Passive-Active Terminal Adapter and Method Having Automatic Return Loss Control

• US 20100017842A1
• Filed: 07/17/2008
• Published: 01/21/2010
• Est. Priority Date: 07/17/2008
• Status: Active Grant

• Current Assignee: PPC Broadband Incorporated (Belden Inc.)
• Original Assignee: PPC Broadband Incorporated (Belden Inc.)
• Inventors: Wells, Chad T.
• Granted Patent: US 9,363,469 B2
• Time in Patent Office: Days
• US Class Current: 725/149
• CPC Class Codes: H04M 11/066 Telephone sets adapted for data transmision
• CPC Class Codes: H04N 21/25 Management operations performed by the server for facilitating the content distribution or administrating data related to end-users or client devices, e.g. end-user or client device authentication, learning user preferences for recommending movies maintenance or administration in data networks H04L41/00
• CPC Class Codes: H04N 21/44231 Monitoring of peripheral device or external card, e.g. to detect processing problems in a handheld device or the failure of an external recording device configuring of peripheral devices in general G06F9/4411; reporting information sensed by appliance or service execution status of appliance services in a home automation network H04L12/2823; monitoring the status of connected device in data switched networks H04L43/0817
• CPC Class Codes: H04N 21/4424 Monitoring of the internal components or processes of the client device, e.g. CPU or memory load, processing speed, timer, counter or percentage of the hard disk space used error monitoring in general G06F11/30; arrangements for monitoring conditions of receiving stations in broadcast systems H04H60/32; diagnosis, testing or measuring for television receivers H04N17/04
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 5/63 Generation or supply of power specially adapted for television receivers
• CPC Class Codes: H04N 7/102 Circuits therefor, e.g. noise reducers, equalisers, amplifiers H04N7/108 takes precedence
• CPC Class Codes: H04N 7/104 Switchers or splitters
• CPC Class Codes: H04N 7/173 with two-way working, e.g. subscriber sending a programme selection signal

Abstract

Return loss due to excessive signal reflection into a cable television (CATV) network from an inoperative or abnormally operative terminal adapter is minimized, to communicate enhanced passive downstream signals to passive subscriber devices such as “life-line” telephone sets. A predetermined termination impedance is substituted for an active branch circuit of the terminal adapter whenever reduced input voltage, over-current or under-current conditions exist in the terminal adapter.

Claims

1. A passive-active terminal adapter for use in connecting subscriber devices to receive downstream signals from a cable television network and to deliver upstream signals from the subscriber devices to the network, in which electrical power is supplied to operate the terminal adapter, comprising:

a signal splitter which separates downstream signals into active branch downstream signals and passive branch downstream signals;

a passive branch circuit receptive of the passive branch downstream signals;

an active branch circuit receptive of the active branch downstream signals, the active branch circuit including an active signal conditioner which modifies characteristics of the active branch downstream signals conducted through the active branch circuit;

a sensor connected to sense power consumption of the active branch circuit indicative of normal, inoperative and abnormally operative conditions of the terminal adapter, the sensor supplying a first control signal indicative of normal operating conditions and supplying a second control signal indicative of inoperative and abnormal operating conditions;

a termination impedance having a predetermined impedance characteristic; and

a switch receptive of the first and second control signals and connected to the signal splitter and the active branch circuit and the termination impedance, the switch having a first operative position which conducts the active branch downstream signals from the splitter to the active branch circuit, the switch also having a second operative position which conducts the active branch downstream signals from the splitter to the termination impedance and which disconnects the active branch circuit from the splitter, the switch assuming the first operative position in response to the first control signal and assuming the second operative position in response to the second control signal.

2. A passive-active terminal adapter as defined in claim 1, wherein:

the active branch circuit further includes an active signal conditioner for modifying characteristics of the active branch downstream signals conducted through the active branch circuit; and

the sensor senses power consumption by sensing current consumption.

3. A passive-active terminal adapter as defined in claim 2, wherein:

the active signal conditioner includes an amplifier.

4. A passive-active terminal adapter as defined in claim 1, wherein:

the sensor senses current consumed by the terminal adapter and voltage supplied to the terminal adapter;

the sensor determines the normal operating condition, the inoperative condition and the abnormally operative condition from an amount of current consumed and a level of voltage supplied.

