Title:
TELEPHONE LINE-NETWORK REPEATING DEVICE
Document Type and Number:
Japanese Patent JP3478941
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To eliminate malfunction caused by a signal which travels round by removing the frequency component of a busy tone by a filter from the signal outputted from a voice recording and reproducing circuit.
SOLUTION: The band-pass filter 3 removes the frequency component of the busy tone to prevent the busy tone frequency component from traveling round from T to R of a hybrid transformer 4. Namely, if a telephone line side disconnects a held telephone call, the busy tone is inputted from the telephone line 8. This busy tone is sent to a special sound detecting circuit 6 through the hybrid transformer 4 and R. At this time, a holding tone is also put together with the traveling-round busy tone by the hybrid transformer 4. The band-pass filter 4, however, removes the frequency component of the busy tone from the holding tone to the line, so the special sound detecting circuit 6 can recognize the busy tone of the opposite party without misrecognizing it and a telephone line control circuit 9 indicates the disconnection of the line to a hooking circuit 5, so that the line is disconnected.
Inventors:
Taizo Haruna
Yoji Mukuta
Hiroshi Takigami
Yoji Mukuta
Hiroshi Takigami
Application Number:
JP9553297A
Publication Date:
December 15, 2003
Filing Date:
April 14, 1997
Export Citation:
Assignee:
株式会社日立製作所
株式会社日立インフォメーションテクノロジー
株式会社日立インフォメーションテクノロジー
International Classes:
H04M1/00; H04L12/02; H04M1/58; H04M3/00; H04M11/00; H04Q3/58; (IPC1-7): H04M3/00; H04L12/02; H04M1/00; H04M1/58; H04M11/00
Domestic Patent References:
| JP548690A |
Attorney, Agent or Firm:
Yasuo Sakuta (1 outside)
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