| 摘要 |
<p>PURPOSE:To prevent the deviation of transmission/reception timings generated when a reception electric field level declines by comparing a detected electric field level with a threshold value and outputting a compared result as the changeover signals of clock signals. CONSTITUTION:A reception part 1 smooths an intermediate frequency IF to be defined as the level information of a reception electric field and outputs it to a level comparator circuit 3. The circuit 3 compares the electric field level information outputted from the reception part 1 with the preset threshold value and sends clock changeover signals to a clock synchronization circuit 2 so as to respectively output synchronous clock signals when an electric field level value is higher and free-running clock signals when the threshold value 15 higher. A timing control circuit 5 inputs the clock signals outputted from the circuit 2 and outputs the transmission/reception timing control signals of data to the reception part 1 and a multiplexing/demultiplexing circuit 4. By this constitution, even when the electric field level of reception radio waves declines and the phase of the clock signals is disturbed, the deviation of the timings of the operation of the circuit 4 can be surely prevented.</p> |
