High-speed analog modem

• US 20040095257A1
• Filed: 08/11/2003
• Published: 05/20/2004
• Est. Priority Date: 08/12/2002
• Status: Abandoned Application

• Current Assignee: Smartlink Limited
• Original Assignee: Smartlink Limited
• Inventors: Maytal, Benjamin, Koifman, Gil, Tal, Tsahi
• Application Number:
  US10/639,198
• Publication Number:
  US 20040095257A1
• Time in Patent Office: Days
• US Class Current: 340/870.21
• CPC Class Codes: H04L 25/4927 using levels matched to the quantisation levels of the channel
• CPC Class Codes: H04L 5/06 the signals being represented by different frequencies combined with time-division multiplexing H04L5/26
• CPC Class Codes: H04L 5/1446 of transmission speed

Abstract

Apparatus for data communication includes a transmitter, which is adapted to generate a sequence of symbols at a variable symbol rate, responsively to a stream of digital data, and to convert the sequence to an analog data signal for transmission over a communication medium. A receiver includes an analog/digital converter (ADC), which is adapted to receive and digitize the data signal at a variable sampling rate so as to generate a sequence of digital samples, and digital processing circuitry, which is coupled to process the digital samples so as to extract the stream of digital data therefrom. The transmitter and the receiver are adapted to negotiate over the communication medium so as to set the sampling rate of the ADC and to determine the symbol rate responsively to the sampling rate.

Claims

1. A data receiver, comprising:

an analog front end circuit, which is adapted to receive a data signal from a transmitter over a communication medium;

an analog/digital converter (ADC), which is coupled to digitize the data signal at a variable sampling rate so as to generate a sequence of digital samples; and

digital processing circuitry, which is coupled to process the digital samples so as to extract a stream of digital data therefrom, and which is adapted to negotiate with the transmitter over the communication medium so as to set the sampling rate of the ADC and to determine a variable symbol rate of the data signal responsively to the sampling rate.

2. The receiver according to claim 1, wherein the communication medium comprises a telephone line, and wherein the digital processing circuitry is adapted to process the digital samples substantially in accordance with a communication scheme provided by a voice-band modem specification and to set the sampling rate to be greater than 10 kHz.

3. The receiver according to claim 1, wherein the communication medium comprises a telephone line, and wherein the digital processing circuitry is adapted to process the digital samples substantially in accordance with a communication scheme provided by a voice-band modem specification and to negotiate with the transmitter so as to set the variable symbol rate to be substantially in excess of 8000 symbols/sec.

4. The receiver according to claim 3, wherein the voice-band modem specification is selected from among ITU-T recommendations V.34, V.90 and V.92.

5. The receiver according to claim 1, wherein the communication medium comprises a telephone line, and wherein the digital processing circuitry is adapted to process the digital samples substantially in accordance with a communication scheme provided by a voice-band modem specification and to negotiate with the transmitter so as to set a variable data rate of the data signal to be in excess of 60 kbps.

6. The receiver according to claim 1, wherein the digital processing circuitry has computing resources and is adapted to determine a level of availability of the resources for processing the digital samples, and wherein the digital processing circuitry is further adapted to negotiate with the transmitter over the communication medium so as to set the variable symbol rate responsively to the level of availability of the resources.

7. A data transmitter, comprising:

data modulation circuitry, which is coupled to receive a stream of digital input data and to encode the input data substantially in accordance with a communication scheme provided by a voice-band modem specification, so as to generate an output sequence of data symbols at a symbol rate substantially in excess of 8000 symbols/sec;

a digital/analog converter (DAC), which is coupled to convert the sequence of data symbols into an analog data signal; and

an analog front end circuit, which is coupled to transmit the analog data signal over a telephone line.

8. The transmitter according to claim 7, wherein the data modulation circuitry is adapted to generate the output sequence of data symbols so that the data signal has a data rate substantially in excess of 60 kbps.

9. The transmitter according to claim 7, wherein the voice-band modem specification is selected from among ITU-T recommendations V.34, V.90 and V.92.

10. The transmitter according to claim 9, wherein the voice-band modem specification comprises one of the V.90 and V.92 recommendations, and wherein the data modulation circuitry is adapted to generate the output sequence of data symbols using a substantially linear constellation.

