Transmit, receive, and cross-talk cancellation filters for back channelling
View Patent ↗Systems and methods are provided herein for interfacing a first digital device with a second digital device. An exemplary method includes the steps of combining one of a plurality of digital content channels and a back channel to form a composite channel, the back channel for transmitting information from the second multi-media digital device to the first multi-media digital device, converting a digital content channel and the composite channel from the first digital device into a plurality of single-ended digital content channels, transporting the plurality of single-ended digital content channels from the first digital device to the second digital device, and converting the single-ended digital content channels back into the digital content channel and the composite channel that are supplied to the second digital device. Cross-talk interference is reduced between the back channel and one of the plurality of digital content channels via a cross-talk cancellation filter.
1. An interface system for coupling a first digital device with a second digital device over a cable, comprising:
circuitry for combining a high frequency digital content channel for transmitting digital content from the first digital device to the second digital device and a low frequency back channel for transmitting information from the second digital device to the first digital device to form a composite channel, the circuitry comprising,
a main channel transmit filter coupled between the first digital device and the cable and configured to filter the digital content channel,
a back channel receive filter coupled between the first digital device and the cable and configured to filter the back channel,
a back channel transmit filter coupled between the cable and the second digital device and configured to filter the back channel,
a main channel receive filter coupled between the cable and the second digital device and configured to filter the digital content channel, and
at least one cross-talk cancellation filter coupled between the digital content channel and the back channel and configured to reduce cross-talk interference between the back channel and the digital content channel;
wherein the second digital device includes a receiver having a differential pair of inputs that includes a first differential input and a second differential input, the main channel receive filter is coupled between the first differential input and the cable, and a cross-talk cancellation filter is coupled between the second differential input and the back channel.
2. The interface system of claim 1 , wherein the cross-talk cancellation filter is configured to reduce cross-talk interference from the back channel to the digital content channel, the cross-talk cancellation filter being coupled between the cable and the second digital device.
3. The interface system of claim 2 , wherein the cross-talk cancellation filter subtracts a cross-talk signal from the digital content channel.
4. The interface system of claim 2 , wherein the cross-talk cancellation filter is matched to a cross-talk transfer function related to the back channel and the digital content channel such that the effective cross-talk between the back channel and the digital content channels is about zero.
5. The interface system of claim 1 , wherein the cross-talk cancellation filter is configured to reduce cross-talk interference from the digital content channel to the back channel, the cross-talk cancellation filter being coupled between the first digital device and the cable.
6. The interface system of claim 5 , wherein the cross-talk cancellation filter is matched to a cross-talk transfer function related to the back channel and the digital content channel such that the effective cross-talk between the digital content channel and the back channel is about zero.
7. The interface system of claim 5 , wherein the cross-talk cancellation filter subtracts a cross-talk signal from the back channel.
8. The interface system of claim 7 , wherein the subtraction of a cross-talk signal uses a complementary output of a transmitter of the first digital device.
9. The interface system of claim 7 , wherein the subtraction utilizes a virtual ground of an active-resistor-capacitor (RC) filter.
10. The interface system of claim 1 , further comprising a second cross-talk cancellation filter configured to reduce cross-talk interference between the back channel and the digital content channel.
11. The interface system of claim 1 , wherein the back channel transmit filter is a low-pass filter.
12. The interface system of claim 1 , wherein the back channel transmit filter is a pre/de-emphasis filter.
13. The interface system of claim 1 , wherein the back channel transmit filter uses an active-RC configuration.
14. The interface system of claim 1 , wherein the back channel receive filter is an equalizing filter.
15. The interface system of claim 1 , wherein the back channel receive filter is a low-pass filter.
16. The interface system of claim 1 , wherein the back channel receive filter is an out-of-band noise rejection filter.
17. The interface system of claim 1 , wherein the back channel receive filter uses an active-RC configuration.
18. The interface system of claim 1 , wherein the main channel transmit filter is a high-pass filter.
19. The interface system of claim 1 , wherein the main channel receive filter is a high-pass filter.
20. The interface system of claim 1 , wherein the cable is a coaxial cable or a twisted pair cable.
21. The interface system of claim 1 , wherein the cable carries single ended or differential signals.
22. The interface system of claim 1 , wherein the interface system is serial digital interface (SDI)-based system.
23. The interface system of claim 1 , wherein the cross-talk cancellation filter matches a characteristic impedance of a transmission medium that includes the cable.
24. The interface system of claim 1 , wherein the first digital device and the second digital device are multimedia devices.
