This paper presents an optimum receiver for direct detection/binary intensity modulation optical communication systems. Here, the signal‐plus‐noise model assumes a signal‐dependent nonstationary Gaussian random process. Moreover, assuming white noise and an ideal low‐pass receiver, the receiver vector is generated by sampling of signals and noise. The likelihood ratio for this receive vector is derived based on the maximum likelihood test to determine the structure of optimum receiver. This paper shows that the optimum receiver has both the usual correlation detection for additive noise in the radio wave region and noise energy detection for the signal shot noise. Next, the error rate of this receiver is derived theoretically and its characteristics are evaluated. As a result, the signal shot noise can be effectively utilized for signal detection by allowing a greater bandwidth for the receiver, elucidating treatment of the shot noise from the standpoint of statistical signal detection theory.
Surround Sound Composition in an indoor space is frequently provided with spatial sounds, giving both a sound localization and surround sound effect. Systems have been installed in public spaces such as a museum and retail shops. However, technical improvements are required to provide a small sweet spot and to address architectural designs for speaker installation, because multiple speakers are required for surround sound effect. Recently, we have been applying DSP beam-forming technology with a line-array speaker to create a 3D sound image by scanning a focused sound beam onto an interior surface. The DSP array speaker is capable of providing static and dynamic control in beam steering and sound focusing. Therefore, dynamic spatial sound effect on the interior surface is possible, wherein un-directional sound reproduction is analogous to un-directional lighting. We present three case studies; 1) Virtual 3D Surround Sound in multi-media improvisation, 2) 3D Spatial Sound Synthesis in sound installation and 3) Sound Installation with a Dynamic Sound Beam Scanning.
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