1. Field of the Invention
The present invention relates to a cordless telephone apparatus having an antenna gain control circuit.
2. Description of the Related Art
Generally, a cordless telephone comprises a base station, which is connected to a wire telephone network, and a plurality of movable portable sets. The base station and the portable sets are connected to each other by a wireless or radio network. In the conventional cordless telephone apparatus, in a case where the portable set initiates a call, a predetermined key pad button is pressed in the portable set. A signal for setting a talking channel is then input into a control circuit of the movable portable set. A resultant talking channel setup is transmitted through an antenna via the wireless network to the base station.
The base station receives the transmitted radio signals from the portable set, and modulates the received signal. The modulated signal closes a line switch provided in a hybrid circuit via a baseband circuit of the base station. The wire telephone network and the base station are connected to each other by the line switch, and talking can be performed between the base station and the wire telephone over a line wire. The control circuit of the base station transmits a signal to the portable set by wireless, to indicate that the base station and the wire network are connected to each other.
In a case where telephone communications using two portable sets A and B are simultaneously performed, if the portable set A is positioned close to the base station and the portable set B is positioned further away from the base station, the base station receives a high field intensity radio signal from the portable set A and a low field intensity radio signal from portable set B. When the receiver of the base station receives the radio signal from the portable set B, its receiving sensitivity for the radio signal from portable set B is relatively the communication quality with the portable set B is accordingly worsened. The signal/noise may be deteriorated to the point that the base station cannot receive radio signals transmitted the portable set B and a connection between the portable set B and the base station will not be made.