| 摘要 |
PURPOSE:To perform stabilized communication by keeping synchronization even in low receiving conditions, by controlling the threshold level of a synchronizing detector according to the condition of receiving. CONSTITUTION:When shifted to tracking mode, an input signal Vd for a synchronizing detection circuit 10 is inputted to a memory 14 and a terminal 19 of a differential amplifier 5'. The memory 14 picks up the max. value of the signal Vd to input to the other terminal 20 of the amplifier. Since voltages inputted to the terminals 19 and 20 of the amplifier 5' are equal to each other in the effective area of an AGC, the output of the amplifier is zero. Therefore, a controlling part 16 does not operate, and the threshold level voltage Vs of a circuit 13 for setting threshold level continues to be the previous value. However, if enters the ineffective area of the AGC, the signal Vd lowers to induce voltage in the output of the amplifier 5' that lowers the voltage Vs through the control part 16. As a result, a code error rate is not deteriorated, and better communication is realized even in the ineffective area of the AGC. |
