| 摘要 |
<p>PURPOSE:To realize the digital transmitter-receiver with a short polling interval in the polling system transmitter-receiver employing the frequency hopping system. CONSTITUTION:A signal from a main station is mixed with a local signal at a reception circuit 20 via an antenna 18 and a high frequency changeover device 19 and a demodulation circuit 20 demodulates a data. A hopping pattern signal from the main station is subject to synchronization acquisition by a synchronization acquisition circuit 24, and a synchronization hold circuit 25 applies synchronization holding to the signal based thereon to control a hopping pattern generating circuit 23 to control a local signal generating circuit 22. A synchronization holding discrimination circuit 26 checks the synchronization holding state after a prescribed time to control a hopping pattern generating circuit 23 so as to omit the succeeding synchronization holding when the synchronization holding is consecutive. When the synchronization holding state is valid up to a succeeding synchronization holding time, the succeeding synchronization acquisition is omitted and polling is implemented immediately, then the polling interval is reduced.</p> |