11. The transmitter according to claim 9, wherein the voice-band modem specification comprises one of the V.90 and V.92 recommendations, and wherein the data modulation circuitry is adapted to generate the output sequence of data symbols using a constellation that is not a subset of pulse code modulation (PCM) constellation levels defined in a G.711 standard.

12. The transmitter according to claim 9, wherein the data modulation circuitry is adapted to generate the output sequence of data symbols using a pulse amplitude modulation scheme allowing a constellation size of more than 256 levels.

13. The transmitter according to claim 7, wherein the DAC generates the analog data signal at a variable sample rate, and wherein the data modulation circuitry is adapted to negotiate over the telephone line with a receiver of the analog data signal so as to determine the sample rate, responsively to a condition of the telephone line.

14. The transmitter according to claim 13, wherein the data modulation circuitry is further adapted to apply a pre-emphasis to the data symbols, responsively to a filter characteristic selected by the receiver.

15. The transmitter according to claim 13, wherein the data modulation circuitry is adapted to determine the symbol rate further responsively to a level of availability of a communication resource of at least one of the transmitter and the receiver.

16. Apparatus for data communication, comprising:

an analog front end circuit, which is adapted to receive an incoming data signal transmitted over a communication medium by a transmitter at a variable data transmission rate;

an analog/digital converter (ADC), which is coupled to digitize the incoming data signal so as to generate a sequence of digital samples; and

a computer, which has computing resources and is programmed by software instructions to process the digital samples using the computing resources so as to extract an input stream of digital data therefrom, and which is further programmed to determine a level of availability of the computing resources and to negotiate with the transmitter over the communication medium so as to determine the data transmission rate responsively to the level of availability of the resources.

17. The apparatus according to claim 16, wherein the computer comprises a central processing unit (CPU), and wherein the computing resources comprise a processing power of the CPU.

18. The apparatus according to claim 16, wherein the computing resources comprise a memory.

19. The apparatus according to claim 16, wherein the computer is further programmed to generate digital symbols for output over the communication medium at a variable symbol rate responsively to an output stream of digital data, and to determine the symbol rate responsively to the level of availability of the resource.

20. The apparatus according to claim 16, wherein the data transmission rate is determined further responsively to a system resource constraint of the transmitter.

21. Apparatus for data communication, comprising:

a transmitter, which is adapted to generate a sequence of symbols at a variable symbol rate, responsively to a stream of digital data, and to convert the sequence to an analog data signal for transmission over a communication medium; and

a receiver, which comprises;

an analog/digital converter (ADC), which is adapted to receive and digitize the data signal at a variable sampling rate so as to generate a sequence of digital samples; and

digital processing circuitry, which is coupled to process the digital samples so as to extract the stream of digital data therefrom,

wherein the transmitter and the receiver are adapted to negotiate over the communication medium so as to set the sampling rate of the ADC and to determine the symbol rate responsively to the sampling rate.

22. The apparatus according to claim 21, wherein the communication medium comprises a telephone line, and wherein the transmitter is adapted to generate the sequence of symbols substantially in accordance with a communication scheme provided by a voice-band modem specification, and wherein the receiver is adapted to set the sampling rate to be greater than 10 kHz.

23. The apparatus according to claim 21, wherein the communication medium comprises a telephone line, and wherein the transmitter is adapted to generate the sequence of symbols substantially in accordance with a communication scheme provided by a voice-band modem specification, while setting the variable symbol rate to be substantially in excess of 8000 symbols/sec.

24. The apparatus according to claim 23, wherein the voice-band modem specification is selected from among ITU-T recommendations V.34, V.90 and V.92.

25. The apparatus according to claim 21, wherein the communication medium comprises a telephone line, and wherein the transmitter is adapted to generate the sequence of symbols substantially in accordance with a communication scheme provided by a voice-band modem specification, so that the analog data signal has a data rate in excess of 60 kbps.

26. The apparatus according to claim 21, wherein the receiver has computing resources and is adapted to determine a level of availability of the resources for processing the digital samples, and wherein the receiver is further adapted to negotiate with the transmitter over the communication medium so as to set the variable symbol rate responsively to the level of availability of the resources.

