Method of data transmission over telephone circuits and modem therefor

Claim 1

A telephone modem capable of simultaneously transmitting and receiving data signals with less than a given error rate over a common dial-up telephone circuit of a given usable bandwidth, comprising: means converting digital data into analog signals for transmitting said analog signals through said telephone circuit in a first portion of its said usable bandwidth, means receiving analog signals from said telephone circuit for converting those signals within a second portion of said usable bandwidth into digital data, said first and second bandwidth portions each being a different substantially one-half of said telephone circuit bandwidth and arranged to occupy substantially the entire telephone circuit bandwidth, said first and second bandwidth portions overlapping in frequency passband in about the middle of said useable bandwidth and in an amount that local signal echo would normally result in an error rate in excess of said given error rate but remote signal echo would normally result in an error rate less than said given error rate, and means connected between said transmitting and receiving means for subtracting from a received signal any portion of a transmitted signal within the overlapping portion of said first and second bandwidth portions, thereby to suppress the local echo and reduce the error rate from echos to something less than said given rate, whereby utilization of the given telephone circuit bandwidth for rapid data communication is maximized.

Claim 6

A method of simultaneously communicating data signals in two directions between terminals over a common telephone circuit of a given bandwidth, comprising the steps of: confining said data signals in one direction to a first bandwidth portion and said data signals in the other direction to a second bandwidth portion of said telephone circuit bandwidth, said bandwidth portions cummulatively substantially filling said telephone circuit bandwidth and overlapping an amount in about its middle, significantly attenuating at each terminal all frequencies outside of one of said bandwidth portions in an amount wherein signals reflected from the opposite terminal within said one of said bandwidth portions are attenuated to levels that do not excessively interfere with the receipt of a signal within said one of said bandwidth portions, and cancelling from the signal received at each terminal in one of the bandwidth portions any signal transmitted at that terminal that is within said certain range so received, thereby to cancel local echos, whereby the given bandwidth of the telephone circuit is fully utilized, resulting in high speed full duplex data transmission over said telephone circuit.

Claim 7

A method of simultaneously communicating data signals in two directions between terminals over a common telephone circuit of a given bandwidth, comprising the steps of: confining said data signals in one direction to a first bandwidth portion and said data signals in the other direction to a second bandwidth portion of said telephone circuit bandwidth, said bandwidth portions cummulatively substantially filling said telephone circuit bandwidth and overlapping an amount in about its middle, significantly attenuating at each terminal all frequencies outside of one of said bandwidth portions in an amount wherein signals reflected from the opposite terminal within said one of said bandwidth portions are attenuated to levels that do not excessively interfere with the receipt of a signal within said one of said bandwidth portions, and cancelling from the signal received at each terminal in one of the bandwidth portions any signal transmitted at that terminal that is within said certain range so received, thereby to cancel local echos, whereby the given bandwidth of the telephone circuit is fully utilized, resulting in high speed full duplex data transmission over said telephone circuit.

Claim 8

A method of transmitting digital data with less than a given error rate in two directions over a voice dial-up telephone circuit that is of a given bandwidth and includes at least a portion wherein signals travel in both directions over a common circuit, comprising the steps of: converting the digital data originating at one end of the telephone circuit into analog signals within a first pass-band and receiving and decoding into digital data those signals at another end of said telephone circuit, converting the digital data originating at said another end of the telephone circuit into analog signals within a second pass-band and receiving and decoding into digital data those signals at said one end of said telephone circuit, said first and second pass-band portions each being a different substantially one-half of said telephone circuit bandwidth arranged to occupy substantially the entire telephone circuit bandwidth, said first and second bandwidth portions overlapping in frequency passband in about the middle of said usable bandwidth and in an amount that local signals echo would normally result in an error rate in excess of said given error rate but remote signal echo would normally result in an error rate less than said given error rate, . cancelling from the digital signal received at said one end components thereof originating at said one end, thereby to substantially eliminate local echo signals at said one end, and cancelling from the digital signal received at said another end components thereof originating at said another end, thereby to substantially eliminate local echo signals at said another end, whereby utilization of the telephone circuit given bandwidth is maximized for high speed full duplex data transmission.

Claim 9

A method of transmitting digital data with less than a given error rate in two directions over a voice dial-up telephone circuit that is of a given bandwidth and includes at least a portion wherein signals travel in both directions over a common circuit, comprising the steps of: converting the digital data originating at one end of the telephone circuit into analog signals within a first pass-band and receiving and decoding into digital data those signals at another end of said telephone circuit, converting the digital data originating at said another end of the telephone circuit into analog signals within a second pass-band and receiving and decoding into digital data those signals at said one end of said telephone circuit, said first and second pass-band portions each being a different substantially one-half of said telephone circuit bandwidth arranged to occupy substantially the entire telephone circuit bandwidth, said first and second bandwidth portions overlapping in frequency passband in about the middle of said usable bandwidth and in an amount that local signals echo would normally result in an error rate in excess of said given error rate but remote signal echo would normally result in an error rate less than said given error rate, . cancelling from the digital signal received at said one end components thereof originating at said one end, thereby to substantially eliminate local echo signals at said one end, and cancelling from the digital signal received at said another end components thereof originating at said another end, thereby to substantially eliminate local echo signals at said another end, whereby utilization of the telephone circuit given bandwidth is maximized for high speed full duplex data transmission.