Broadband reflective phase cancelling network interface device

• US 8,793,755 B2
• Filed: 11/06/2012
• Issued: 07/29/2014
• Est. Priority Date: 11/14/2011
• Status: Active Grant

• Current Assignee: PPC Broadband Incorporated (Belden Inc.)
• Original Assignee: PPC Broadband Incorporated (Belden Inc.)
• Inventors: Montena, Noah P., Shafer, Steven K., Alkan, Erdogan, Bailey, Paul F.
• Primary Examiner(s): Goodarzi, Nasser
• Assistant Examiner(s): PIERORAZIO, MICHAEL
• Application Number:
  US13/669,805
• Publication Number:
  US 20130133019A1
• Time in Patent Office: 630 Days
• Field of Search: 725/127
• US Class Current: 725/127
• CPC Class Codes: H04N 21/61 Network physical structure; Signal processing H04B takes precedence
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/104 Switchers or splitters
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

A network interface device including a signal splitter which conducts CATV signals through an active branch circuit, the active branch circuit including an active signal conditioner which modifies characteristics of active branch signals conducted through the active branch circuit, a sensor connected to sense normal, inoperative and abnormally operative conditions, the sensor removing a control signal indicative of inoperative and abnormal operating conditions, a selectable switch connected to the active branch circuit, the selectable switch communicating the CATV signals between the CATV network and the subscriber devices when in an activated position, and the selectable switch passing the signals to a signal reduction path when in a deactivated position, the selectable switch assuming the deactivated position in response to the de-assertion of the control signal, and a phase cancellation circuit connected to the signal reduction path.

Claims

1. A network interface device operable to connect subscriber devices to a cable television (CATV) network over which (a) downstream signals are transmittable to the subscriber devices;

and (b) upstream signals are transmittable from the subscriber devices, the subscriber devices including a passive subscriber device and an active subscriber device, the network interface device comprising;

a first signal splitter configured to conduct CATV signals towards a passive branch circuit and an active branch circuit, the active branch circuit including an active signal conditioner configured to modify characteristics of active branch signals conducted through the active branch circuit;

a sensor connected to the active branch circuit, the sensor configured to determine whether power consumption of the active branch circuit is indicative of one of;

a normal condition, an inoperative condition and an abnormal condition of the network interface device, the sensor further configured to (a) supply a first control signal which is indicative of the normal condition in response to determining that the power consumption is indicative of the normal condition; and

(b) remove the first control signal in response to determining that the power consumption is indicative of one of;

the inoperative condition and the abnormal condition;

a selectable switch connected to the active branch circuit, the selectable switch having an activated position and a deactivated position, the selectable switch configured to enable communication of the CATV signals between the CATV network and the active subscriber devices when in the activated position, and the selectable switch configured to enable communication of the CATV signals to a signal reduction path when in the deactivated position, the selectable switch configured to assume the activated position in response to the supplying of the first control signal and to assume the deactivated position in response to the removing of the first control signal; and

a phase cancellation circuit connected to the signal reduction path, the phase cancellation circuit configured to split the CATV signals communicated to the signal reduction path into a first signal and a phase-delayed signal, the phase-delayed signal being substantially equal in magnitude and opposite in phase with respect to the first signal, the phase cancellation circuit further configured to recombine the first signal and the phase-delayed signal to a single, reduced CATV signal, where the reduced CATV signal cancels the first signal.

2. The network interface device of claim 1, wherein the phase cancellation circuit comprises a balun transformer in series with a 0-degree signal splitter.

3. The network interface device of claim 1, wherein the phase cancellation circuit comprises a first signal divider element and a first signal coupling element, the first signal divider element dividing the CATV signals into the first signal and the phase-delayed signal, the first signal coupling element combining the first signal and a phase-delayed signal.

4. The network interface device of claim 3, wherein the first signal divider element comprise a 180-degree signal splitter, and the first signal coupling element comprises a 0-degree combiner.

5. The network interface device of claim 1, wherein the first signal divider element comprises a 180-degree 1:

4 balun transformer, and the first signal coupling element comprises a transform matched resistance.

6. The network interface device of claim 1, wherein the first control signal to assert the activated position of the switch has sufficient electrical power to operate the active branch circuit.

18. The network interface device of claim 1, where the first signal comprises downstream signals.

19. The network interface device of claim 1, where the selectable switch comprises a relay switch.

20. The network interface device of claim 1, where the phase cancellation circuit prevents signal reflections of the CATV signals communicated to the signal reduction path from interfering with the CATV signals conducted through the first signal splitter towards the passive branch circuit.

