| 摘要 |
A modem connected to a telephone line and capable of preventing noise from being generating upon the modem being powered-on or reset includes a ring detector for receiving a ring signal associated with an incoming telephone call through the telephone line and converting the ring signal to a binary ring signal; a datapump for processing the incoming telephone call; a controller coupled to the datapump and responsive to the ring detector, for generating an off-hook signal upon the ring signal to be detected, the off-hook signal including a leading portion of a pulse type constituting noise; a noise eliminating circuit for eliminating the leading portion of a pulse type included in the off-hook signal; and a modem driver for driving the modem in response to the off-hook signal from the noise eliminating circuit to cause a remote computer to communicate with a local computer connected to the modem or to switch a calling telephone to communicate with a called telephone. By the use of the modem, an off-hook signal constituting noise can be eliminated, the noise occurring instantly upon the modem being powered-on or reset. Therefore, no noise is introduced into the telephone line while the telephone of one calling subscriber is connected to the telephone of a called subscriber.
|
