Claims
- 1. A method of operating a communication device, said method comprising:
receiving a periodic signal via a communication channel; detecting a periodic component of quantization error in said received periodic signal; and based on said detecting, adapting a receiver to a characteristic of said communication channel.
- 2. The method of claim 1,
wherein said periodic component of quantization error is indicative of an absence analog-to-digital conversions in the communication channel from a remote communication device.
- 3. The method of claim 1,
wherein said periodic component of quantization error is indicative of an absence of unsynchronized quantization error introducing conversions in the transmission path from a remote communication device.
- 4. The method of claim 1,
wherein said periodic signal is received during an initialization period.
- 5. The method of claim 1, wherein said adapted receiver is that of said communication device.
- 6. The method of claim 1,
wherein said adapting includes causing the receiver to enter a digital mode of operation.
- 7. The method of claim 1,
wherein said adapting includes causing said receiver to enter an analog mode of operation when a level of said periodic component of quantization error is less than a threshold.
- 8. The method of claim 1,
wherein said adapting includes causing the receiver to forgo compensation for a particular impairment.
- 9. The method of claim 8,
wherein said forgone impairment compensation includes far-end echo cancellation.
- 10. The method of claim 8,
wherein said forgone impairment compensation includes phase jitter compensation.
- 11. The method of claim 8,
wherein said forgone impairment compensation includes frequency shift compensation.
- 12. The method of claim 8,
wherein said detection of said periodic component of quantization error is indicative of a direct digital connection; and wherein said forgone impairment compensation is unnecessary in the context of said direct digital connection.
- 13. A method of operating a communication device, said method comprising:
receiving a signal from a remote device; filtering said received signal to detect a periodic component of quantization error therein; responsive to a detection of said periodic component of quantization error, causing said communication device to enter a first mode of operation; and responsive to detection of less than a threshold level of said periodic component, causing said communication device to enter a second mode of operation.
- 14. The method of claim 13,
wherein said first mode includes a digital receive mode; and wherein said second mode includes an analog receive mode.
- 15. The method of claim 13, wherein said signal is received during an initialization period.
- 16. A method as recited in claim 13,
wherein absence of more than said threshold level of said periodic component is indicative of at least one unsynchronized quantization error introducing conversion in a transmission path from said communication device.
- 17. A method as recited in claim 13,
wherein absence of more than said threshold level of said periodic component is indicative of at least one analog-to-digital conversion in a transmission path from said remote device.
- 18. A method as recited in claim 15,
wherein said communication device is an analog modem connected to an analog portion of a transmission path from said remote device; and wherein absence of more than said threshold level of said periodic component is indicative that the transmission path from said remote device includes at least one other analog portion.
- 19. A method as recited in claim 15,
wherein said second mode of operation includes demodulation of a quadrature amplitude modulated (QAM) signal.
- 20. A method of selecting between a first and a second receive modes in a modem, said method comprising:
determining whether periodic quantization noise is a substantial component of noise in a received periodic signal; and selecting a receive mode based on said determination.
- 21. A method as in claim 20,
wherein said selected receive mode includes a digital receive mode.
- 22. A method as in claim 20,
wherein said selected receive mode includes an analog receive mode.
- 23. The method as in claim 20, further comprising:
causing the receiver to forgo compensation for a particular impairment.
- 24. The method as in claim 23,
wherein said forgone impairment compensation includes far-end echo cancellation.
- 25. The method as in claim 23,
wherein said forgone compensation includes phase jitter compensation.
- 26. The method as in claim 23,
wherein said forgone compensation includes frequency shift compensation.
- 27. The method as in claim 23.
wherein said forgone compensation includes one or more of a far-end echo cancellation, a phase jitter compensation and a frequency shift compensation.
- 28. A method as in claim 20,
wherein said substantial component is at least 3 dB greater than another component of said noise.
- 29. A communication device configured to detect a periodic component of quantization error in a received signal and select an operating mode based thereon.
- 30. The communication device of claim 29, at least partially embodied as a modem.
- 31. The communication device of claim 29, wherein the selected operating mode is a receive mode thereof.
- 32. The communication device of claim 29, wherein the selected operating mode is a receive mode for communication involving the communication device.