7. A network interface device operable to connect subscriber devices to a cable television (CATV) network over which (a) downstream signals are transmittable to the subscriber devices;

and (b) upstream signals are transmittable from the subscriber devices, the subscriber devices including a passive subscriber device and an active subscriber device, the network interface device comprising;

a first signal splitter configured to conduct CATV signals towards a passive branch circuit and an active branch circuit, the active branch circuit including an active signal conditioner configured to modify characteristics of active branch signals conducted through the active branch circuit;

a sensor connected to the active branch circuit, the sensor configured to determine whether power consumption of the active branch circuit is indicative of one of;

a normal condition, an inoperative condition and an abnormal condition of the network interface device, the sensor further configured to (a) supply a first control signal which is indicative of the normal condition; and

(b) remove the first control signal in response to determining that the power consumption is indicative of one of;

the inoperative condition and the abnormal condition;

a selectable switch connected to the active branch circuit, the selectable switch having an activated position and a deactivated position, the selectable switch configured to enable communication of the CATV signals between the CATV network and the active subscriber devices when in the activated position, and the selectable switch configured to enable communication of the CATV signals to a signal reduction path when in the deactivated position, the selectable switch configured to assume the activated position in response to the supplying of the first control signal and to assume the deactivated position in response to the removing of the first control signal; and

a phase cancellation circuit connected to the signal reduction path, the phase cancellation circuit configured to split the CATV signals communicated to the signal reduction path into a plurality of signal components and communicate the plurality of signal components to a corresponding plurality of electrical paths, each of the corresponding plurality of electrical paths having different electrical lengths.

8. The network interface device of claim 7, wherein the phase cancellation circuit further comprises a first signal divider element and a first signal coupling element, the first signal divider element dividing the CATV signals into the plurality of signal components, the first signal coupling element combining the plurality of signal components on the corresponding plurality of electrical paths.

9. The network interface device of claim 8, wherein, at the first signal coupling element, each of the plurality of signal components are phase shifted with respect to each other of the plurality of signal components, wherein a single reduced-strength CATV signal is output from the first signal coupling element, where the reduced-strength CATV signal cancels at least one of the plurality of signal components.

10. A network interface device operable to connect subscriber devices to a cable television (CATV) network over which (a) downstream signals are transmittable to the subscriber devices;

and (a) valid upstream signals are transmittable from the subscriber devices, the subscriber devices including a passive subscriber device and an active subscriber device, the network interface device comprising;

a first signal splitter which configured to conduct upstream and downstream signals towards a passive branch circuit and an active branch circuit, the active branch circuit including an active signal conditioner configured to modify characteristics of active branch upstream and downstream signals conducted through the active branch circuit;

a sensor configured to determine whether power consumption of the active branch circuit is indicative of one of;

a normal condition, an inoperative condition and an abnormal condition of the network interface device, the sensor further configured to (a) supply a first control signal which is indicative of the normal condition; and

(b) remove the first control signal in response to determining that the power consumption is indicative of one of;

the inoperative condition and the abnormal condition;

a first switch connected to the active branch circuit, the first switch having an activated position and a deactivated position, the first switch configured to enable communication of the upstream and downstream CATV signals between the CATV network and the subscriber devices when in the activated position, and the first switch configured to enable communication of the upstream and downstream signals to a signal reduction path when in the deactivated position, the selectable switch configured to assume the activated position in response to the supplying of the first control signal and to assume the deactivated position in response to the removing of the first control signal;

a phase cancellation circuit connected to the signal reduction path, the phase cancellation circuit configured to create a single, reduced CATV signal based on the downstream CATV signals communicated to the phase cancellation circuit, where the reduced CATV cancels at least part of the downstream CATV signals communicated to the phase cancellation circuit; and

a second switch connected to the active branch circuit and the first control signal, the second switch having an activated position and a deactivated position, the second switch configured to enable communication of the upstream and downstream CATV signals between the CATV network and the active subscriber device when in the activated position, and the second switch configured to receive the reduced CATV upstream and downstream signal from the phase cancellation circuit when in the deactivated position, the second switch configured to assume the activated position in response to the supplying of the first control signal and to assume the deactivated position in response to the removing of the first control signal.

11. The network interface device of claim 10, the phase cancellation circuit configured to split the CATV upstream and downstream signals into a first signal and a phase-delayed signal, the phase-delayed signal being substantially equal in magnitude and opposite in phase with respect to the first signal, the phase cancellation circuit further configured to recombine the first signal and the phase-delayed signal to a single, reduced CATV upstream and downstream signal, where the reduced CATV signal cancels the first signal.

12. The network interface device of claim 10, the phase cancellation circuit connected to the signal reduction path, the phase cancellation circuit configured to split the CATV upstream and downstream signals into a plurality of signal component legs, each of the plurality of signal component legs being different electrical lengths.

13. The network interface device of claim 12, wherein the phase cancellation circuit further comprises a first signal divider element and a first signal coupling element, the first signal divider element dividing the CATV downstream signals into a plurality of signal component legs, the first signal coupling element combining the plurality of signal component legs.

14. The network interface device of claim 13, wherein at the first signal coupling element each of the plurality of signal component legs are phase shifted with respect to each other of the plurality of signal component legs, wherein a single reduced-strength CATV upstream and downstream signal is output from the first signal coupling element.

15. The network interface device of claim 10, further comprising a first filter circuit connected to the second switch, the first filter circuit comprising a first high pass filter configured to pass the downstream signals and a first low pass filter configured to pass the upstream signals.

16. The network interface device of claim 15, further comprising an active signal conditioner connected to at least one of the first high pass filter and the first low pass filter.

17. The network interface device of claim 16, further comprising a second high pass filter in communication with the first high pass filter and a second low pass filter in communication with the first low pass filter.