FDM hierarchy - FDM hierarchy

Japanese: FDMハイアラーキ - エフディーエムハイアラーキ（英語表記）FDM hierarchy

In frequency division multiplexing (FDM), group modulation is used when the degree of multiplexing is high, and group modulation is also repeated by combining several groups. This hierarchical structure of multiplexing is called the FDM hierarchy. For example, in the Japanese public telephone network, 12 call channels are grouped together as the basic group, five groups of basic groups are grouped together as the basic supergroup, five groups of basic supergroups are grouped together as the basic main group, and three groups of basic main groups are grouped together as the basic supermain group. Therefore, these groups contain call paths of 12, 60, 300, and 900 channels, respectively.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

周波数分割多重通信(FDM)において，多重度が多い場合には群変調が用いられ，さらにいくつかの群をまとめて群変調を繰り返すことも行われる。この多重化の階層構成をFDMハイアラーキという。例えば日本の公衆電話網においては，12通話チャンネルをまとめて基礎群とし，基礎群を5群まとめて基礎超群，さらに基礎超群を5群まとめて基礎主群，基礎主群を3群まとめて基礎超主群と呼んでいる。したがって，これらの群はおのおの12,60,300,900チャンネルの通話路を含むことになる。

出典　株式会社平凡社世界大百科事典第２版について　情報

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