Personal computer having a sound card
First Claim
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1. A Telephone Device for the Deaf (TDD) transitive adapted for TDD signaling and associated with a computer, the TDD transitive comprising:
- a) a sound processor adapted to receive a digital audio signal and generate a transmit audio signal, wherein said sound processor is a sound card adapted to sample an analog signal to generate said digital audio signal and interface with a computing system, said sound card having a first audio input and a first audio output;
b) a correlator provided in the computer and adapted to discriminate between at least two audio tone states found in said digital audio signal and to output a received data stream signal, wherein said correlator discriminates between said at least two audio tone states a number of times per bit time slot, said correlator determining bit values based on a count of said audio tone states discriminated; and
c) a Plain Old Telephone Service (POTS) connector adapted to connect said first audio input and said first audio output to a local loop and to match an impedance of a local loop to an impedance of said first audio input and to an impedance of said first audio output.
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Abstract
Telephone Device for the Deaf (TDD transitive) for a computing system and method of encoding and decoding TDD signals are described. The apparatus includes a sound card enabled to transmit and receive TDD coded Frequency Keying modulated audio signals. In extracting characters from a received audio signal, the sound card is used to sample the received audio signal. In extracting data bits from the received audio signal, groups of samples representing portions of the received signal are correlated against two frequencies.
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Citations
15 Claims
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1. A Telephone Device for the Deaf (TDD) transitive adapted for TDD signaling and associated with a computer, the TDD transitive comprising:
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a) a sound processor adapted to receive a digital audio signal and generate a transmit audio signal, wherein said sound processor is a sound card adapted to sample an analog signal to generate said digital audio signal and interface with a computing system, said sound card having a first audio input and a first audio output;
b) a correlator provided in the computer and adapted to discriminate between at least two audio tone states found in said digital audio signal and to output a received data stream signal, wherein said correlator discriminates between said at least two audio tone states a number of times per bit time slot, said correlator determining bit values based on a count of said audio tone states discriminated; and
c) a Plain Old Telephone Service (POTS) connector adapted to connect said first audio input and said first audio output to a local loop and to match an impedance of a local loop to an impedance of said first audio input and to an impedance of said first audio output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
a) an audio input connector adapted to receive audio signals;
b) an audio output connector adapted to provide audio signals; and
c) a first switch, the first switch being adapted to connect the audio input connector and the audio output connector to the sound processor via the second audio output and the second audio input, respectively and the switch being further adapted to disconnect the audio input connector and the audio output connector otherwise.
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12. A TDD transitive as claimed in claim 1, wherein the POTS adapter further comprises:
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a) an audio coupler adapted to interface with and convey audio signals to and from a telephone handset; and
b) a second switch, the second switch being adapted to connect the audio coupler to the audio signal conditioning component and the switch being further adapted to disconnect the audio coupler otherwise.
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13. A method for communicating with a Telephone Device for the Deaf (TDD), said method comprising:
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establishing point to point communication between said TDD and a second terminal;
determining according to a protocol a sequence of at least two tones representing an outgoing character data stream;
preparing a digital audio signal using tone data corresponding to said sequence;
transmitting a data stream corresponding to said digital audio signal to said TDD;
receiving an audio signal from said TDD;
providing a digital representation of said received audio signal to a correlator;
correlating said digital signal with at least two audio tone states;
outputting a correlation result signal; and
analyzing said correlation result signal according to a protocol to generate a received data stream. - View Dependent Claims (14, 15)
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Specification