| 摘要 |
<p>PURPOSE:To enable a synchronizing signal to be obtained by a simple constitution under the state that the signal is not transmitted by obtaining the synchronizing signal based on a noise signal from a noise signal output means under the state that the signal is not transmitted. CONSTITUTION:Under the state that a receiving signal does not exist, only the noise signal is supplied to an AGC amplifier 2 from the noise output circuit 5. Then, as the AGC amplifier 2 is changed to a high gain state under that state, the noise signal is amplified and supplied to a narrow-band filter 3. As a signal of which frequency is nearly the same as that of the synchronizing signal is contained in the noise signal, the signal of which frequency is neraly the same as that of the synchronizing signal is outputted by the narrow-band filter 3. This signal is converted to a digital signal by a comparator 4 and used as the synchronizing signal in a receiving device. Thus the signal corresponding to the synchronizing signal can be obtained under the state that the receiving signal does not exist.</p> |
