US 7,031,394 B2 · Communication systems conveying voice and data signals over standard telephone lines

Abstract

A method for conveying over telephone lines digitized voice signals simultaneously with digital data signals by means of a communication system, having a transmitter having a discrete multi-tone unit yielding a plurality of carriers of different frequency, several of which are assigned to the voice signals and others to the data signals. The carriers for transmitting voice are selected on the basis of their signal-to-noise ratio characteristics, which carriers can be reallocated dynamically to data transmission. A first tone ordering circuit assigns data streams to data carriers, and a second tone ordering circuit assigns voice streams to voice carriers. Each carrier is modulated by QAM modulation, the data carriers by a sequence of QAM symbols representing data and the voice carriers by a sequence of QAM symbols representing voice. QAM modulation is carried out by a first constellation encoder that modulates the data carriers and a second constellation encoder that modulates the voice carriers.

Claims13

Dependent claims

A method for transmitting voice and data signals simultaneously over a telephone subscriber wire pair, the method comprises:

converting at least one voice signal into a corresponding sequence of n-bit digital words in synchronization with a discrete multi-tone (DMT) line signal, where n is an integer;
assigning for voice transmission a portion of a plurality of carriers, each carrier in said portion being characterized by the ability to transmit a number of bits equal to or larger than n per Quadrature Amplitude Modulation (QAM) symbol,
assigning other carriers of the DMT line signal for data transmission;
converting said sequence of n-bit digital words into at least one sequence of n-bit QAM symbols where each QAM symbol has a real component constituted of odd bits of said n-bit digital words and an imaginary component constituted of even bits of said n-bit digital words;
and
sending said at least one sequence of QAM symbols in synchronization with said sequence of n-bit digital words on respective carriers assigned for voice transmission.

3 more elements

A transmitter for a communication system which conveys voice signals and digital data over a telephone subscriber line, the transmitter comprising:

at least one converter connectable to a corresponding external voice signal source for converting said voice signal into at least one sequence of n-bit digital words, where n is an integer;
an assigner connected to each of said converters configured for assigning a portion of carriers of discrete multi-tone (DMT) signal for voice transmission;
a constellation encoder configured for receiving said at least one sequence of n-bit digital words and being configured for modulating said portion of said carriers with at least one sequence of n-bit Quadrature Amplitude Modulation (QAM) symbols that correspond to said at least one sequence of n-bit digital words, where each QAM symbol has a real component constituted of odd bits of said n-bit digital words and an imaginary component constituted of even bits of said n-bit digital words;
a synchronizer connected at least to said at least one converter and configured for effecting synchronization between frames of said DMT signal and said sequence of said n-bit digital words;
and
a loader configured for conveying said at least one sequence of QAM symbols in synchronization with said sequence of n-bit digital words on respective carriers assigned for voice transmission.

3 more elements

Dependencies are inferred from the claim text.

Communication systems conveying voice and data signals over standard telephone lines

Life of this patent

Communication systems conveying voice and data signals over standard telephone lines

Life of this patent

Abstract

Claims13