities as the radiated waves pass ...
In audio systems, parasitic oscillations can sometimes be heard as annoying sounds in the speakers or earphones. The oscillations waste power and may cause undesirable heating. For example, an audio power amplifier that goes into parasitic oscillation may generate enough power to damage connected speakers. A circuit that is oscillating will not ...
The human brain can handle this sort of auditory source separation problem, but it is a difficult problem in digital signal processing. This problem is in general highly underdetermined, but useful solutions can be derived under a surprising variety of conditions. Much of the early literature in this field focuses on the separation of temporal ...
The spatial sound field in the recording room consists of the direct wave of the acoustic source and a spatially distributed pattern of mirror acoustic sources caused by the reflections by the room surfaces. Reducing that spatial mirror source distribution onto a few transmitting channels causes a significant loss of spatial information.
Another technique used to increase isolation is to use an isolated subframe. This splits the system with an additional mass/spring/damper system. This doubles the high frequency attenuation rolloff, at the cost of introducing additional low frequency modes which may cause the low frequency behaviour to deteriorate. This is commonly used in the ...