Method and apparatus for transmitting digital data and real-time digitalized voice information over a communications channel
First Claim
1. A method of transmitting digitalized voice and data over a communications channel as a combined data stream, said digitalized voice being formed by digitalizing a voice signal using an encoding protocol wherein various amplitude levels of said voice signal are each represented as an individual bit code, at least a first amplitude level being represented by at least first and second redundant said bit codes, said digitalized voice being transmitted over said communications channel in substantially real time, comprising:
- substituting said second redundant bit code for said first redundant bit code when said first redundant code is detected in said digitalized voice;
monitoring said voice signal to detect the absence of any substantial voice communication;
inserting said first redundant code in said data stream to signal the beginning of data transmission when no substantial voice communication is detected by said step of monitoring;
inserting data into said combined data stream for a period of time after said first redundant code; and
transmitting said data stream including said digitalized data over said communications channel.
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Abstract
A system and method transmits digitalized voice and data over a communications channel as a combined data stream while transmitting the digitalized voice in substantially real-time. The system makes use of a redundancy in the coding used to represent at least one amplitude level in the digitalized voice by using one of the redundant codings as a signalling code in a signalling time frame to signal the presence of data and by converting a digitalized voice codeword having this redundant code to its duplicate code. In this manner, during silence periods of the voice communication on the communications channel, data may be inserted. The system and method allow digital data to be transmitted without any limitation on its bit density. As the communications channel normally has a bit density requirement requiring at least a certain density of digital ones, the system of the present invention monitors the digitalized data to determine when the number of consecutive zeros exceeds a predetermined number and inserts a one into the data stream to insure that bit density requirements are not violated. The receiver tests for the signalling code indicative of the presence of data and based on this code, transmits the data and voice to their respective proper locations at the downstream end of the communications channel. Later, the receiver removes any inserted ones from the digital data stream to recover the digital data.
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Citations
13 Claims
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1. A method of transmitting digitalized voice and data over a communications channel as a combined data stream, said digitalized voice being formed by digitalizing a voice signal using an encoding protocol wherein various amplitude levels of said voice signal are each represented as an individual bit code, at least a first amplitude level being represented by at least first and second redundant said bit codes, said digitalized voice being transmitted over said communications channel in substantially real time, comprising:
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substituting said second redundant bit code for said first redundant bit code when said first redundant code is detected in said digitalized voice; monitoring said voice signal to detect the absence of any substantial voice communication; inserting said first redundant code in said data stream to signal the beginning of data transmission when no substantial voice communication is detected by said step of monitoring; inserting data into said combined data stream for a period of time after said first redundant code; and transmitting said data stream including said digitalized data over said communications channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of transmitting data during idle intervals of voice conversation transmitted over a communication channel in real time comprising:
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transmitting said voice conversation with interleaved data by, developing a plurality of pulse code modulated voice codewords which encode said voice conversation, assembling said voice codewords into code groups, each code group including a predetermined number of said codewords, monitoring voice activity of said voice conversation by monitoring said voice codewords of a said code group to identify idle frames containing voice codewords which encode said conversation but have no significant voice activity, p2 replacing, upon detection of an idle frame, the first voice codeword of a next succeeding code group which encodes said conversation with a data transfer codeword, said data transfer codeword being different from any said voice codeword, replacing, upon detection of an idle frame, the second and subsequent voice code words of the next succeeding code group with data codewords representing data to be transmitted; transmitting said code groups on said communication channel; and receiving said voice conversation with interleaved data and removing said data therefrom by, monitoring each said code groups received from said communication channel, examining the first said codeword of each said code group to determine if the first said codeword of each said transmitted code group is a data transfer codeword;
to identify the remaining codewords of said code group as data codewords,converting all said codewords within said code group to an analog voice signal to complete transmission of said voice conversation when said first codeword is not a said data transfer codeword, and supplying the second and subsequent codewords within said code group, when said first codeword is a data transfer codeword, as a digital data string.
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10. A system of transmitting digitalized voice and data over a communications channel as a combined data stream, said digitalized voice being formed by digitalizing a voice signal using an encoding protocol wherein various amplitude levels of said voice signal are each represented as an individual bit code, at least a first amplitude level being represented by at least first and second redundant bit codes, comprising:
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first input means for providing said digitalized voice signal; second input means for providing said data; voice activity monitor means, responsive to said first input means, for detecting idle periods in said digitalized voice signal and for producing an idle output representative thereof; signalling generator means, operatively connected to said first input means, for substituting, during at least an initial periodic time frame, said second redundant code for said first redundant code in said digitalized voice signal, and for developing said first redundant code as a data start signalling code when data is to be transmitted; switch means, operatively connected between said communications channel and said signalling generator means, first input means and second input means, for supplying one of said digitalized voice signal, said data or said data start signalling code to said communications channel; and control means, responsive to the output of said voice activity monitor means, for controlling said switch means, said control means connecting said switch means to said first input means to transmit said digitalized voice signal, and connecting said switch means to said second input to supply data to said communications channel, said control means further controlling said signalling generator means and connecting said switch means to said signalling generator means during said periodic time frame; said control means reconnecting said switch means to said first input means when an idle period is no longer detected in said digitalized voice. - View Dependent Claims (12)
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11. The system of claim 11 wherein said individual bit codes associated with a single voice channel are arranged into a code group, the first individual bit code of each code group occurring during said initial periodic time frame while other individual bit codes of a said code group occur during other periodic time frames,
said control means connecting said switch means to said signalling generator means during said initial periodic time frame, said control means controlling said signalling generator means to generate said data start signalling code in response to the detection of an idle signal by said voice activity monitor means, said control means connecting said switch means to said first input means or said second input means depending on whether an idle period is detected by said voice activity monitor means during the remaining periodic time frames of each said code group.
Specification