| 摘要 |
PURPOSE:To know that another slave equipments is in communication at a look, to prevent a transmitting circuit from being operated by mistake, and to prevent the generation of radio interference, by operating annunciating circuits of respective slave equipments while some slave equipment is in communication with a master equipment. CONSTITUTION:The master equipment is connected to a telephone circuit and radio communication between the master equipment and plural slave equipments each provided with a receiving circuit 9 and a transmitting circuit 8 is performed. The circuit 9 of every slave equipment is provided with an IF signal detecting circuit 29 and a voice output control circuit 28 which amplifies a call signal selectively. Further, a circuit monitoring circuit 36 which monitors output signals of both circuits 28 and 29 is provided. The annunciating circuit 32 consisting of a transistor 30 and a light emitting diode 31 is provided on the output side of the circuit 36 and the annunciating circuit 32 is controlled by the output of the circuit 36. Then the output of the circuit 36 goes to a level H by the output of the circuit 28 in communication of some slave equipment to radiate the diode 31, thus annunciating the state that other slave equipments are in communication. Consequently, erroneous operation of the circuit 8 by a hook switch 35 is eliminated to prevent radio interference. |
