Technique for improving the quality of digital signals in a multi-level signaling system
A technique for improving the quality of digital signals in a multi-level signaling system is disclosed. In one particular exemplary embodiment, the technique may be realized as a method for improving the quality of transmitted digital signals in a multi-level signaling system wherein digital signals representing more than one bit of information may be transmitted at more than two signal levels on a single transmission medium. The method may comprise encoding digital values represented by sets of N bits to provide corresponding sets of P symbols, wherein each set of P symbols is formed to reduce full-swing transitions between successive digital signal transmissions.
1. A method for improving the quality of transmitted digital signals in a multi-level signaling system wherein digital signals representing more than one bit of information may be transmitted at more than two signal levels on a single transmission medium, the method comprising the step of:
encoding digital values represented by sets of N bits to provide corresponding sets of P symbols, each set of P symbols being formed to reduce full-swing transitions between successive digital signal transmissions.
2. The method as defined in claim 1 , wherein each set of P symbols is formed with Q bits, wherein Q is greater than N.
3. The method as defined in claim 2 , wherein N=8 and Q=10.
4. The method as defined in claim 2 , wherein N=10 and Q=12.
5. The method as defined in claim 2 , wherein N=16 and Q=20.
6. The method as defined in claim 2 , wherein N=9 and Q=10.
7. The method as defined in claim 2 , wherein N=25 and Q=26.
8. The method as defined in claim 1 , wherein digital signals may be transmitted at four signal levels on a single transmission medium.
9. The method as defined in claim 1 , wherein digital signals may be transmitted at five signal levels on a single transmission medium.
10. The method as defined in claim 1 , wherein the single transmission medium comprises a single electrical conductor.
11. The method as defined in claim 1 , wherein the single transmission medium comprises a differential pair of electrical conductors.
12. The method as defined in claim 1 , wherein the single transmission medium comprises an optical fiber.
13. The method as defined in claim 1 , wherein each symbol represents two bits.
14. The method as defined in claim 1 , wherein each set of P symbols includes at least one transition that is substantially geometrically centered.
15. The method as defined in claim 1 , wherein a particular symbol in each set of P symbols is formed to ensure that undesirable transitions do not occur between neighboring sets of P symbols.
16. The method as defined in claim 1 , wherein the step of encoding comprises adding at least one bit having a fixed bit value to the N bits to generate each set of P symbols.
17. The method as defined in claim 1 , wherein the step of encoding comprises the steps of:
adding a parity bit to the N bits; and
substituting at least one bit having a fixed bit value for at least one of the N bits to generate each set of P symbols.
18. The method as defined in claim 1 , wherein the step of encoding comprises the step of:
forming pairs of symbols in each set of P symbols based upon the value of corresponding pairs of bits in the N bits.
19. The method as defined in claim 1 , further comprising the steps of:
transmitting the sets of P symbols;
receiving the transmitted sets of P symbols; and
decoding the digital values represented by the sets of N bits from the transmitted sets of P symbols.
20. The method as defined in claim 1 , wherein each set of P symbols is formed to eliminate full-swing transitions between at least every other successive digital signal transmission.
21. The method as defined in claim 1 , wherein each set of P symbols is formed to eliminate non-full-swing transitions between at least every other successive digital signal transmission.
22. A method for improving the quality of transmitted digital signals in a multi-level signaling system wherein digital signals representing more than one bit of information may be transmitted at more than two signal levels on a single transmission medium, the method comprising the step of:
encoding digital values represented by sets of N bits to provide corresponding sets of P symbols, each set of P symbols being formed to reduce non-full-swing transitions between successive digital signal transmissions.
23. The method as defined in claim 22 , wherein each set of P symbols is also formed to eliminate full-swing transitions between successive digital signal transmissions.
24. The method as defined in claim 22 , wherein the step of encoding comprises the step of:
forming each symbol in each set of P symbols based upon the value of a corresponding pair of bits in the N bits.
25. The method as defined in claim 24 , wherein the step of encoding further comprises the step of:
forming each symbol in each set of P symbols based upon the value of at least subsequently encoded pair of bits.
