Telephone ring detector
First Claim
1. A telephone ring detector for detecting a ring signal voltage, said ring detector comprising:
- a voltage threshold setting device for establishing a voltage threshold and providing an output signal when said ring signal voltage exceeds said voltage threshold; and
a microprocessor responsive to said voltage threshold setting device, said microprocessor capable of measuring a time duration of said output signal and comparing said time duration with a predetermined time interval value, said microprocessor outputting a ring detection signal when said time duration exceeds said predetermined time interval value, said predetermined time interval being less than a ring cycle of said ring signal voltage.
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Accused Products
Abstract
A telephone ring detector detects a ring signal voltage from a diverse set of signals transmitted on a telephone line before a complete alternating current ring signal cycle is received. In an exemplary embodiment, the ring detector includes a voltage threshold setting device for establishing a voltage threshold and comparing the ring signal voltage to the voltage threshold to provide an output signal when the ring signal voltage is above the voltage threshold. A pair of zener diodes having a selected voltage value can provide the threshold setting and comparison functions. A microprocessor, including a timer for measuring a time duration of the output signal, outputs a ring detection signal when the time duration exceeds a predetermined time interval value, which is substantially less than a full ring cycle. A line switch responsive to the ring detector is provided to direct communication signals to a telecommunications device.
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Citations
24 Claims
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1. A telephone ring detector for detecting a ring signal voltage, said ring detector comprising:
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a voltage threshold setting device for establishing a voltage threshold and providing an output signal when said ring signal voltage exceeds said voltage threshold; and a microprocessor responsive to said voltage threshold setting device, said microprocessor capable of measuring a time duration of said output signal and comparing said time duration with a predetermined time interval value, said microprocessor outputting a ring detection signal when said time duration exceeds said predetermined time interval value, said predetermined time interval being less than a ring cycle of said ring signal voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A telephone ring detector for detecting a ring signal voltage, said ring detector comprising:
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a ring signal coupler having a blocking capacitor outputting said ring signal voltage to a current limiting resistor in series with said blocking capacitor; a voltage threshold setting device in series with said current limiting resistor, said voltage threshold setting device comprising a first zener diode in series with a second zener diode, each said zener diode having a voltage value of 39 volts; an opto-isolator in communication with said voltage threshold setting device, said opto-isolator providing an output signal when said ring signal voltage is above said voltage threshold; a microprocessor responsive to said opto-isolator, said microprocessor including a timer for measuring a time duration of said output signal of said opto-isolator, said microprocessor comparing said time duration with a preselected time interval value being less than 50 milliseconds, said microprocessor outputting a ring detection signal when said time duration exceeds said preselected time interval value; and a line switch having at least two output lines, said line switch receiving said ring detection signal from said microprocessor and directing communication signals to one of said at least two output lines.
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23. A method of detecting a telephone ring signal comprising:
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detecting a ring signal voltage; comparing said ring signal voltage to a predetermined threshold voltage; providing an output when said ring signal voltage exceeds said predetermined threshold voltage; measuring a time duration of said output; comparing said time duration to a predetermined time interval; and providing a ring detection output signal when said time duration of said output exceeds said predetermined time interval, said predetermined time interval being less than a ring cycle. - View Dependent Claims (24)
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Specification