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Externally attached handset of an end terminal used for mobile communication systems

  • US 5,452,474 A
  • Filed: 01/14/1994
  • Issued: 09/19/1995
  • Est. Priority Date: 10/14/1991
  • Status: Expired due to Fees
First Claim
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1. An externally attached handset, connected between an end terminal of a mobile communication system having a speaker/microphone terminal by which an externally attached speaker and microphone are connected and a data communication end terminal connected to the end terminal of the mobile communication system via the speaker/microphone terminal, which handset comprises:

  • a speaker signal line connecting said end terminal of said mobile communication system to said data communication end terminal via said speaker/microphone terminal;

    a microphone signal line connecting said end terminal of said mobile communication system to said data communication end terminal via said speaker/microphone terminal;

    a speaker, connected to said speaker signal line, converting a signal on the speaker signal line into an audio sound;

    a microphone, connected to said microphone signal line, converting a sound into a sound signal and supplying the sound signal to said microphone signal line;

    detecting means for detecting a called station identification signal and a data communication signal including a data communication protocol signal on said speaker signal line and on said microphone signal line; and

    an on/off circuit device, connected between said microphone and said microphone signal line, disconnecting said microphone from said microphone signal line when said called station identification signal is detected by said detecting means on said speaker signal line or on said microphone signal line, said on/off circuit device reconnecting said microphone to said microphone signal line while said microphone is disconnected and when said data communication signal has not been detected by said detecting means for a predetermined period of time.

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