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. An apparatus comprising:
an article of manufacture having a non-transitory machine-readable storage medium containing stored instructions that program a machine to monitor a network for a fax signal that is transmitted from a first fax device and is directed to a second fax device, wherein the network includes a data packet network and a circuit switched telephone network, to detect the fax signal from the first fax device, and to mute an echo audio packet in the network, that is directed to the first fax device, based in part on detecting the fax signal from the first fax device.
2. The apparatus of claim 1 , wherein the data packet network is the Internet.
3. The apparatus of claim 1 , wherein the fax signal is a confirmation to receive signal, which indicates that the first fax device is ready to receive a fax page from the second fax device using an incoming call to the first fax device.
4. The apparatus of claim 1 , wherein the instructions are such that the muting comprises intercepting the echo audio packet and substituting the echo audio packet with an audio packet containing silent audio.
5. The apparatus of claim 1 , wherein the echo audio packet is muted only in response to waiting a predetermined time interval following detection of the fax signal.
6. The apparatus of claim 5 , wherein the predetermined time interval is at least 80 ms after termination of the fax signal.
7. The apparatus of claim 1 , wherein the echo audio packet is muted only during a window period beginning at least 80 ms after termination of the fax signal, and ending 120 ms after termination of the fax signal.
8. The-apparatus of claim 1 , containing additional instructions that program the machine to measure network latency.
9. The apparatus of claim 8 , wherein the echo audio packet is muted during a window period selected based at least in part on a plurality of network latency measurements.
10. The apparatus of claim 8 , wherein the echo audio packet is muted 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.
11. An apparatus comprising:
an article of manufacture having anon-transitory machine-readable storage medium containing stored instructions that program a machine to monitor a network for a fax signal that is transmitted from a first fax device and is directed to a second fax device, wherein the network includes a data packet network and a circuit switched telephone network, to detect the termination of the fax signal from the first fax device, and to mute an echo audio packet in the network, that is directed to the first fax device, based in part on detecting the termination of the fax signal from the first fax device.
12. The apparatus of claim 11 , wherein the data network is the Internet.
13. The apparatus of claim 11 , wherein the fax signal is a confirmation to receive signal, which indicates that the first fax device is ready to receive a fax page from the second fax device using an incoming call to the first fax device.
14. The apparatus of claim 11 , wherein the echo audio packet is muted only in response to waiting a predetermined time interval following detection of the termination of the fax signal.
15. The apparatus of claim 14 , wherein the predetermined time interval is at least 80 ms after termination of the fax signal.
16. The-apparatus of claim 11 , wherein the echo audio packet is muted only during a window period beginning at least 80 ms after termination of the fax signal, and ending 120 ms after termination of the fax signal.
17. The apparatus of claim 11 , containing additional instructions that program the machine to measure network latency.
18. The apparatus of claim 17 , wherein the echo audio packet is muted during a window period selected based at least in part on a plurality of network latency measurements.
19. The apparatus of claim 17 , wherein the echo audio packet is muted 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.
20. An apparatus comprising:
an article of manufacture having a non-transitory machine-readable storage medium containing stored instructions that program a machine to monitor a network for a fax signal that is transmitted from a first fax device and is directed to a second fax device, wherein the network includes a data packet network and a circuit switched telephone network, to detect the fax signal from the first fax device, and to prevent an echo audio packet in the network, that is directed to the first fax device, from reaching the first fax device only in response to waiting a predetermined time interval following detection of the fax signal.
21. The apparatus of claim 20 , wherein the data packet network is the Internet.
22. The apparatus of claim 20 , wherein the fax signal is a confirmation to receive signal, which indicates that the first fax device is ready to receive a fax page from the second fax device using an incoming call to the first fax device.
23. The apparatus of claim 20 , wherein the predetermined time interval is at least 80 ms after termination of the fax signal.
24. The apparatus of claim 20 , wherein the echo audio packet is prevented from reaching the first fax device during a time window beginning at least 80 ms after termination of the fax signal, and ending 120 ms after termination of the fax signal.