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Patent EP0549129A1 successfully refreshed from Google Patents.
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EP0549129A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Feeder switch for a bidirectional cable television system

Assignee: AT&T Inc
•
Filing: 1992-11-23
•
Granted: —
•
Expires: 2012-11-23
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Abstract

Abstract A two-way cable television (CATV) system includes a cable for transmitting television signals downstream, from a headend (connected to port 50) to a subscriber, (connected to port 10 for example) in the VHF frequency band, and for transmitting signals upstream, from the subscriber to the headend, in the frequency band below VHF. A feeder switch (50) is series-connected with the cable through a pair of input/output ports (10,50). These ports are normally interconnected by a high pass filter (510) to preclude the transmission of electrical signals in the upstream frequency band. However, circuitry (520,530,550) within the feeder switch detects upstream transmission and, in response, replaces the high pass filter with a direct connection (580) between the ports to enable both upstream and downstream transmission. Since each subscriber is connected to the cable via the feeder switch, thermal noise does not accumulate in the upstream direction from subscribers (most of them) who are not presently transmitting.

Inventors

  • 👤 Lowell Gene Atkinson
  • 👤 Ronald Lee Katz

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-05 04:13
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/16; H04N7/173; H04N7/17309; H04N7/17318

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 191 words
A bidirectional cable television distribution system comprising a headend (10) for transmitting television signals downstream in a first frequency band to one or more subscriber stations over a cable (200), and simultaneously receiving television signals in a second frequency band that are transmitted upstream by one of the subscriber stations (30) over the cable, said cable including feeder apparatus (500) which is series-connected between the headend and said one of the subscriber stations, the feeder apparatus including a first port (B) for interconnection with the headend and a second port (A) for interconnection with the station, the feeder apparatus CHARACTERIZED BY: filter means (510), interconnected between the first and second ports, for simultaneously enabling the transmission of signals in the first frequency band while precluding the transmission of signals in the second frequency band; and switching means (520, 530, 550, 570, 580), responsive to a predetermined control signal received by the feeder apparatus, for enabling the transmission of signals in the second frequency band between the first and second ports; whereby the feeder apparatus precludes upstream transmission of noise in the second frequency band unless it receives the predetermined control signal.
Claim 2
Dependent Claim 17 words
The cable distribution system of claim 1 wherein the filter means (510) comprises a high pass filter.
Claim 3
Dependent Claim 52 words
The cable distribution system of claim 3 wherein the switching means (520, 530, 550, 570, 580) includes means (550) for detecting a signal generated by said one subscriber station (30); and means (580) for effectively shunting the high pass filter with a low impedance path for frequencies in the second frequency band.
Claim 4
Dependent Claim 18 words
The cable distribution system of claim 3 wherein said low impedance path substantially comprises a direct connection (580).
Claim 5
Dependent Claim 20 words
The cable distribution system of claim 2 wherein the first frequency band substantially extends between 50 MHz and 450 MHz.
Claim 6
Dependent Claim 20 words
The cable distribution system of claim 3 wherein the second frequency band substantially extends between 5 MHz and 37 MHz.

References Cited (Backward Citations)

US3886454A Cited
US3924187A Cited

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