| 摘要 |
<p>PROBLEM TO BE SOLVED: To actualize an OFDM transmission system which can accurately estimate a SWEEP symbol start position in any transmission state and always perform synchronous detection without being affected by whether or not a reflected wave and a noise component are present. SOLUTION: The digital transmitter which uses an orthogonal frequency- division multiplex modulation system transmitting multiple kinds of synchronous symbol groups and multiple data symbols as a signal of frame constitution calculates a reference threshold for detecting the end part of a no-signal period wherein frame synchronism in the synchronous symbol groups is detected from the maximum and minimum values of mean electric power values by 1/2-symbols periods of a receive signal in a specific period, so normal synchronization with a main wave can be actualized in a short time in any transmission state under wider-range conditions without being affected by whether or not a reflected wave and a noise component are present.</p> |
