| 摘要 |
The telephone has a ROM storing multiple tone data for identifying a ringing phone out of a number of telephones in the same place like a working room. The tone generator comprises oscillator (1) operating only in on-hook state when it detects ringing signals, chord generator (10) connected to multiplexer (11), divider (2) giving 84 Hz signals to ring counter (7), counter (3) producing address signals from ROM (4), switch (5) selecting the signals from the output terminals of the ROM (4), and encoder (9) connected to a multiplexer generating tone signals for speaker (14) via filter (12) and amplifier (13).
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