| 摘要 |
PURPOSE:To evade channel interference by allowing a master equipment to select a free channel when a talk becomes unclear owing to interference, etc. CONSTITUTION:When the call button 29 of a slave equipment 2 is pushed, a frequency channel fA6 is sent out with a carrier. The master equipment 1 receives the channel fA6 and generates a ringing tone. In this case, when channels fA6 and fB6 are engaged by other interior interphones, the master equipment judges an interference state, so a channel change button 13 is pushed. Then, a channel change signal generator 14 operates to send out the channel fB6 with the carrier. The slave equipment 2 receives this signal and a PLL synthesizer 32 changes channels through a channel change signal detector 31 to obtain a frequency channel fA7. The master station 1 performs signal processing by a PLL synthesizer 14 and changes channel setting to obtain a channel FB7. |
