Apparatus for sending a ringing signal and data with reduced impulse noise
First Claim
1. An apparatus for sending a ringing signal to notify a called terminal of the presence of an incoming call addressed the, comprising:
- ringing voltage generating means for generating a ringing voltage;
ringing signal sending means for sending out a ringing signal over a subscriber line by outputting the ringing voltage with a predetermined duty cycle of a ringing period and a silent period;
data transfer means for performing a data transfer to the called terminal over the subscriber line during one of the silent periods;
feed impedance selection means working in conjunction with one or more switches to select a low-impedance feed voltage in the one of the silent periods during which the data transfer is performed, and selecting the a high-impedance feed voltage in the other silent periods during which no data transfer is performed; and
feed impedance setting means for providing the high-impedance feed voltage to the subscriber line when said feed impedance selection means selects feeding of the high-impedance feed voltage, wherein the high-impedance feed voltage is realized by inserting a predetermined resistance on the subscriber line in series with a subscriber line circuit (SLIC) that drives the subscriber line, while the low-impedance feed voltage is provided by removing the predetermined resistance from the subscriber line.
1 Assignment
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Accused Products
Abstract
An apparatus which produces a ringing signal for a telephone system, effectively suppressing impulse noises. A ringing voltage generator produces a ringing voltage. A ringing signal sending unit sends a ringing signal to the called telephone terminal over the subscriber line by outputting the ringing voltage intermittently. This ringing signal consists of ringing periods and silent periods which will appear alternately with a prescribed duty cycle. One of those silent periods is used by a data transfer unit used to transport data to the called terminal. A feed impedance setting unit provides a feed voltage with higher source impedance. A feed impedance selection unit selects a low-impedance feed voltage in the one of the silent periods during which a data transfer is performed, and selects a high-impedance feed voltage in the other silent periods during which no data transfer is scheduled.
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Citations
8 Claims
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1. An apparatus for sending a ringing signal to notify a called terminal of the presence of an incoming call addressed the, comprising:
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ringing voltage generating means for generating a ringing voltage;
ringing signal sending means for sending out a ringing signal over a subscriber line by outputting the ringing voltage with a predetermined duty cycle of a ringing period and a silent period;
data transfer means for performing a data transfer to the called terminal over the subscriber line during one of the silent periods;
feed impedance selection means working in conjunction with one or more switches to select a low-impedance feed voltage in the one of the silent periods during which the data transfer is performed, and selecting the a high-impedance feed voltage in the other silent periods during which no data transfer is performed; and
feed impedance setting means for providing the high-impedance feed voltage to the subscriber line when said feed impedance selection means selects feeding of the high-impedance feed voltage, wherein the high-impedance feed voltage is realized by inserting a predetermined resistance on the subscriber line in series with a subscriber line circuit (SLIC) that drives the subscriber line, while the low-impedance feed voltage is provided by removing the predetermined resistance from the subscriber line. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for sending a ringing signal to inform a caller of the presence of an incoming call addressed thereto, comprising:
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ringing voltage generating means for generating a ringing voltage;
ringing signal sending means for sending out a ringing signal over a subscriber line by outputting the ringing voltage with a predetermined duty cycle of a ringing period and a silent period;
feed impedance selection means working in conjunction with one or more switches to select a high-impedance feed voltage in the silent period to drive the subscriber line; and
feed impedance setting means for providing the high-impedance feed voltage to the subscriber line when said feed impedance selection means selects feeding of the high-impedance feed voltage, wherein the high-impede feed voltage is realized by inserting a predetermined resistance on the subscriber line in series with a subscriber line circuit (SLIC) that drives the subscriber line. - View Dependent Claims (7)
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8. An apparatus for sending a ringing signal to notify a called terminal of the presence of an incoming call addressed thereto, comprising:
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a ringing voltage generator to generate a ringing voltage;
a ringing signal sender to send out a ringing signal over a subscriber line by outputting the ringing voltage with a predetermined duty cycle of a ringing period and a silent period;
a data transfer unit to perform a data transfer to the called terminal over the subscriber line during one of the silent periods;
a switch controller to control one or more switches;
a feed impedance selector working in conjunction with said switch controller to select a low-impedance feed voltage in the one of the silent periods during which the data transfer is performed, and selecting the a high-impedance feed voltage in the other silent periods during which no data transfer is performed, said selection based on said control of said one or more switches; and
a feed impedance setting unit to provide the high-impedance feed voltage to the subscriber line when said feed impedance selection means selects feeding of the high-impedance feed voltage, wherein the high-impedance feed voltage is realized by inserting a predetermined resistance on the subscriber line in series with a subscriber line circuit (SLIC) that drives the subscriber line, while the low-impedance feed voltage is provided by removing the predetermined resistance from the subscriber line.
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Specification