| 摘要 |
<p>Dialling apparatus for telephone numbers of subscribers and of public call boxes in a data transmission network, comprising means for establishing and for breaking the loop of a telephone line, means for furnishing at an output terminal at least one continuous signal when the telephone set receives an arbitrary tone to be identified and an input terminal for controlling the means for establishing and for breaking the loop, and a microprocessor receiving and sampling the said continuous signal and furnishing control signals to the said input terminal. It is characterised in that it identifies the interrupted tones by searching for the specified surface of the plane x=E (duration of the tone pulse) y=S (duration of the silence between two tone pulses) in which the point representing the tempo of the tone is located. <IMAGE></p> |
