Phone with adjustable sidetone
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United States of America Patent
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-
Nov 21, 2000
Grant Date -
N/A
app pub date -
Oct 30, 1997
filing date -
Oct 30, 1997
priority date (Note) -
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status (Latency Note)
Importance
Abstract
A telephone with a selectable level of sidetone for use in noisy environments. The selectable level of sidetone is achieved by forming a switch-controlled feedback path including a gain setting resistor from the output of a transmit amplifier in a hybrid circuit to a summing node virtual ground at one input of a differential amplifier driving the handset speaker. The summing node is also coupled to the audio output port of the three port hybrid so as to also receive incoming audio signals from the tip and ring lines. A microcontroller having configuration data controls whether the switch is closed and the feedback path exists or the switch is open and no feedback occurs. Lower sidetone or no sidetone is useful in phones used in noisy environments such as factory floors or restaurants.
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Family
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