Title:
COMMUNICATION SPEED CHANGEOVER DEVICE
Document Type and Number:
Japanese Patent JP3253916
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To surely transit a high speed signal reception mode into a low speed signal mode.
SOLUTION: Whether or not signals with frequencies of 1650 Hz, 1750 Hz and 1850 Hz whose energy is calculated by energy calculation circuits 4041-4043 through bad pass filters(BPF) 4031-4033 are received is discriminated. Low speed signals whose energy is calculated by the energy calculation circuits 4041-4043 are summed by an adder section 405. In this case, a discrimination circuit 406 starts its own timer. When the timer of the discrimination circuit 406 counts a prescribed time and the signals with the frequencies of 1650 Hz, 1750 Hz and 1850 Hz reach a prescribed energy, the signal is recognized as an EOP signal after a PIX signal. Thus, the device is controlled to be transited to the low speed signal reception mode.
Inventors:
Nobuhiko Noma
Keiji Egashira
Keiji Egashira
Application Number:
JP8253298A
Publication Date:
February 04, 2002
Filing Date:
March 13, 1998
Export Citation:
Assignee:
Matsushita Transmission System Co., Ltd.
International Classes:
H04N1/32; H04L25/02; H04L27/38; H04L29/08; H04N1/333; (IPC1-7): H04N1/32; H04L27/38; H04L29/08
Domestic Patent References:
| JP537674A | ||||
| JP8293992A | ||||
| JP1032704A | ||||
| JP10290351A | ||||
| JP8125711A | ||||
| JP6424534A | ||||
| JP1051508A | ||||
| JP2193428A | ||||
| JP63227228A | ||||
| JP6156536A | ||||
| JP5623066A | ||||
| JP61126396U |
Attorney, Agent or Firm:
Koichi Washida
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