EP0299507A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Electronic telephone terminal having noise suppression function
Assignee: Fujitsu Ltd
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Filing: 1988-07-15
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Granted: —
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Expires: 2008-07-15
Abstract
Abstract An electronic telephone terminal having a transmitter (1) and a receiver (2), both having an approximately linear acoustic-to-electric transduction characteristics, and having a surrounding noise suppression function, and including a variable attenuator (12) for controlling a gain of a transmission system; a noise detection device (3) for detecting surrounding noise; and a control device (63) for controlling the variable attenuator (12) in such a manner that when a sound pressure level input to the transmitter (1) exceeds a predetermined threshold value, the gain is fixedly set to a constant value, and when the input sound pressure level is equal to or below the predetermined threshold level, the gain is controlled in response to a change in the surrounding noise level detected by the noise detection device (3).
Inventors
- 👤 Juro Ohga
- 👤 Kensaku Fujii
- 👤 Hiroyuki Masuda
- 👤 Yuka Sato
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 03:44
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/08; H04M9/085
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
129 words
An electronic telephone terminal having a handset including a transmitter (1) and a receiver (2), both having an approximately linear acoustic-to-electric transduction characteristics, and having a surrounding noise suppression function, comprising: a variable attenuator (12) for controlling a gain of a transmission system; a noise detection means (3) for detecting surrounding noise; and a control means (63) for controlling said variable attenuator (12) in such a manner that when a sound pressure level input to said transmitter (1) exceeds a predetermined threshold value, said gain is fixedly set to a constant value, and when said input sound pressure level is equal to or below said predetermined threshold level, said gain is controlled in response to a change in said surrounding noise level detected by said noise detection means (3).
Claim 2
Dependent Claim
129 words
An electronic telephone terminal having a handset including a transmitter (1) and a receiver (2), both having an approximately linear acoustic-to-electric transduction characteristics, and having a surrounding noise suppression function, comprising: a variable attenuator (12) for controlling a gain of a transmission system; a noise detection means (3) for detecting surrounding noise; and a control means (63) for controlling said variable attenuator (12) in such a manner that when a sound pressure level input to said transmitter (1) exceeds a predetermined threshold value, said gain is fixedly set to a constant value, and when said input sound pressure level is equal to or below said predetermined threshold level, said gain is controlled in response to a change in said surrounding noise level detected by said noise detection means (3).
Claim 3
Dependent Claim
27 words
An electronic telephone terminal as claimed in claim 1, wherein said noise detection means (3) is a microphone (3) mounted at a side opposite to said handset.
Claim 4
Dependent Claim
77 words
An electric telephone terminal as claimed in claim 1, wherein said control means (63) controls said variable attenuator (12) in such a manner that when said surrounding noise level is high, a variable portion of said gain of said transmission system is set to a lower value than said constant value, and when said surrounding noise level is low, said variable portion of said gain is set to a value in the vicinity of said constant value.
Claim 5
Dependent Claim
65 words
An electronic telephone terminal as claimed in claim 1, wherein said control means (63) controls said variable attenuator in such a manner that when said surrounding noise level is high, said gain of a reception system including said receiver is set to a high value, and when said surrounding noise level is low, said gain of said reception system is set to a constant value.
Claim 6
Dependent Claim
69 words
An electronic telephone terminal as claimed in claim 1, wherein a loudspeaker (5) is provided as said receiver (2) for a loudspeaking telephone terminal, and said gain of said reception system is controlled in such a manner that when said surrounding noise level is high, said gain is set to a high value, and when said surrounding noise level is low, said gain is set to a constant value.
Claim 7
Dependent Claim
42 words
An electronic telephone terminal as claimed in claim 1, wherein said transmitter (1) is a microphone (4) for a loudspeaking telephone terminal, and said microphone (4) is used not only as said transmitter (1) but also as said noise detection means (3).
Claim 8
Dependent Claim
186 words
An electronic telephone terminal having a handset including a transmitter (1) and a receiver (2), both having an approximately linear acoustic-to-electric transduction characteristics, and having a surrounding noise suppression function, comprising: a variable attenuator (12) for controlling a gain of a transmission system; a noise detection means (3) for detecting surrounding noise; a level detection means (101) for detecting an average sound pressure level of a signal output from said noise detection means (3), and deciding a gain characteristic in response to a detected noise level; and a control means (63) for controlling said variable attenuator (12) in such a manner that when a sound pressure level input to said transmitter (1) exceeds a predetermined threshold value, said gain is fixedly set to a constant value, and when said input sound pressure level is equal to or below said predetermined threshold level, said gain is controlled in response to a change in said surrounding noise level detected by said noise detection means (3), and further, said control means (63) controls said variable attenuator (12) based on said gain characteristic decided by said level detection means (101).
Claim 9
Dependent Claim
186 words
An electronic telephone terminal having a handset including a transmitter (1) and a receiver (2), both having an approximately linear acoustic-to-electric transduction characteristics, and having a surrounding noise suppression function, comprising: a variable attenuator (12) for controlling a gain of a transmission system; a noise detection means (3) for detecting surrounding noise; a level detection means (101) for detecting an average sound pressure level of a signal output from said noise detection means (3), and deciding a gain characteristic in response to a detected noise level; and a control means (63) for controlling said variable attenuator (12) in such a manner that when a sound pressure level input to said transmitter (1) exceeds a predetermined threshold value, said gain is fixedly set to a constant value, and when said input sound pressure level is equal to or below said predetermined threshold level, said gain is controlled in response to a change in said surrounding noise level detected by said noise detection means (3), and further, said control means (63) controls said variable attenuator (12) based on said gain characteristic decided by said level detection means (101).
Claim 10
Dependent Claim
51 words
An electronic telephone terminal as claimed in claim 7, wherein said control means (63) controls said gain characteristic of said variable attenuator (12) decided by said level detection means (3) in such a manner that when the noise level becomes larger, the noise suppressing effect of the input sound becomes greater.
Claim 11
Dependent Claim
41 words
An electronic telephone terminal as claimed in claim 7, wherein said control means (63) controls said variable attenuator (12) in such a manner that when the detected noise level becomes higher, the attenuation start level at said gain characteristic becomes higher.
Claim 12
Dependent Claim
46 words
An electronic telephone terminal as claimed in claim 7 wherein said control means (63) controls said variable attenuator (12) in such a manner that when the detected noise level becomes higher, the maximum attenuation quantity and the attenuation start level at said gain characteristic becomes larger.
Claim 13
Dependent Claim
39 words
An electronic telephone terminal as claimed in claim 7, wherein said control means (63) controls said variable attenuation in such a manner that when the detected noise level becomes higher, an attenuation slope of said gain characteristic becomes greater.
Claim 14
Dependent Claim
49 words
An electronic telephone terminal as claimed in claim 7, wherein said control means (63) controls said variable attenuator (12) in such a manner that when the detected noise level becomes higher, at least two of said attenuation start level, said maximum attenuation quantity, and said attenuation slope become larger.
References Cited (Backward Citations)
No citation records indexed.
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