Communication device

Details Communication device Communication device

1995-07-28

1999-06-22

Woo, Stella

Telephonic communications

Telephone line or system combined with diverse electrical...

Having transmission of a digital message signal over a...

379 9331, 379 9334, 379556, 379557, H04M 1100

Patent

active

059150025

ABSTRACT:
When a type of a connected channel is to be detected, a CPU of a communication device sets a channel in an off-hook state by closing a channel closing section, and an existence of the DC current supplied through the cable channel is detected based on an output from a DC current detecting circuit. The CPU sets the connected channel in the off-hook state by switching a switching section to the radio channel, and detects an existence of a dial-tone signal transmitted through the radio channel via a modem. The CPU determines which one of the cable channel and the radio channel is connected to the communication device, or none of them are connected. The described arrangement enables an automatic detection of a type of a connected channel without using a special adaptor for each channel that is required in the conventional communication device provided with the automatic detecting function of the type of the channel, and also enables a reduction in cost and size of the communication device.

REFERENCES:
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patent: 4991197 (1991-02-01), Morris
patent: 5353334 (1994-10-01), O'Sullivan
patent: 5428671 (1995-06-01), Dykes et al.
patent: 5524047 (1996-06-01), Brown et al.
patent: 5602902 (1997-02-01), Satterlund et al.
patent: 5790656 (1998-08-01), Rahamim et al.

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