Telephonic communications – Echo cancellation or suppression
Reexamination Certificate
2004-08-31
2008-09-23
Singh, Ramnandan (Department: 2614)
Telephonic communications
Echo cancellation or suppression
C379S406020, C379S406030, C379S406080, C375S222000
Reexamination Certificate
active
07428304
ABSTRACT:
A non-echo canceling voice band modem capable of detecting subscriber alerting signal (SAS) tones and customer premises equipment alerting signal (CAS) tones is provided. The modem includes a shaping filter, an analog-to-digital converter (ADC), a SAS tone detector, a CAS tone detector and an echo canceler. The shaping filter, which is located in a transmitting path of the modem, filters modem signals to be transmitted from the modem. The ADC, which is located in a receiving path of the modem, converts any incoming analog signal to corresponding digital signals to be used by the modem. The echo canceler, which is coupled to the SAS and CAS tone detectors, cancels any echoes in modem signals before sending said modem signals to the SAS and CAS tone detectors.
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Pai Narasimha
Patra Gopinath
Prabhakar Sheela
Dillon & Yudell LLP
Ng Anthony P.
Silicon Laboratories
Singh Ramnandan
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