Systems and methods for facsimile echo cancellation
View Patent ↗The present invention is related to methods and systems for reducing or canceling echoes during fax communications. In an embodiment, during a fax call, a first fax signal from a first fax device intended for a second fax device is detected. Based at least in part on detecting the first fax signal from the first fax device or on the termination of the first fax signal, an echo audio packet is muted, wherein the echo audio packet is at least partly the result of the first fax signal being transmitted over a network, the network including at least a data network.
1. A method of canceling echoes associated with fax signaling over a network including at least a data network, during a fax call, the method comprising:
during the fax call, detecting a first fax signal from a first fax device and/or the termination of the first fax signal, wherein the first fax signal is intended for a second fax device;
muting an echo audio packet based at least in part on detecting the first fax signal from the first fax device and/or the termination of the first fax signal, wherein the audio packet is an echo of the first fax signal being transmitted over a network, the network including at least a data network.
2. The method as defined in claim 1 , wherein the audio packet is in a real time protocol stream.
3. The method as defined in claim 1 , wherein the data network is the Internet.
4. The method as defined in claim 1 , wherein the muting is performed by intercepting the audio packet, and preventing the audio packet from reaching the first fax device.
5. The method as defined in claim 1 , wherein the muting is performed at least in part by intercepting the echo audio packet, and substituting the echo audio packet with an audio packet corresponding to silent audio.
6. The method as defined in claim 1 , wherein the first fax device is a fax server.
7. The method as defined in claim 1 , wherein the second fax device is a dedicated fax machine.
8. The method as defined in claim 1 , wherein the muting is performed at least 80 ms after termination of the first fax signal.
9. The method as defined in claim 1 , wherein the muting is performed within a window beginning at least 80 ms after termination of the first fax signal, and ending 120 ms after termination of the first fax signal.
10. The method as defined in claim 1 , wherein the muting is performed during a window period selected based at least in part on a plurality of network latency measurements.
11. The method as defined in claim 1 , wherein the muting is performed during a window period selected based at least in part on network latency for at least a portion of the network between the first fax device and the second fax device.
12. The method as defined in claim 1 , further comprising measuring network latency.
13. The method as defined in claim 1 , further comprising measuring network latency using one or more of a ping, a test TCP operation, or a tone exchange.
14. The method as defined in claim 1 , wherein the echo audio packet results from a confirmation to receive (CFR) signal echo, being an echo of a CFR signal from the first fax device.
15. The method as defined in claim 1 , wherein the second fax device is coupled to a gateway that converts a circuit switched call into digital data for transmission over the data network.
16. The method as defined in claim 1 , wherein the first fax device is coupled directly to the data network via a network interface circuit.
17. The method as defined in claim 1 , wherein the second fax device initiates the fax call to the first fax device.
18. A fax system, comprising:
a data network interface; and
a line conditioner system coupled to a data network via the data network interface and further coupled to a fax device, wherein the line conditioner system is configured to detect when a first fax signal is generated by the fax device and/or to detect when the first fax signal terminates, and based at least in part on detecting when the first fax signal is generated and/or when the first fax signal terminates, mute a packet directed to the first fax device and received at the line conditioner circuit via the data network if the packet is received during a selected first period of time.
19. The fax system as defined in claim 18 , wherein the fax device is a fax server or a dedicated fax machine.
20. The fax system as defined in claim 18 , wherein the line conditioner system further comprises a server.
21. The fax system as defined in claim 18 , wherein the line conditioner system mutes the packet by preventing the packet from reaching the fax device.
22. The fax system as defined in claim 18 , wherein the packet is an audio packet resulting from an echo of the first fax signal.
23. The fax system as defined in claim 18 , further comprising a gateway coupled to the line conditioner system, wherein the gateway converts digital data from the line conditioner system to a circuit-switched call.
24. The fax system as defined in claim 18 , wherein the first period of time begins at least 80 ms after the first signal is generated.
25. The fax system as defined in claim 18 , wherein the first period of time is at least 40 ms long.
26. The fax system as defined in claim 18 , wherein the first fax signal is a confirmation to receive (CFR) signal.
27. The fax system as defined in claim 18 , wherein the first fax signal is a handshaking signal directed to a second fax device.
