Constant input port impedance for CATV amplifier with passive modem port

• US 7,974,586 B2
• Filed: 09/14/2007
• Issued: 07/05/2011
• Est. Priority Date: 09/14/2007
• Status: Active Grant

• Current Assignee: Times Fiber Communications Incorporated (Amphenol Corporation)
• Original Assignee: Extreme Broadband Engineering LLC
• Inventors: Shapson, Jay F., Romerein, Robert L.
• Primary Examiner(s): LEE, JOHN J
• Application Number:
  US11/900,988
• Publication Number:
  US 20090077608A1
• Time in Patent Office: 1,390 Days
• Field of Search: 455/82, 455/572, 455/127.1, 455/83, 455/78, 455/127.3, 455/14, 455/15, 455/73, 455/79, 455/194.2, 455/273, 455/275, 455/277.1, 455/341, 725/127, 725/149, 725/126, 725/125, 725/121, 330/100, 327/108
• US Class Current: 455/78
• CPC Class Codes: H03H 7/463 Duplexers
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• 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

Abstract

A passive directional coupler is receptive of VoIP, Internet, and video/data signals, and is used in a CATV amplifier device to couple the video/data signals from a cable drop input port to the input terminal of an amplifier, and to passively bypass the VoIP and Internet signals to a modem port, for insuring continuous connection of the VoIP and Internet signals to the a modem of a user connected to the modem port, regardless of the loss of power to the amplifier or the failure of the amplifier, in one embodiment of the invention. In another embodiment, a switching circuit is responsive to the loss of power to the amplifier, for electrically connecting a 75 ohm resistor between a source of reference potential, and the common connection between the directional coupler and the amplifier, for maintaining a 75 ohm impedance at the directional coupler output to the common connection. In a preferred embodiment, the switching circuit also opens the common connection between the directional coupler and amplifier, upon the loss of power to the amplifier.

Claims

1. An amplifier device for a cable antenna television system comprising:

an amplifier for amplifying video/data signals having an input terminal, an output terminal, and a power terminal;

at least a first video/data output port coupled to the output terminal of said amplifier;

a cable drop input terminal for receiving VoIP, Internet, video and data signals;

a power port for receiving a source of voltage, said power port being coupled to the power terminal of said amplifier;

a source of reference potential;

a modem port for connection to the modem of a user;

a directional coupler having an input terminal connected to said cable drop input terminal, a first output terminal for outputting said VoIP and Internet signals to the modem port, and a second output terminal for outputting video and data signals to the input terminal of said amplifier;

a 75 ohm resistor having a free end, and another end connected to the common connection between said directional coupler and said amplifier; and

switching circuit means responsive to the loss of power or voltage to said amplifier, for electrically connecting the free end of said resistor to said source of reference potential.

2. The amplifier device of claim 1, wherein said switching circuit means further includes means responsive to the loss of power or voltage to said amplifier for disconnecting said amplifier from its common connection with said directional coupler.

3. The amplifier device of claim 1, further including:

second and third video/data output ports; and

a splitter having an input connected to said output terminal of said amplifier, and first through third output terminals connected to said first through third video/data output ports, respectively, for providing amplified video/data signals thereto.

4. The amplifier device of claim 3, further including:

a first forward biased diode connected between said power port and said power terminal;

an inductor for blocking high frequency signals; and

a second forward biased diode connected in series with said inductor between said modem port and said power terminal.

5. The amplifier device of claim 1, further including:

a first forward biased diode connected between said power port and said power terminal;

an inductor for blocking high frequency signals; and

a second forward biased diode connected in series with said inductor between said modem port and said power terminal.

6. The amplifier device of claim 1, further including:

second through eighth video/data output ports; and

a splitter having an input connected to said output terminal of said amplifier, and first through eighth video/data output terminals connected to said first through eighth video/data output ports, respectively, for providing amplified video/data signals thereto.

7. The amplifier device of claim 6, further including:

a first forward biased diode connected between said power port and said power terminal;

an inductor for blocking high frequency signals; and

a second forward biased diode connected in series with said inductor between said modem port and said power terminal.

8. An amplifier device for a cable antenna television system comprising:

an amplifier for amplifying video/data signals having an input terminal, an output terminal, and a power terminal;

a plurality of video/data output ports coupled to the output terminal of said amplifier;

a cable drop input terminal for receiving VoIP, Internet, video and data signals;

a power port for receiving a source of voltage, said power port being coupled to the power terminal of said amplifier;

a source of reference potential;

a modem port for connection to the modem of a user;

a directional coupler having an input terminal connected to said cable drop input terminal, a first output terminal connected for outputting said VoIP and Internet signals to the modem port, and a second output terminal connected for outputting video and data signals to the input terminal of said amplifier;

a 75 ohm resistor having one end connected to the common connection of the second output terminal of said directional coupler and the input terminal of said amplifier, said resistor having a free end; and

switching means connected between the free end of said resistor and said source of reference potential, responsive to the loss of power or voltage to said amplifier, for electrically connecting the free end of said resistor to said source of reference potential.

9. The amplifier device of claim 8, wherein said switching means further includes means responsive to the loss of power or voltage to said amplifier for disconnecting said amplifier from the second output terminal of said directional coupler.

10. The amplifier device of claim 8, further including:

a splitter having an input terminal connected to the output terminal of said amplifier, and a plurality of output terminals connected to the plurality of video/data output ports, respectively, for coupling amplified video/data signals thereto.

11. The amplifier device of claim 10, further including:

a first forward biased diode connected between said power port and said power terminal;

an inductor for blocking high frequency signals; and

a second forward biased diode connected in series with said inductor between said modem port and said power terminal.