26. An apparatus for improving the quality of transmitted digital signals in a multi-level signaling system wherein digital signals representing more than one bit of information may be transmitted at more than two signal levels on a single transmission medium, the apparatus comprising:
an encoder that encodes digital values represented by sets of N bits to provide corresponding sets of P symbols, each set of P symbols being formed to reduce full-swing transitions between successive digital signal transmissions.
27. The apparatus as defined in claim 26 , wherein each set of P symbols is formed with Q bits, wherein Q is greater than N.
28. The apparatus as defined in claim 27 , wherein N=8 and Q=10.
29. The apparatus as defined in claim 27 , wherein N=10 and Q=12.
30. The apparatus as defined in claim 27 , wherein N=16 and Q=20.
31. The apparatus as defined in claim 27 , wherein N=9 and Q=10.
32. The apparatus as defined in claim 27 , wherein N=25 and Q=26.
33. The apparatus as defined in claim 26 , wherein digital signals may be transmitted at four signal levels on a single transmission medium.
34. The apparatus as defined in claim 26 , wherein digital signals may be transmitted at five signal levels on a single transmission medium.
35. The apparatus as defined in claim 26 , wherein the single transmission medium comprises a single electrical conductor.
36. The apparatus as defined in claim 26 , wherein the single transmission medium comprises a differential pair of electrical conductors.
37. The apparatus as defined in claim 26 , wherein the single transmission medium comprises an optical fiber.
38. The apparatus as defined in claim 26 , wherein each symbol represents two bits.
39. The apparatus as defined in claim 26 , wherein each set of P symbols includes at least one transition that is substantially geometrically centered.
40. The apparatus as defined in claim 26 , wherein a particular symbol in each set of P symbols is formed to ensure that undesirable transitions do not occur between neighboring sets of P symbols.
41. The apparatus as defined in claim 26 , wherein the encoder adds at least one bit having a fixed bit value to the N bits to generate each set of P symbols.
42. The apparatus as defined in claim 26 , wherein the encoder adds a parity bit to the N bits and substitutes at least one bit having a fixed bit value for at least one of the N bits to generate each set of P symbols.
43. The apparatus as defined in claim 26 , wherein the encoder forms pairs of symbols in each set of P symbols based upon the value of corresponding pairs of bits in the N bits.
44. The apparatus as defined in claim 26 , further comprising:
a transmitter that transmits the sets of P symbols;
a receiver that receives the transmitted sets of P symbols; and
a decoder that decodes the digital values represented by the sets of N bits from the transmitted sets of P symbols.
45. The apparatus as defined in claim 26 , wherein each set of P symbols is formed to eliminate full-swing transitions between at least every other successive digital signal transmission.
46. The apparatus as defined in claim 26 , wherein each set of P symbols is formed to eliminate non-full-swing transitions between at least every other successive digital signal transmission.
47. An apparatus for improving the quality of transmitted digital signals in a multi-level signaling system wherein digital signals representing more than one bit of information may be transmitted at more than two signal levels on a single transmission medium, the apparatus comprising:
means for encoding digital values represented by sets of N bits to provide corresponding sets of P symbols, each set of P symbols being formed to reduce full-swing transitions between successive digital signal transmissions.
48. An apparatus for improving the quality of transmitted digital signals in a multi-level signaling system wherein digital signals representing more than one bit of information may be transmitted at more than two signal levels on a single transmission medium, the apparatus comprising:
an encoder that encodes digital values represented by sets of N bits to provide corresponding sets of P symbols, each set of P symbols being formed to reduce non-full-swing transitions between successive digital signal transmissions.
49. The apparatus as defined in claim 48 , wherein each set of P symbols is also formed to eliminate full-swing transitions between successive digital signal transmissions.
50. The apparatus as defined in claim 48 , wherein the encoder forms each symbol in each set of P symbols based upon the value of a corresponding pair of bits in the N bits.
51. The apparatus as defined in claim 50 , wherein the encoder also forms each symbol in each set of P symbols based upon the value of at least subsequently encoded pair of bits.
52. An apparatus for improving the quality of transmitted digital signals in a multi-level signaling system wherein digital signals representing more than one bit of information may be transmitted at more than two signal levels on a single transmission medium, the apparatus comprising:
means for encoding digital values represented by sets of N bits to provide corresponding sets of P symbols, each set of P symbols being formed to reduce non-full-swing transitions between successive digital signal transmissions.