The signal quality of holographic memory is greatly lowered by the pixel mismatch between the charge-coupled device (CCD) and the reproduced image caused by image distortion. This paper discusses an approach to improve the signal quality by using two step decoding method. By this method, first, distortion correction is done to improve the degree of pixel mismatch to obtain better signal to noise ratio (SNR). Then, to eliminate errors such as noise that cannot be removed by distortion correction, soft decision Viterbi decoding using the newly defined reliability is used to correct errors. The effectiveness of this two step decoding method was tested by computer simulation, and its effect to improve SNR and reduce errors was confirmed.
In recent years, the possibility of applying process bus technology in accordance with IEC 61850 and IEC 61869 standards for protection relay systems has been investigated as a method of reducing the bulk of metallic cables in the substation environment and to support the digital transformation of power grid field data. Conventional process bus system sampling synchronization is enabled using dedicated devices for synchronization control, and hence the system is highly dependent upon the dedicated devices, which causes challenges in the durability, reliability, and cost aspects. Therefore, in this paper, we propose a new configuration method for the process bus using a synchronous sampling scheme based upon oversampling and high-speed publishing rate of the sampled value frame. Subsequently, we discuss the validity and efficacy of the proposed method. Moreover, we present the interoperability test results using prototype stand-alone merging units and intelligent electric devices from three vendors.
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