27. Apparatus for data communication, comprising:

a transmitter, which comprises;

data modulation circuitry, which is coupled to receive a stream of digital input data and to encode the input data substantially in accordance with a communication scheme provided by a voice-band modem specification, so as to generate an output sequence of data symbols at a symbol rate substantially in excess of 8000 symbols/sec;

a digital/analog converter (DAC), which is coupled to convert the sequence of data symbols into an analog data signal; and

an analog front end circuit, which is coupled to transmit the analog data signal over a telephone line; and

a receiver, which is adapted to receive the analog data signal over the telephone and to process the analog signal so as to extract the digital input data therefrom.

28. The apparatus according to claim 27, wherein the data modulation circuitry is adapted to generate the output sequence of data symbols so that the data signal has a data rate substantially in excess of 60 kbps.

29. The apparatus according to claim 27, wherein the voice-band modem specification is selected from among ITU-T recommendations V.34, V.90 and V.92.

30. The apparatus according to claim 29, wherein the voice-band modem specification comprises one of the V.90 and V.92 recommendations, and wherein the data modulation circuitry is adapted to generate the output sequence of data symbols using a substantially linear constellation.

31. The apparatus according to claim 29, wherein the voice-band modem specification comprises one of the V.90 and V.92 recommendations, and wherein the data modulation circuitry is adapted to generate the output sequence of data symbols using a constellation that is not a subset of pulse code modulation (PCM) constellation levels defined in a G.711 standard.

32. The apparatus according to claim 29, wherein the data modulation circuitry is adapted to generate the output sequence of data symbols using a pulse amplitude modulation scheme allowing a constellation size of more than 256 levels.

33. The apparatus according to claim 27, wherein the DAC generates the analog data signal at a variable sample rate, and wherein the transmitter and receiver are adapted to negotiate over the telephone line so as to determine the sample rate, responsively to a condition of the telephone line.

34. The apparatus according to claim 33, wherein the data modulation circuitry is adapted to apply a pre-emphasis to the data symbols, responsively to a filter characteristic selected by the receiver.

35. The apparatus according to claim 33, wherein the transmitter and receiver are adapted to determine the symbol rate further responsively to a level of availability of a communication resource of at least one of the transmitter and the receiver.

36. Apparatus for data communication, comprising:

a transmitter, which is adapted to generate an analog data signal, responsively to an input stream of digital data, at a variable data transmission rate for transmission over a communication medium; and

a receiver, which comprises;

an analog/digital converter (ADC), which is adapted to receive and digitize the analog data signal so as to generate a sequence of digital samples; and

a computer, which has computing resources and is programmed by software instructions to process the digital samples using the computing resources so as to extract the input stream of digital data therefrom, and which is further programmed to determine a level of availability of the computing resources and to negotiate with the transmitter over the communication medium so as to determine the data transmission rate responsively to the level of availability of the resources.

37. The apparatus according to claim 36, wherein the computer comprises a central processing unit (CPU), and wherein the computing resources comprise a processing power of the CPU.

38. The apparatus according to claim 36, wherein the computing resources comprise a memory.

39. The apparatus according to claim 36, wherein the computer is further programmed to generate digital symbols for output over the communication medium at a variable symbol rate responsively to an output stream of digital data, and to determine the symbol rate responsively to the level of availability of the resource.

40. The apparatus according to claim 36, wherein the data transmission rate is determined further responsively to a system resource constraint of the transmitter.

41. A method for communication, comprising:

negotiating with a transmitter over a communication medium so as to determine a variable sampling rate of a data signal to be transmitted by the transmitter and to set a variable symbol rate of the data signal responsively to the determined sampling rate receiving the data signal from the transmitter over the communication medium;

digitizing the received data signal at the determined sampling rate so as to generate a sequence of digital samples; and

processing the digital samples so as to extract a stream of digital data therefrom.

42. The method according to claim 41, wherein the communication medium comprises a telephone line, and wherein negotiating with the transmitter comprises setting the variable sampling rate to be greater than 10 kHz, and

wherein processing the digital samples comprises decoding the samples substantially in accordance with a communication scheme provided by a voice-band modem specification.

43. The method according to claim 41, wherein the communication medium comprises a telephone line, and wherein negotiating with the transmitter comprises setting the variable symbol rate to be substantially in excess of 8000 symbols/sec, and

wherein processing the digital samples comprises decoding the samples substantially in accordance with a communication scheme provided by a voice-band modem specification.

