ITE Transactions on Media Technology and Applications
Online ISSN : 2186-7364
ISSN-L : 2186-7364
Volume 9, Issue 3
Displaying 1-6 of 6 articles from this issue
Special Section on Data Storage and Related Technologies
Regular Section
  • Tadaaki Isobe, Yuya Takimoto, Ryosuke Harakawa, Masahiro Iwahashi
    2021 Volume 9 Issue 3 Pages 169-179
    Published: 2021
    Released on J-STAGE: July 01, 2021

    This paper develops a system to visually inspect cutlery based on a simple machine learning algorithm using image features that are robust against overexposure. First, we develop an image acquisition apparatus comprising a laser and a screen that produces speckle images of unique shapes depending on the degree to which the photographed cutlery has been polished. The contribution of this study is to produce speckle images in this way. This enables accurate classification without newly deriving a sophisticated machine learning algorithm in the subsequent processing. We use the speckle images to develop moment-related features that represent the unique shapes and avoid the problem of overexposure. Second, we apply the extreme learning machine, a simple but representative machine learning algorithm, to the obtained features. Experimental results using real cutlery show that our developed system achieved good accuracy and precision regardless of exposure time.

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  • Shingo Asakura, Tomoaki Takeuchi, Kohei Kambara, Masahiro Okano
    2021 Volume 9 Issue 3 Pages 180-187
    Published: 2021
    Released on J-STAGE: July 01, 2021

    We are developing an advanced Integrated Services Digital Broadcasting-Terrestrial (ISDB-T) system for the next generation of digital terrestrial television broadcasting. The advanced ISDB-T provides 4K8K terrestrial broadcasting service for fixed reception and 2K service for mobile reception simultaneously within one channel. New technologies such as Low-Density Parity-Check (LDPC) code are used for expanding the transmission capacity and for improving the spectral efficiency. The LDPC codes designed for the advanced ISDB-T have two code lengths and 13 code rates for each code length. The code length and code rate can be selected in consideration of the transmission latency requirement or the link budget. Meanwhile, although the LDPC codes have good bit error rate (BER) performance approaching the Shannon limit, a small number of error bits cause an error floor even if the Es/N0 is high enough. The error floor may cause serious issues such as block noise in video and mute in audio because broadcasting is a real-time service without any feedback. To deal with this problem, Bose-Chaudhuri-Hocquenghem (BCH) code is concatenated as outer code to the LDPC codes as inner codes. We conducted a simulation using a field programmable gate array (FPGA) instead of a computer to evaluate the BER performance. An FGPA simulation is 1000 times faster than a computer simulation, so the BER performance can be evaluated quickly with an adequate number of measurement bits. As a result, it was confirmed that LDPC codes perform as designed both in the water-fall and error-floor regions and that the BCH codes correct the small number of error bits after the LDPC decoder.

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