25. The interface system of claim 1 , wherein the back channel carries configuration and control data, or audio data.
26. An interface system for coupling a first digital device with a second digital device over a cable, comprising:
circuitry for combining a high frequency digital content channel for transmitting digital content from the first digital device to the second digital device and a low frequency back channel for transmitting information from the second digital device to the first digital device to form a composite channel, the circuitry comprising,
a main channel transmit filter coupled between the first digital device and the cable and configured to filter the digital content channel,
a back channel receive filter coupled between the first digital device and the cable and configured to filter the back channel,
a back channel transmit filter coupled between the cable and the second digital device and configured to filter the back channel,
a main channel receive filter coupled between the cable and the second digital device and configured to filter the digital content channel, and
at least one a cross-talk cancellation filter coupled between the digital content channel and the back channel and configured to reduce cross-talk interference between the back channel and the digital content channel;
wherein the first digital device includes a transmitter having a complementary pair of outputs that includes a first differential output and a second differential output, the main channel transmit filter is coupled between the first differential output and the cable, and a cross-talk cancellation filter is coupled between the second differential output and the back channel.
27. The interface system of claim 26 , wherein the cross-talk cancellation filter is configured to reduce cross-talk interference from the back channel to the digital content channel, the cross-talk cancellation filter being coupled between the cable and the second digital device.
28. The interface system of claim 27 , wherein the cross-talk cancellation filter subtracts a cross-talk signal from the digital content channel.
29. The interface system of claim 27 , wherein the cross-talk cancellation filter is matched to a cross-talk transfer function related to the back channel and the digital content channel such that the effective cross-talk between the back channel and the digital content channels is about zero.
30. The interface system of claim 26 , wherein the cross-talk cancellation filter is configured to reduce cross-talk interference from the digital content channel to the back channel, the cross-talk cancellation filter being coupled between the first digital device and the cable.
31. The interface system of claim 30 , wherein the cross-talk cancellation filter is matched to a cross-talk transfer function related to the back channel and the digital content channel such that the effective cross-talk between the digital content channel and the back channel is about zero.
32. The interface system of claim 30 , wherein the cross-talk cancellation filter subtracts a cross-talk signal from the back channel.
33. The interface system of claim 32 , wherein the subtraction of a cross-talk signal uses a complementary output of a transmitter of the first digital device.
34. The interface system of claim 32 , wherein the subtraction utilizes a virtual ground of an active-resistor-capacitor (RC) filter.
35. The interface system of claim 26 , further comprising a second cross-talk cancellation filter configured to reduce cross-talk interference between the back channel and the digital content channel.
36. The interface system of claim 26 , wherein the back channel transmit filter is a low-pass filter.
37. The interface system of claim 26 , wherein the back channel transmit filter is a pre/de-emphasis filter.
38. The interface system of claim 26 , wherein the back channel transmit filter uses an active-RC configuration.
39. The interface system of claim 26 , wherein the back channel receive filter is an equalizing filter.
40. The interface system of claim 26 , wherein the back channel receive filter is a low-pass filter.
41. The interface system of claim 26 , wherein the back channel receive filter is an out-of-band noise rejection filter.
42. The interface system of claim 26 , wherein the back channel receive filter uses an active-RC configuration.
43. The interface system of claim 26 , wherein the main channel transmit filter is a high-pass filter.
44. The interface system of claim 26 , wherein the main channel receive filter is a high-pass filter.
45. The interface system of claim 26 , wherein the cable is a coaxial cable or a twisted pair cable.
46. The interface system of claim 26 , wherein the cable carries single ended or differential signals.
47. The interface system of claim 26 , wherein the interface system is a serial digital interface (SDI)-based system.
48. The interface system of claim 26 , wherein the cross-talk cancellation filter matches a characteristic impedance of a transmission medium that includes the cable.
49. The interface system of claim 26 , wherein the first digital device and the second digital device are multimedia devices.
50. The interface system of claim 26 , wherein the back channel carries configuration and control data, or audio data.
51. An interface system for coupling a first digital device with a second digital device over a cable, comprising:
circuitry for combining a high frequency digital content channel for transmitting digital content from the first digital device to the second digital device and a low frequency back channel for transmitting information from the second digital device to the first digital device to form a composite signal;
the first digital device including a transmitter having a complementary pair of outputs that includes a first differential output and a second differential output, wherein the first differential output is coupled to the high frequency digital content channel;
the second digital device including a receiver having a differential pair of inputs that includes a first differential input and a second differential input, wherein the first differential input is coupled to the high frequency content channel;
the circuitry including one or more cross-talk cancellation filters configured to reduce cross-talk interference between the back channel and the digital content channel,
wherein the one or more cross-talk cancellation filters include at least one of:
a first cross-talk cancellation filter coupled between the second differential output of the transmitter and the low frequency back channel, and
a second cross-talk cancellation filter coupled between the second differential input of the receiver and the low frequency back channel.
52. The interface system of claim 51 , wherein the circuitry further includes a main channel receive filter coupled between the first differential input of the receiver and the high frequency content channel.
53. The interface system of claim 51 , wherein the circuitry further includes a main channel transmit filter coupled between the first differential output of the transmitter and the high frequency content channel.
54. The interface system of claim 51 , wherein the circuitry further includes a back channel receive filter coupled between the first digital device and the low frequency back channel.
55. The interface system of claim 51 , wherein the circuitry further includes a back channel transmit filter coupled between the second digital device and the low frequency back channel.