In this work we design and build an optoelectronic demultiplexer to distribute audio and video signals transmitted through an optical carrier toward different users using a liquid crystal display (LCD) as a router. The output plane of our proposed device is located within the Fresnel Diffraction regime. With this feature we obtain a simultaneous distribution, high-speed of processing, easiness of path reconfigurations and a high density of interconnections. The optical carrier modulation includes a Frequency Shift Keying signal (FSK) to indicate the interconnection path. This last control signal is manipulated with a personal computer. We present some preliminary results of the feasibility of our proposal.
High speed remote radio control of systems containing multiple elements is usually performed using control channels for individual elements with multiple emitters and receivers at different conduits. If this signals are multiplexed and transmitted the bandwidth of each individual channel is reduced depending on the number of required channels. We propose a hybrid system that allows demultiplexing on flight time using a spatial light modulator to route the
incoming signal into different out ports. The control signals are first multiplexed in frequency and a low speed routing control signal modulates it in amplitude. The combined signal is used to drive a diode laser. The proposed demultiplexing apparatus consists on a double 4f optical system in which the image of a dynamic liquid crystal display is imaged on the Fresnel plane. The control signal displays an amplitude binary mask on the dynamic spatial light modulator to route the signals to individual detectors located at the Fresnel plane in order to recover the individual channels. Afterward each channel is individually recovered. In order to demonstrate this system, multiple CATV signal were multiplexed with a digital control signal used to amplitude modulate the diode laser and tested on an optical bench. We also present the advantages of using such optical interconnects on the Fresnel plane over the Fraunhoffer plane.
This paper describes a texture coding technique mainly suitable for segmentation-based coding schemes. The main features of the proposed technique are its efficiency in terms of bits per pixel for homogeneous regions and its ability to deal with local inhomogeneities that may be present in the image. The basic idea of the coding strategy is to divide the image into blocks and to classify the blocks in two categories: Referable and Nonreferable. Referable means that the block can be approximated by one block of the already transmitted texture and nonreferable is defined by opposition. Nonreferable blocks are transmitted with a general purpose coding scheme (for example a DCT-based technique) and referable blocks are transmitted by means of a simple transition vector indicating which sample of the transmitted texture has to be translated. We show that this technique is suitable for texture but produces distortions for strong contours. As a result, we propose to use it within a segmentation-based coding scheme where contours are transmitted by another strategy. Finally, the application to sequence coding is discussed. It is shown that this technique is particularly attractive to code the prediction error within a motion compensated video coding scheme.
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