- 33. The communication device of claim 29,
wherein the selection is of receive path signal processing appropriate to a detected type of said signal.
- 34. The communication device of claim 29, wherein said signal is digitally encoded signal.
- 35. The communication device of claim 29, wherein said signal is analog signal.
- 36. The communication device of claim 29 further comprising:
at least one filter configured to detect said periodic component of quantization error in said received signal.
- 37. The communication device of claim 36,
wherein said filter has coefficients defined to distinguish between an L1L2 initialization sequence with and without said periodic component of quantization error.
- 38. The communication device of claim 36,
wherein said signal includes a predetermined initialization sequence signal of known period; and wherein said filter is operable during an initialization period to detect said periodic component of quantization error in said predetermined initialization sequence signal.
- 39. The communication device of claim 36, further comprising: receive path signal processing structures, coupled to the filter, configured to demodulate said signal.
- 40. The communication device of claim 39, wherein
said receive path signal processing structures are further configured to demodulate said signal upon successful detection of said periodic component.
- 41. The communication device of claim 29,
wherein said periodic component is introduced, at least in part, by operation of a converter.
- 42. The communication device of claim 41, wherein said converter includes a mu-law or A-law PCM converter.
- 43. The communication device of claim 41,
wherein said converter is embodied in private branch exchange equipment.
- 44. The communication device of claim 41,
wherein said converter is embodied in multiplexing equipment.
- 45. The communication device of claim 41,
coupled to a communications path from said remote communication device, wherein said periodic component is substantially obscured by operation of an unsynchronized quantization error introducing conversion along said communications path.
- 46. The communication device of claim 45,
wherein said unsynchronized quantization error conversion is associated with operation of private branch exchange equipment.
- 47. The communication device of claim 45,
wherein said unsynchronized quantization error conversion is associated with operation of public switched telecommunication network.
- 48. The communication device of claim 45,
wherein said unsynchronized quantization error conversion is associated with operation of multiplexing equipment.
- 49. The communication device of claim 29,
at least partially embodied as one or more of a computer, a portable or handheld communications device, a personal digital assistant-type device, a set-top box, a cable modem, a non-voice band communications device, and a data-capable mobile phone.
- 50. A computer program product encoded by or transmitted in at least one computer readable medium, the computer program product including an instruction sequence executable to:
detect a periodic component of quantization error in a periodic signal received via a communication channel and to select; and select based on said detecting, an adaptation of a receiver to said communication channel.
- 51. The computer program product of claim 50, wherein the at least one computer readable medium is selected from a set of a disk, tape or other magnetic, optical, or electronic storage medium and a network, wireline, wireless or other communications medium.
- 52. The computer program product of claim 50,
wherein said periodic component of quantization error is indicative of an absence analog-to-digital conversions in the communication channel from a remote communication device.
- 53. The computer program product of claim 50,
wherein said periodic component of quantization error is indicative of an absence of unsynchronized quantization error introducing conversions in the transmission path from a remote communication device.
- 54. The computer program product of claim 50,
wherein said periodic signal is received during an initialization period.
- 55. The computer program product of claim 50,
wherein said adaptation includes causing the receiver to enter a digital mode of operation.
- 56. The computer program product of claim 50,
wherein said adaptation includes causing said receiver to enter an analog mode of operation when a level of said periodic component of quantization error is less than a threshold.
- 57. The computer program product of claim 50,
wherein said adaptation includes causing the receiver to forgo compensation for a particular impairment.
- 58. The computer program product of claim 57,
wherein said forgone impairment compensation includes far-end echo cancellation.
- 59. The computer program product of claim 57,
wherein said forgone impairment compensation includes phase jitter compensation.
- 60. The computer program product of claim 57,
wherein said forgone impairment compensation includes frequency shift compensation.
- 61. The computer program product of claim 57,
wherein said detection of said periodic component of quantization error is indicative of a direct digital connection; and wherein said forgone impairment compensation is unnecessary in the context of said direct digital connection.
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] The present application is continuation application of and claims priority from U.S. patent application Ser. No. 09/256,922 filed on Feb. 24, 1999.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09256922 |
Feb 1999 |
US |
Child |
10299929 |
Nov 2002 |
US |