| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a terrestrial digital transmission apparatus without a risk of failure in SFN transmission, even when a delay time set to an OFDM type transmission apparatus is changed. Ž<P>SOLUTION: The terrestrial digital transmission apparatus in a system switching a transmission facility between an active side and a standby side includes two systems of transmission facilities with numbers 1 and 2 containing delay devices 3A and 3B for SFN transmission, and controls a coaxial switching appliance 7 by a switching controller 9. In the terrestrial digital transmission apparatus, a delay-time monitor device 20 computing the transmission time of signals from output of OFDM modulators 1A and 1B to that of BPFs 6A and 6B and monitoring the delay time is mounted. In the terrestrial digital transmission apparatus, the switching controller 9 is supplied with a delay-time alarm and switching between the active side and the standby side in the transmission facility is carried out when the delay time reaches a preset decision value or more. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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