28. The fax system as defined in claim 18 , further comprising the fax device.
29. A method of processing fax signaling carried over a network including at least a data network, the method comprising:
monitoring a first fax signal from a first fax system directed to a second fax system; and
based at least in part upon the monitoring of the first fax signal from the first fax system, muting an audio packet directed to the first fax system, wherein the audio packet is at least partly the result of the first fax signal being transmitted over a network, the network including at least a data network.
30. The method as defined in claim 29 , wherein the audio packet is in a real time protocol stream.
31. The method as defined in claim 29 , wherein the data network is the Internet.
32. The method as defined in claim 29 , wherein the muting is performed by a line conditioner system that receives the audio packet, and prevents the audio packet from being received by the first fax system.
33. The method as defined in claim 29 , wherein the muting is performed at least in part by receiving the audio packet before it is received by the first fax system, and substituting the audio packet with another packet.
34. The method as defined in claim 29 , wherein the first fax system includes a fax server and/or a dedicated fax machine.
35. The method as defined in claim 29 , wherein the muting is performed at least 80 ms after the first fax signal is generated.
36. The method as defined in claim 29 , wherein the fax signal is a handshaking signal transmitted by the first fax system prior to the second fax system transmitting an initial fax page in a fax call associated with the first fax signal.
37. The method as defined in claim 29 , wherein timing for the muting of the audio packet is selected based at least in part on a plurality of network latency measurements.
38. The method as defined in claim 29 , wherein timing for the muting of the audio packet is selected based at least in part on network latency for at least a portion of the network between the first fax system and the second fax system.
39. The method as defined in claim 29 , further comprising: measuring network latency, and using the measured network latency to determine muting timing.
40. The method as defined in claim 29 , further comprising:
measuring network latency using one or more of a ping, a test TCP operation, or a tone exchange; and
using the measured network latency to determine muting timing.
41. The method as defined in claim 29 , wherein the audio packet is the result of an echo of the first fax signal.
42. The method as defined in claim 29 , wherein the second fax system is coupled to a gateway that converts a circuit switched call into digital data for transmission over the data network.
43. The method as defined in claim 29 , wherein the first fax system is coupled directly to the data network via a network interface circuit.
44. A method of canceling echoes associated with fax signaling over a network including at least a data network, the method comprising:
during a fax call, detecting a first fax signal from a first fax device intended for a second fax device;
muting an audio packet based at least in part on detecting the first fax signal from the first fax device and/or termination of at least one fax signal, wherein the audio packet includes an echo of the at least one fax signal being transmitted over a network, the network including at least a data network.
45. The method as defined in claim 44 , wherein the audio packet is in a real time protocol stream.
46. The method as defined in claim 44 , wherein the data network is an Internet Protocol network.
47. The method as defined in claim 44 , wherein the second fax device is configured to participate in a fax call over an Internet Protocol (IP) network.
48. The method as defined in claim 44 , wherein the second fax device is configured to participate in a fax call over a switched telephone network.
49. The method as defined in claim 44 , wherein the second fax device is configured to participate in a voice call over a switched telephone network.
50. The method as defined in claim 44 , wherein the muting is performed by intercepting the audio packet, and preventing the audio packet from reaching the second fax device.
51. The method as defined in claim 44 , wherein the muting is performed at least in part by intercepting the audio packet, and substituting the audio packet with a different audio packet corresponding to silent audio.
52. The method as defined in claim 44 , wherein the second fax device is a voice and fax processing system.
53. The method as defined in claim 44 , wherein the muting is performed during a period selected based at least in part on a plurality of network latency measurements.
54. The method as defined in claim 44 , wherein the wherein the muting is performed during a period selected based at least in part on network latency for at least a portion of the network between the first fax device and the second fax device.
55. The method as defined in claim 44 , further comprising measuring network latency.
56. The method as defined in claim 44 , further comprising measuring network latency using a ping, a test TCP operation, and/or a tone exchange.
57. The method as defined in claim 44 , wherein the second fax signal is a confirmation to receive (CFR) signal.
58. The method as defined in claim 44 , wherein the audio packet results from a confirmation to receive (CFR) signal echo.