44. The method according to claim 43, wherein the voice-band modem specification is selected from among ITU-T recommendations V.34, V.90 and V.92.

45. The method according to claim 41, wherein the communication medium comprises a telephone line, and wherein negotiating with the transmitter comprises setting a variable data rate of the data signal to be in excess of 60 kbps, and

wherein processing the digital samples comprises decoding the samples substantially in accordance with a communication scheme provided by a voice-band modem specification.

46. The method according to claim 41, wherein negotiating with the transmitter comprises determining a level of availability of resources for processing the digital samples, and setting the variable symbol rate responsively to the level of availability of the resources.

47. A method for communication, comprising:

encoding a stream of digital input data substantially in accordance with a communication scheme provided by a voice-band modem specification, so as to generate an output sequence of data symbols at a symbol rate substantially in excess of 8000 symbols/sec;

converting the sequence of data symbols into an analog data signal; and

transmitting the analog data signal over a telephone line.

48. The method according to claim 47, wherein encoding the stream of digital input data comprises generating the output sequence of data symbols at a data rate substantially in excess of 60 kbps.

49. The method according to claim 47, wherein the voice-band modem specification is selected from among ITU-T recommendations V.34, V.90 and V.92.

50. The method according to claim 49, wherein the voice-band modem specification comprises one of the V.90 and V.92 recommendations, and wherein encoding the stream of digital input data comprises generating the output sequence of data symbols using a substantially linear constellation.

51. The method according to claim 49, wherein the voice-band modem specification comprises one of the V.90 and V.92 recommendations, and wherein encoding the stream of digital input data comprises generating the output sequence of data symbols using a constellation that is not a subset of pulse code modulation (PCM) constellation levels defined in a G.711 standard.

52. The method according to claim 49, wherein encoding the stream of digital input data comprises generating the output sequence of data symbols using a pulse amplitude modulation scheme allowing a constellation size of more than 256 levels.

53. The method according to claim 47, and comprising negotiating over the telephone line with a receiver of the analog data signal so as to determine a sample rate for converting the sequence of data symbols into the analog data signal, responsively to a condition of the telephone line.

54. The method according to claim 53, wherein encoding the stream of digital input data comprises applying a pre-emphasis to the data symbols, responsively to a filter characteristic selected by the receiver.

55. The method according to claim 53, wherein negotiating with the receiver comprises determining the symbol rate further responsively to a level of availability of a communication resource used in the communication.

56. A method for data communication, comprising:

determining a level of availability of computing resources of a computer, which is programmed in software to receive and process an incoming data signal from a transmitter;

negotiating with the transmitter over a communication medium so as to determine a variable data transmission rate of the incoming data signal responsively to the level of availability of the resources;

receiving and digitizing the incoming data signal transmitted over a communication medium by the transmitter at the determined data transmission rate, so as to generate a sequence of digital samples; and

processing the digital sample using the computing resources of a computer, so as to extract an input stream of digital data therefrom.

57. The method according to claim 56, wherein the computer comprises a central processing unit (CPU), and wherein the computing resources comprise a processing power of the CPU.

58. The method according to claim 56, wherein the computing resources comprise a memory of the computer.

59. The method according to claim 56, and comprising determining, responsively to the level of availability of the resource, a symbol rate of an outgoing data signal to by generated by the computer using the computing resources, and generating the outgoing data signal for output over the communication medium at the determined symbol rate responsively to an output stream of digital data.

60. The method according to claim 56, wherein negotiating with the transmitter comprises determining the data transmission rate further responsively to a system resource constraint of the transmitter.

61. A computer software product, comprising a computer-readable medium in which program instructions are stored, which instructions, when read by a computer, cause the computer to accept as input a sequence of digital samples generated responsively to a data signal received from a transmitter over a communication medium and digitized at a variable sampling rate, and cause the computer to process the digital samples so as to extract a stream of digital data therefrom,

wherein the instructions further cause the computer to negotiate with the transmitter over the communication medium so as to set the variable sampling rate and to determine a variable symbol rate of the data signal responsively to the sampling rate.

