MODEM DEVICE AND PB TONE SIGNAL DETECTION CIRCUIT

Japanese Patent JP3644724

B2

PURPOSE: To easily select any transmission mode with a simple circuit configuration while providing several transmission mode functions.
CONSTITUTION: A calling signal is received and when this signal is 1100Hz, its band is passed through a filter 14a. When it is detected by a comparator 14c, a detected signal is applied to a circuit 20. This detected signal is applied to a circuit 2. When a 697Hz signal and a 1209Hz signal are received from a counter device as PB signals simultaneously with the reception of this detected signal, the 697Hz signal passes its band through a filter 11a and detected by a comparator 11c and applied to a decoder 19. The 1209Hz signal passes its band through a filter 15a and is detected by a comparator 15a and applied to the decoder 19. It is recognized from these detected signals by the decoder 19 that the code of the PB signal is (1) and a figure code and a PB detect signal are applied to the circuit 2. The circuit 2 selects the facsimile transmission mode function while considering the signal at 1100Hz as well.

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Mitsuyuki Shun

JP13772095A

May 11, 2005

June 05, 1995

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Oki Electric Industry Co., Ltd.

H04L27/26; H04Q1/45; (IPC1-7): H04Q1/45; H04L27/26

JP55151885A
JP55050764A
JP6189015A

Nobuyuki Kudo

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