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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Public Switched Telephone Network ： FOLDOC Public Switched Telephone Network (PSTN, T.70) The collection of interconnected systems operated by the various telephone companies and administrations ({telcos} and PTTs) around the world. Also known as the Plain Old Telephone System (POTS) in contrast to xDSL and ISDN (not to mention other forms of PANS). The PSTN started as human-operated analogue circuit switching systems (plugboards), progressed through electromechanical switches. By now this has almost completely been made digital, except for the final connection to the subscriber (the "last mile"): The signal coming out of the phone set is analogue. It is usually transmitted over a {twisted pair cable} still as an analogue signal. At the telco office this analogue signal is usually digitised, using 8000 samples per second and 8 bits per sample, yielding a 64 kb/s data stream (DS0). Several such data streams are usually combined into a fatter stream: in the US 24 channels are combined into a ). Several such data streams are usually combined into a fatter stream: in the US 24 channels are combined into a スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.