62. The product according to claim 61, wherein the communication medium comprises a telephone line, and wherein the instructions cause the computer to process the digital samples substantially in accordance with a communication scheme provided by a voice-band modem specification and to negotiate with the transmitter so as to set the variable sampling rate to be greater than 10 kHz.

63. The product according to claim 61, wherein the communication medium comprises a telephone line, and wherein the instructions cause the computer to process the digital samples substantially in accordance with a communication scheme provided by a voice-band modem specification and to negotiate with the transmitter so as to set the variable symbol rate to be substantially in excess of 8000 symbols/sec.

64. The product according to claim 63, wherein the voice-band modem specification is selected from among ITU-T recommendations V.34, V.90 and V.92.

65. The product according to claim 61, wherein the communication medium comprises a telephone line, and wherein the instructions cause the computer to process the digital samples substantially in accordance with a communication scheme provided by a voice-band modem specification and to negotiate with the transmitter so as to set a data rate of the data signal to be in excess of 60 kbps.

66. The product according to claim 61, wherein the computer has computing resources, and wherein the instructions cause the computer to determine a level of availability of the resources for processing the digital samples, and to negotiate with the transmitter over the communication medium so as to set the variable symbol rate responsively to the level of availability of the resources.

67. A computer software product, comprising a computer-readable medium in which program instructions are stored, which instructions, when read by a computer having computing resources, cause the computer to accept as input a sequence of digital samples generated responsively to an incoming data signal transmitted over a communication medium by a transmitter at a variable data transmission rate, and to process the digital samples using the computing resources so as to extract an input stream of digital data therefrom,

wherein the instructions further cause the computer to determine a level of availability of the computing resources and to negotiate with the transmitter over the communication medium so as to determine the data transmission rate responsively to the level of availability of the resources.

68. The product according to claim 67, wherein the computer comprises a central processing unit (CPU), and wherein the computing resources comprise a processing power of the CPU.

69. The product according to claim 67, wherein the computing resources comprise a memory of the computer.

70. The product according to claim 67, wherein the instructions further cause the computer to generate digital symbols for output over the communication medium at a variable symbol rate responsively to an output stream of digital data, and to determine the symbol rate responsively to the level of availability of the resource.

71. The product according to claim 67, wherein the instructions cause the computer to determine the data transmission rate further responsively to a system resource constraint of the transmitter.

72. A data transmitter, comprising:

data modulation circuitry, which is coupled to receive a stream of digital input data and to process the input data so as to generate an output sequence of data samples at a variable sample rate, and which is adapted to negotiate with a receiver over a communication medium so as to set the sample rate and to determine, responsively to the sample rate, a variable symbol rate of an analog data signal to be transmitted by the transmitter;

a digital/analog converter (DAC), which is coupled to convert the sequence of data samples into the analog data signal at the sample rate set by negotiation with the receiver; and

an analog front end circuit, which is coupled to transmit the analog data signal over the communication medium to the receiver.

73. A data receiver, comprising:

an analog front end circuit, which is adapted to receive a data signal from a transmitter over a communication medium;

an analog/digital converter (ADC), which is coupled to digitize the data signal at a fixed sampling rate so as to generate a sequence of digital samples; and

digital processing circuitry, which is coupled to process the digital samples so as to extract a stream of digital data therefrom, and which is adapted to negotiate with the transmitter over the communication medium so as to set a variable sample rate of the data signal and to determine a variable symbol rate of the data signal responsively to the sample rate, the digital processing circuitry comprising a rate converter, which is adapted to covert the sequence of samples at the fixed sampling rate to the variable sample rate prior to extraction of the digital data therefrom.

74. A data transmitter, comprising:

data modulation circuitry, which is coupled to receive a stream of digital input data and to process the input data so as to generate an output sequence of data samples at a variable sample rate, and which is adapted to negotiate with a receiver over a communication medium so as to set the sample rate and to determine, responsively to the sample rate, a variable symbol rate of an analog data signal to be transmitted by the transmitter, the data modulation circuitry comprising a rate converter, which is adapted to convert the output sequence of data samples to a predetermined, fixed sample rate;

a digital/analog converter (DAC), which is coupled to convert the output sequence of data samples into the analog data signal at the fixed sample rate; and

an analog front end circuit, which is coupled to transmit the analog data signal over the communication medium to the receiver.