| 摘要 |
<p>PURPOSE:To prevent a synchronization pattern from being hardly detected due to the decrease in a receiving level and increase in a bit error rate. CONSTITUTION:A synchronization pattern detecting means compares a bit string of a signal demodulated by a demodulator 3 after reception by a reception section 2 with a synchronization pattern and when a discordant bit number is less than a correlation threshold level, it is discriminated that the synchronization pattern is detected. The correlation threshold value is set by a decision device 10 based on a level of a received signal by a level measurement device 4 together with a bit error rate of a demodulated signal by a bit error rate computing element 8. When a consecutive detection frequency of a counted synchronization pattern reaches a backward protection stage number or over, a synchronization detecting frequency counter 18 discriminates that the synchronization is established. When the consecutive undetected frequency of the counted synchronization pattern reaches the forward protection stage number or over, the undetected frequency counter means 19 discriminates the synchronization is varnished. The protection stage number is set by forward and backward protection stage number decision devices 16, 17 based on the correlation threshold value.</p> |