5. A passive-active terminal adapter as defined in claim 4, wherein:

the sensor determines the normal operating condition and the abnormally operative condition relative to a predetermined range of current consumption.

6. A passive-active terminal adapter as defined in claim 5, wherein:

the sensor senses an amount of current consumption greater than the predetermined range of current consumption to determine one abnormally operative condition.

7. A passive-active terminal adapter as defined in claim 5, wherein:

the sensor senses and amount of current consumption less than the predetermined range of current consumption to determine an abnormally operative condition.

8. A passive-active terminal adapter as defined in claim 4, wherein:

the sensor determines the normal operative condition and the inoperative condition relative to a predetermined range of voltage of the power supplied to the terminal adapter.

9. A passive-active terminal adapter as defined in claim 1, wherein:

the predetermined impedance characteristic of the termination impedance is a predetermined impedance value which minimizes return loss in the passive branch signals when the switch is in the second operative position.

10. A passive-active terminal adapter as defined in claim 1, wherein:

the predetermined impedance characteristic of the termination impedance has a predetermined impedance value which minimizes signal reflections through the splitter into the cable television network when the switch is in the second operative position.

11. A passive-active terminal adapter as defined in claim 10, for use with both passive subscriber devices and active subscriber devices, and for connection to a coaxial cable through which the downstream and upstream signals are conducted from and to the cable television network, the coaxial cable having a characteristic impedance, and the terminal adapter further comprising:

an input port through which the upstream and downstream signals are conducted;

a passive port through which the passive branch signals are conducted to a passive subscriber device;

an active port through which active branch downstream signals are conducted to at least one active subscriber device; and

wherein;

the input port is adapted to be connected to the coaxial cable; and

the predetermined characteristic of the termination impedance is substantially equal to the characteristic impedance of a coaxial cable.

12. A passive-active terminal adapter as defined in claim 11, wherein:

the one passive subscriber device comprises a voice modem and a telephone set.

13. A method of minimizing return loss in downstream signals conducted through a passive branch circuit of a passive-active terminal adapter which also includes an active branch circuit which conducts downstream signals, comprising:

connecting the active and passive branch circuits of the terminal adapter to receive downstream signals from a cable television network;

recognizing an abnormally operative condition of the terminal adapter when connected to the cable television network; and

in response to such recognition,

substituting a termination impedance having a predetermined impedance characteristic for the active branch circuit.

14. A method as defined in claim 13, further comprising:

connecting a voice modem and a telephone set to the passive branch circuit to receive downstream signals from the cable television network.

15. A method as defined in claim 13, further comprising:

supplying electrical power to the terminal adapter; and

recognizing a characteristic of the electrical power supplied to the signal conditioner as indicative of the abnormally operative condition.

16. A method as defined in claim 13, further comprising:

sensing current consumed by the terminal adapter and voltage supplied to the terminal adapter; and

recognizing a normal operating condition, an inoperative condition and the abnormally operative condition from the sensed amount of current consumed and the sensed level of voltage supplied.

17. A method as defined in claim 16, further comprising:

recognizing the normal operating condition and the abnormally operative condition relative to a predetermined range of current consumption.

18. A method as defined in claim 17, further comprising:

sensing an amount of current consumption greater than the predetermined range of current consumption to recognize the abnormally operative condition.

19. A method as defined in claim 17, further comprising:

sensing an amount of current consumption less than the predetermined range of current consumption to recognize the abnormally operative condition.

20. A method as defined in claim 16, further comprising:

recognizing the normal operative condition and the inoperative condition relative to a predetermined range of voltage of the power supplied to the terminal adapter.

21. A method as defined in claim 13, further comprising:

disconnecting the active branch circuit when substituting the termination impedance.

22. A method as defined in claim 13, further comprising:

using a predetermined impedance value for the termination impedance to minimize return loss.

23. A method as defined in claim 13, wherein the cable television network includes coaxial cables having a predetermined characteristic impedance value, and further comprising:

connecting the coaxial cables having the predetermined characteristic impedance value to the passive and active branch circuits of the terminal adapter; and

using an impedance value for the termination impedance which is substantially equal to a predetermined characteristic impedance value of the coaxial cables.

24. A method as defined in claim 13, further comprising:

using a predetermined impedance value for the termination impedance which is selected to minimize signal reflections into the cable television network.