| 摘要 |
<p>Radio telephone apparatus comprising a base unit 1 coupled to a wired telephone line 3, and a radio telephone set 2 including a battery and coupled to the base unit through a radio channel. The apparatus changes from a normal mode to a loudspeaker mode if the radio telephone set is adjacent to the base unit; this condition may be determined by monitoring a charging current from the base unit for the battery of the radio telephone set when the latter is installed in the base unit, or a switch operated by the radio telephone set being located in the base unit. In the normal mode, the wired telephone line is connected, via hybrid circuit, 4, to the transmitter 5 and receiver 8 of the base unit, in the loudspeaker mode, to a loudspeaker 38. The loudspeaker mode has two submodes: the loudspeaker-only mode or the loudspeaker-and-microphone mode, selected by a control switch 40 on the base unit. In the latter submode the wired telephone line 3 is also connected to the receiver in the base unit, and the connection from the wired telephone line to the loudspeaker is via a variable gain amplifier the gain of which is reduced if the microphone signal (as measured at the output of the receiver in the base unit) exceeds a predetermined level. The base unit continuously monitors the location of the base unit (and the state of the control switch, if present), and selects the mode accordingly.</p> |
