Telephonic communications – Substation or terminal circuitry – For loudspeaking terminal
Reexamination Certificate
2005-12-20
2005-12-20
Isen, Forester W. (Department: 2644)
Telephonic communications
Substation or terminal circuitry
For loudspeaking terminal
C379S388060, C379S390010, C379S406070
Reexamination Certificate
active
06978009
ABSTRACT:
A near full duplex portable handset speakerphone comprises: a microprocessor; a hands-free receive register connected to the microprocessor; a hands-free transmit register connected to the microprocessor; a ROM having a speakerphone operation algorithm, the ROM connected to the microprocessor; a first analog-to-digital converter connected to the hands-free receive register; a second analog-to-digital converter connected to the hands-free transmit register; a first programmable digital attenuator connected to the microprocessor and to a speaker; and a second programmable digital attenuator connected to the microprocessor and to a microphone, wherein near full duplex communication is achieved without digital signal processing. In another feature of the invention, the hands-free registers provide a digital representation of the speech volume in each direction to the microprocessor. The microprocessor monitors the speech signal levels, calculates digital volume comparisons in order to make speech gain decisions for optimal sound, and digitally adjusts the gains in the two speech paths to the upper half of their maximum values.
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Isen Forester W.
Legerity Inc.
Swerdlow Daniel
LandOfFree
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