12. The amplifier of claim 10, wherein said directional coupler is passive.

13. The amplifier of claim 12, wherein said splitter is passive.

14. The amplifier of claim 10, wherein said splitter is passive.

15. The amplifier of claim 14, wherein said directional coupler is passive.

16. The amplifier device of claim 8, further including:

a first forward biased diode connected between said power port and said power terminal;

an inductor for blocking high frequency signals; and

a second forward biased diode connected in series with said inductor between said modem port and said power terminal.

17. The amplifier device of claim 8, wherein said directional coupler is passive.

18. An amplifier device comprising:

an input port for connection to a cable drop;

a directional coupler connected between said input port and a modem port;

an amplifier having an input and an output;

normally open switching means coupled between said directional coupler and the input of said amplifier;

a resistor having a free end, and another end connected to a common connection between said directional coupler, and said normally open switching means;

a source of reference potential;

normally closed switching means connected between the free end of said resistor and said source of reference potential;

a power port for receiving a source of electrical power for said amplifier;

said normally open switching being responsive to the application of power to said amplifier for closing to electrically connect said directional coupler to the input of said amplifier; and

said normally closed switching means being responsive to the application of power to said amplifier for opening to disconnect an electrical connection between the free end of said resistor and said source of reference potential.

19. The amplifier device of claim 18, wherein said resistor has a value of 75 ohms.

20. A CATV amplifier device comprising:

an amplifier having an input terminal and an output terminal;

a source of reference potential;

a power port for receiving power for said amplifier;

a resistor having one end connected to said source of reference potential, and another end; and

switching means having a first terminal for receiving video/data signals, a second terminal electrically connected to the input of said amplifier, and a third terminal electrically connected to the another end of said resistor, said switching means being responsive to the application of power to said amplifier for electrically connecting said first and second terminals together, and further being responsive to the loss of power to said amplifier for both removing the electrical connection between said first and second terminals, and for electrically connecting said first and third terminals together.

21. The amplifier device of claim 20, wherein said switching means consists of an electromechanical relay.

22. The amplifier device of claim 20, wherein said switching means consists of a solid-state switching circuit.

23. The amplifier device of claim 20, further including:

at least one video/data port;

a first diplex filter having an input terminal for receiving video/data signals, a low band terminal for low band video/data signals, and a high band terminal for high band video/data signals, said high band terminal being electrically connected to said first terminal of said switching means;

a second diplex filter having a high band terminal electrically connected to the output terminal of said amplifier, a low band terminal electrically coupled to the low band terminal of said first diplex filter, and an output terminal electrically coupled to said at least one video/data port.

24. The amplifier device of claim 20, wherein said amplifier is a bidirectional or forward/reverse amplifier.

25. A CATV amplifier device comprising at least one video/data port;

a first amplifier having an input terminal receptive of high band video/data signals, and an output terminal;

a second amplifier having an input terminal receptive of low band video/data signals, and an output terminal;

a first diplex filter having an input terminal electrically connected to said at least one video/data port, a low band terminal for low band video/data signals electrically connected to the input terminal of said second amplifier, and a high band terminal for high band video/data signals electrically connected to the output of said first amplifier;

a source of reference potential;

a power port for receiving electrical power for coupling to said first and second amplifiers;

a second diplex filter having an input terminal for receiving video/data signals, a low band terminal, and a high band terminal;

first switching circuit means including a resistor having one end connected to said source of reference potential, and another end, said first switching circuit mans being responsive to the application of power to said first amplifier, for electrically coupling the high band terminal of said second diplex filter to the input terminal of said first amplifier, and responsive to the loss of power to said first amplifier for both electrically decoupling said high band terminal of said second diplex filter from said first amplifier, and electrically coupling the another end of said resistor to the high band terminal of said second diplex; and

second switching circuit means including a resistor having one end connected to said source of reference potential, and another end, said second switching circuit means being responsive either to the application of power to said second amplifier for electrically coupling the low band terminal of said second diplex filter to the output terminal of said second amplifier, or to the loss of power to said second amplifier for decoupling its output terminal from said diplex filter, and electrically coupling the another end of said resistor to the low band terminal of said second diplex filter.

26. An amplifier system for a cable antenna television system comprising:

an amplifier for amplifying video/data signals having an input terminal, an output terminal, and a power terminal;

a cable drop input terminal for receiving VoIP, Internet, video and data signals;

circuit means for electrically coupling said cable drop input terminal to said input terminal of said amplifier;

a power port for receiving a source of voltage, said power port being coupled to the power terminal of said amplifier;

a source of reference potential;

a resistor having a free end, and another end coupled to said cable drop input terminal; and

said circuit means including switching means responsive to the loss of power or voltage to said amplifier, for electrically connecting the free end of said resistor to said source of reference potential, for maintaining a constant input impedance at said cable drop input terminal.

27. The amplifier device of claim 26, wherein said switching means further includes means responsive to the loss of power or voltage to said amplifier for disconnecting the input terminal of said amplifier from said cable drop input terminal.

28. A CATV amplifier system comprising:

an input terminal for receiving RF signals;

an amplifier including an input terminal, output terminal, and power terminal;

a source of power connected to said power terminal of said amplifier;

a source of reference potential;

a resistor having one end connected to said source of reference potential, and another end;

switching means both responsive to the application of power to said amplifier for connecting the input terminal of said amplifier to said signal input terminal, and to the loss of power to said amplifier for substantially simultaneously disconnecting said amplifier from said signal input terminal and connecting said another end of said resistor to said input terminal.