59. The method as defined in claim 44 , wherein the at least one fax signal is a training-related signal.
60. The method as defined in claim 44 , wherein the first fax device is coupled to a gateway that converts a circuit switched call into digital data for transmission over the data network.
61. The method as defined in claim 44 , wherein the second fax device is coupled directly to the data network via a network interface circuit.
62. The method as defined in claim 44 , wherein the first fax device initiates the fax call to the second fax device.
63. A line conditioner system, comprising:
a first interface configured to communicate data via a data network; and
a second interface configured to communicate with one or more fax devices,
wherein the line conditioner system is configured to detect at least one fax signal generated by at least one fax device and/or to detect the termination of at least one fax signal, wherein the at least one fax signal is transmitted at least in part over the data network, and based at least in part on such detection, to mute at least one packet directed to at least one fax device, wherein the at least one packet is received at the line conditioner system via the data network.
64. The line conditioner as defined in claim 63 , wherein the line conditioner system further comprises a network server.
65. The line conditioner as defined in claim 63 , wherein the data network is an Internet Protocol network.
66. The line conditioner as defined in claim 63 , wherein the line conditioner system mutes the packet by preventing the packet from reaching the at least one fax device.
67. The line conditioner as defined in claim 63 , wherein the packet is an audio packet resulting from an echo of the at least one fax signal.
68. The line conditioner as defined in claim 63 , further comprising a gateway, wherein the gateway converts digital data from the line conditioner system to a circuit-switched call.
69. The line conditioner as defined in claim 63 , wherein the at least one fax signal is a confirmation to receive (CFR) signal.
70. The line conditioner as defined in claim 63 , wherein the at least one fax signal is a handshaking signal directed to a first fax device.
71. The line conditioner as defined in claim 63 , further comprising the at least one fax device.
72. The line conditioner as defined in claim 63 , wherein the muting is performed during a period selected based at least in part on a plurality of network latency measurements.
73. The line conditioner as defined in claim 63 , wherein the muting is performed at least in part by intercepting an audio packet, and substituting the audio packet with an audio packet corresponding to silent audio.
74. A method of processing fax signaling over a network including at least a data network, the method comprising:
monitoring a fax signal from a first fax system directed to a second fax system; and
based at least in part upon the monitoring of the fax signal from the first fax system, muting an audio packet that would otherwise be received by the first fax system, wherein the audio packet is at least partly the result of the fax signal being transmitted over a network, the network including at least a data network.
75. The method as defined in claim 74 , wherein the audio packet is in a real time protocol stream.
76. The method as defined in claim 74 , wherein the data network is an Internet Protocol network.
77. The method as defined in claim 74 , wherein the muting further comprises:
receiving the audio packet at a line conditioner system; and
preventing the audio packet from being received by the first fax system.
78. The method as defined in claim 74 , wherein the muting is performed at least in part by receiving the audio packet before it is received by the first fax system, and substituting the audio packet with another packet.
79. The method as defined in claim 74 , wherein the muting is performed 80 ms or more after the fax signal is generated.
80. The method as defined in claim 74 , wherein the fax signal is a handshaking signal transmitted by the first fax system prior to the second fax system transmitting an initial fax page in a fax call associated with the fax signal.
81. The method as defined in claim 74 , wherein timing for the muting of the audio packet is selected based at least in part on a plurality of network latency measurements.
82. The method as defined in claim 74 , wherein timing for the muting of the audio packet is selected based at least in part on network latency for at least a portion of the network between the first fax system and the second fax system.
83. The method as defined in claim 74 , further comprising:
measuring network latency; and
using the measured network latency to determine muting timing.
84. The method as defined in claim 74 , further comprising:
measuring network latency using one or more of a ping, a test TCP operation, or a tone exchange; and
using the measured network latency to determine muting timing.
85. The method as defined in claim 74 , wherein the audio packet is the result of an echo of the fax signal.
86. The method as defined in claim 74 , wherein the second fax system is coupled to a gateway that converts a circuit switched call into digital data for transmission over the data network.
87. The method as defined in claim 74 , wherein the first fax system is coupled directly to the data network via a network interface circuit.