Telephonic communications – Subscriber line or transmission line interface – Hybrid circuit
Reexamination Certificate
2006-11-21
2006-11-21
Tran, Sinh (Department: 2615)
Telephonic communications
Subscriber line or transmission line interface
Hybrid circuit
C379S390010
Reexamination Certificate
active
07139393
ABSTRACT:
A level of a sound signal including a voice signal and an environmental noise signal is detected and a level (power level) is sampled in response to a clock signal. It is detected whether the presently sampled level increases from the previously sampled level. An environmental noise level is estimated such that, when the presently sampled level increases from the previously sampled level, difference between the presently and previously estimated environmental noise levels is lower than a predetermined value. When the presently sampled level decreases, the presently estimated environmental noise level is equalized to the presently sampled value. The environmental noise level is estimated only when the detected level is smaller than the predetermined value. The sampling interval may be smaller than 250 msec. Estimation may be stopped in the presence of voice signal. An environmental noise level may be estimated when the detected level is smaller than a reference. A communication apparatus and data terminal including the An environmental noise level estimation apparatus are also disclosed.
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Briney III Walter F
Matsushita Electric - Industrial Co., Ltd.
Tran Sinh
Woo Louis
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