Return path filter
DCFirst Claim
1. An apparatus for controlling the return path loss in a two-way communication system, said apparatus comprising:
- an input terminal and an output terminal;
forward path filter means, coupled to said input and said output terminals, for passing signals in a forward path frequency band of the communication system, said forward path filter means including a resonant circuit component; and
return path filter means, coupled to said input and said output terminals, for passing signals in a return path frequency band of the communication system, said return path filter means including a resonant circuit which is coupled to the resonant circuit component of said forward path filter means,a combined resonant circuit being formed, at least in part, by the resonant circuit of said return path filter means and the resonant circuit component of said forward path filter means,said return path filter means further including attenuator means for attenuating the signals in the return path frequency band as they pass through said return path filter means.
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Accused Products
Abstract
A filter for controlling the return path loss in a multi-channel communication system having forward and return paths. The filter comprises a forward path filter network, and a return path filter network. The forward path network passes signals in the forward path, and includes at least one resonant circuit component, such as a capacitor, which is coupled to the return path network. The return path network passes signals in the return path, and includes at least one resonant circuit, such as a series LC trap to ground. A combined resonant circuit is formed, at least in part, by the resonant circuit of the return path network and the resonant circuit component of the forward path network (e.g., a combined series LC trap to ground). The return path network further includes an attenuator network which is designed to attenuate the signals in the return path frequency band. Preferably, the attenuator network is a resistive network which provides a predetermined amount of flat loss.
95 Citations
42 Claims
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1. An apparatus for controlling the return path loss in a two-way communication system, said apparatus comprising:
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an input terminal and an output terminal; forward path filter means, coupled to said input and said output terminals, for passing signals in a forward path frequency band of the communication system, said forward path filter means including a resonant circuit component; and return path filter means, coupled to said input and said output terminals, for passing signals in a return path frequency band of the communication system, said return path filter means including a resonant circuit which is coupled to the resonant circuit component of said forward path filter means, a combined resonant circuit being formed, at least in part, by the resonant circuit of said return path filter means and the resonant circuit component of said forward path filter means, said return path filter means further including attenuator means for attenuating the signals in the return path frequency band as they pass through said return path filter means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A passive filter for controlling the return path loss in a communication system having a forward path and a return path, said filter comprising:
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a housing having an interior volume of less than about 5 cubic inches; a first terminal and a second terminal; a first passive filter network, mounted inside said housing and coupled to said first and said second terminals and to ground, said first filter network having a passband which passes signals in the forward path of the communication system and a stop band which attenuates signals in the return path of the communication system; a second passive filter network, mounted inside said housing and coupled to said first and said second terminals and to ground, said second filter network having a passband which passes signals in the return path of the communication system and a stop band which attenuates signals in the forward path of the communication system, said second filter network further including a passive attenuator network which attenuates signals in the return path of the communication system as the signals pass through said second filter network. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. An apparatus for controlling the return path loss in a communication system having a forward path and a return path, said apparatus comprising:
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a windowed highpass filter having a highpass passband which passes signals in the forward path and a bandpass passband or window which passes signals in the return path; and attenuator means, coupled to said windowed highpass filter, for attenuating the window of said windowed highpass filter by a predetermined amount, such that the signals passing through the window are attenuated thereby. - View Dependent Claims (30, 31, 32, 33, 34)
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35. A method of controlling the return path loss in a communication system having a forward path and a return path, said method comprising the steps of:
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(a) passing signals in the forward path of the communication system through a highpass filter passband; (b) passing signals in the return path of the communication system through a bandpass filter passband or window; and (c) attenuating the window by a predetermined amount such that the signals passing through the window are attenuated thereby.
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36. The method as recited in 35, wherein the communication system is a cable television system having a headend and a subscriber end, and wherein
said step (a) includes passing RF television programming signals transmitted from the headend through said highpass filter passband; - and
said step (b) includes passing signals transmitted from the subscriber end through said window.
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37. The method as recited in 35, wherein said step (c) includes attenuating the window by 6 dB.
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38. The method as recited in 35, wherein said step (c) includes attenuating the window by 12 dB.
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39. A passive filter for controlling the return path loss in a communication system having a forward path and a return path, said passive filter comprising:
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a housing having an interior volume of less than about 5 cubic inches; a first terminal and a second terminal; a passive filter network, mounted inside said housing and coupled to said first and said second terminals and to ground, said filter network having a first passband which passes signals in the forward path and a second passband which passes signals in the return path, said filter network including a passive attenuator circuit, associated with the second passband, which attenuates signals in the return path by a predetermined amount as the signals pass through the second passband of said filter network. - View Dependent Claims (40, 41, 42)
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Specification