Digital data over voice communication

• US 5,025,443 A
• Filed: 04/28/1989
• Issued: 06/18/1991
• Est. Priority Date: 02/24/1988
• Status: Expired due to Fees

• Current Assignee: Integrated Network Corp.
• Original Assignee: Integrated Network Corp.
• Inventors: Gupta, Dev V.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Chin, Wellington
• Application Number:
  US07/345,472
• Time in Patent Office: 781 Days
• Field of Search: 370/69.1, 370/76, 375/17, 375/18, 375/61
• US Class Current: 370/494
• CPC Class Codes: H04L 25/4925 using balanced bipolar ternary codes
• CPC Class Codes: H04M 11/062 using different frequency bands for speech and other data

Abstract

A method and apparatus is described for transmitting and receiving data signals and voice band signals over a single pair of wires, wherein the energy content of the data signals in the voice band is transferred to a higher frequency to avoid interference between the two. This is accomplished by sinusoidally encoding the data pulses in the frequency domain. The encoding is equivalently performed in the time domain by linearly combining weighted delayed and advanced versions of the data pulses, in accordance with a weighting formula. A transversal filter is used to multiple delayed and advanced versions of the data pulses by a scaling factor times the ratio of m!/m-i)!i! factorial wherein i is the ith version being weighted, m is an integer greater than one and ! indicates the factorial function.

Claims

1. Apparatus for encoding data signals for transmission at a predetermined rate over telephone lines in the presence of voice band telephone signals such that the frequency spectrum of the data signals is substantially removed from the voice band and is shifted to a higher frequency spectrum comprising:

(a) generator means for generating pulsed data signals in bit intervals of duration T;

(b) coding means for forming linear combinations of said pulsed data signals with delayed and advanced version thereof to sinusoidally encode the pulses in the frequency domain by converting each data bit into a corresponding data symbol having a duration 5T/2, the data symbol being composed of five pulses spaced T/2 apart having alternately opposite polarities and equal durations of not more than T/2, the amplitudes of a first pair of pulses on either side of a central pulse being equal and being "a" times an amplitude of the central pulse, where "a" is a factor ≦

1, and the amplitudes of a second pair of pulses on either side of the first pair of pulses being equal and being "b" times the amplitude of the central pulse where "b" is a factor ≦

1.

2. The apparatus of claim 1 wherein the data signals are in the form of substantially Nyquist pulses.

3. A transmission system comprising:

(a) a transmitter for transmitting binary data signals via a transmission means, the transmitter comprising;

(i) a data source for generating data bits in synchronous consecutive bit intervals having a duration T; and

(ii) a code converter for converting each data bit into a corresponding data symbol; and

(b) a receiver comprising;

(i) a receiver filter; and

(ii) a data detector for detecting the transmitted data symbols;

wherein the improvement comprises that;

(c) the code-converter is arranged to convert each data it into a corresponding data symbol having a duration 5T/2, the data symbol being composed of five pulses of T/2 duration having alternately opposed polarities, the amplitudes of a first pair of pulses on either side of a central pulse being equal and being "a" times an amplitude of the central pulse, where "a" is a factor≦

1, and amplitudes of a second pair of pulses on either side of the first pair of pulses being equal and being "b" times the amplitude of the central pulse where "b" is a factor≦

1.

5. A transmission system as claimed in claim 3 wherein "a " is 0.6667 and "b" is 0.1667.

4. A transmission system comprising:

(a) a transmitter for transmitting binary data signals via a high-pass transmission means, the transmitter comprising;

(i) a data source for generating data bits in synchronous consecutive bit intervals having a duration T; and

(ii) a code converter for converting each data bit into a corresponding data symbol of duration 5T/2, the data symbol being composed of first, second, third, fourth, and fifth pulses, each pulse being of equal pulse duration, said pulse duration being not more than T/2, said pulses being equally spaced, and said pulses being of alternately opposite polarities, said third pulse being a central pulse having an amplitude, said second and fourth pulses forming a first pair of pulses on either side of the central pulse, said first pair of pulses having equal amplitudes which are a factor of "a" times the amplitude of the central pulse, where "a" is a number less than or equal to one, the first and fifth pulses forming a second pair of pulses on either side of the first pair of pulses, the second pair of pulses having equal amplitudes which are a factor of "b" times the amplitude of the central pulse, where "b" is a number less than or equal to one, whereby transmitted data symbols overlap to form a multi-level transmission signal; and

(b) a receiver comprising;

(i) a receive filter; and

(ii) a data detector for detecting the transmitted data symbols.

6. A code converter comprising:

(a) an input for receiving data bits in synchronous consecutive bit intervals of duration T;

(b) means for converting each data bit into a corresponding data symbol of duration 5T/2, the data symbol being composed of first, second, third, fourth, and fifth pulses, each pulse being of equal pulse duration, said pulse duration being not more than T/2, said pulses being equally spaced, and of alternately opposite polarities, said third pulse being a central pulse having an amplitude, said second and fourth pulses forming a first pair of pulses on either side of the central pulse, said first pair of pulses having equal amplitudes which are a factor of "a" times the amplitude of the central pulse, where "a" is a number less than or equal to one, the first and fifth pulses forming a second pair of pulses on either side of the first pair of pulses, the second pair of pulses having equal amplitudes which are a factor of "b" times the amplitude of the central pulse, where "b" is a number less than or equal to one;

(c) an output at which said data symbol is provided.

7. The converter of claim 6 wherein "a" is 0.6667 and "b" is 0.1667.

8. A receiver for receiving data symbols representing binary data signals, including data bits having consecutive bit intervals of duration T, the receiver comprising:

(a) an input for receiving data symbols which are composed of first, second, third, fourth, and fifth pulses, each pulse being of equal pulse duration, said pulse duration being not more than T/2, said pulses being equally spaced, so that sequential pulses are 5T/2 apart, and said pulses being of alternately opposite polarities, said third pulse being a central pulse having an amplitude, said second and fourth pulses forming a first pair of pulses on either side of the central pulse, said first pair of pulses having equal amplitudes which are a factor of "a" times the amplitude of the central pulse, where "a" is a number less than or equal to one, the first and fifth pulses forming a second pair of pulses on either side of the first pair of pulses, the second pair of pulses having equal amplitudes which are a factor of "b" times the amplitude of the central pulse, where "b" is a number less than or equal to one;

(b) a receive filter coupled to the input; and

(c) a data detector coupled to an output of the receive filter for detecting the data symbols.

9. A transmitter for transmitting binary data signals, the transmitter comprising:

(a) a data source for generating data bits in synchronous consecutive bit intervals having a duration T;

(b) a code converter for converting each data bit into a corresponding data symbol of duration 5T/2, the data symbol being composed of first, second, third, fourth, and fifth pulses, each pulse being of equal pulse duration, said pulse duration being not more than T/2, said pulses being equally spaced, so that sequential pulses are 5T/2 apart, and said pulses being of alternately opposite polarities, said third pulse being a central pulse having an amplitude, said second and fourth pulses forming a first pair of pulses on either side of the central pulse, said first pair of pulses having equal amplitudes which are a factor of "a" times the amplitude of the central pulse, where "a" is a number less than or equal to one, the first and fifth pulses forming a second pair of pulses on either side of the first pair of pulses, the second pair of pulses having equal amplitudes which are a factor of "b" times the amplitude of the central pulse, where "b" is a number less than or equal to one.

10. The transmitter of claim 9 wherein "a" is 0.6667 and "b" is 0.1667.