Module for a cable TV network distribution tap

Abstract

There is provided a module for a cable TV network distribution tap comprising an insert (42) locatable over a power pass bar (24) and an activation switch (26) located in a cable television network distribution tap back box (e.g. a Cisco / Scientific Atlanta back box) and at least one support element (52) mounted on the insert and moveable to locate at least part of the support element beneath the power pass bar. When a faceplate is mounted on the box, the pivot axis of the power pass bar is changed to ensure the bar does not physically contact connectors on which terminals are mounted. An air gap between the bar and connector support blocks produces a lower capacitive coupling and ensures the operational frequency of the box can be extended above 1.2 GHz without removal of the box from the CATV network. The support element may be rotatable by 90 degrees between a first position parallel to the power pass bar and a second position where a part of the element is beneath the bar. The insert may comprise a channel receiving the bar and an aperture receiving an activation switch, and may comprise stop regions to limit element movement.

Description

A Cisco / Scientific Atlanta back box 10 is shown in Figure 1 and comprises back box housing 12 with network input connection 14 and network output connection 16, connector terminals 20, 20’ each surrounded by a respective plastics connector support block 22, 22’, power pass bar 24 extending between connector terminals 20, 20’ and an actuator switch 26 for disconnecting power pass bar 24 from connector terminals 20, 20’ when a faceplate is mounted on back box 10. Channel 30 extends between connector support blocks 22, 22’and has a central groove 32, see Figure 2, to receive power pass bar 24 when it is deflected downwards by actuator switch 26 and disconnected. In distribution taps, the operational bandwidth above 1.2GHz is limited due to coupling between the connector blocks and the power bypass bar. This is significant on a Cisco / SA back box because when a faceplate is fitted and actuator switch 26 activated, power pass bar 24 slides downwards into groove 32 but remains in physical contact with connector support blocks 22, 22’ in region 34, see Figure 2. This results in a high capacitive coupling between connector terminals 20, 20’ and the disconnected power pass bar 24 and limits the operational frequency of a Cisco / SA back box to below 1 2GHz. To resolve this issue and as shown in Figures 3 and 4, an add-on module 40 is provided that clips onto the existing MBB assembly of power pass bar 24 and actuator switch 26 to alter the pivot point of axis of bar 24 to enable increased operational bandwidth without causing disruption to the system power. Module 40 comprises a substantially rectangular insert, typically moulded from plastics material, with a central square aperture 44 and configured such that module 40t locates over existing actuator switch 26 and sits within channel 30. Insert 42 is formed with a channel 46 on its lower face which receives power pass bar 24, see Figure 5. Insert 42 is also formed with a vertical channel 50, 50’ proximal each end, these two channels each receiving a lever support arm 52. Prior to insertion of module 40 into channel 30, lever support arms 52 are positioned parallel to internal channel 46 so as to avoid obstructing internal channel 46. When in use, module 40 is placed over actuation switch 26 so as to lie within channel 30 and lever arms 52 are positioned as shown in Figure 3. Lever arms 52 are then rotated inwards by 90 degrees to the position shown in Figures 4 and 5 so as to be proximal to bar 24. Stop regions 54, 56 formed within insert 42 define how far lever arms 52 can rotate and limit rotation to 90 degrees. Indicia 57 and / or a groove 58 moulded into insert 42 can be used to visually indicate the correct position of lever arms 52. When a faceplate is fitted onto back box 10 with module 40 in position, actuation switch 26 is depressed by the faceplate to break the terminal connection as shown in Figure 6. Bar 24 deflects downwards in response to switch 26 but the positioning of lever arms 52 changes the pivot axis of bar 24 ensuring the ends of power pass bar 24 are levered away from connector support blocks 22, 22’ such that there is no physical contact between power pass bar 24 and connector support blocks 22, 22’. There is 5 thus an air gap between power pass bar 24 and connector support blocks 22, 22’, producing a lower capacitive coupling and ensuring the operational frequency of a Cisco / SA back box can be extended above 1.2GHz without physically removing the back box from the CATV network. This enables the installer to upgrade the operational frequency of the network infrastructure without signal and power io disruption compared to full tap replacement.

Claims

1. A module for a cable TV network distribution tap comprising an insert locatable over a power pass bar and an activation switch located in a Cisco / Scientific Atlanta back box and at least one support element mounted on the insert and moveable to locate at least part of the at least one support element beneath the power pass bar.

2. A module according to Claim 1, wherein the at least one support element is rotatable by 90 degrees between a first position parallel to the power pass bar and a second position where at least part of the at least one support element is beneath the power pass bar.

3. A module according to Claim 1 or Claim 2, wherein the insert comprises a channel to receive the power pass bar and an aperture to receive an activation switch.

4. A module according to any of the preceding claims, wherein the insert further comprises stop regions to limit movement of the at least one support element.

5. A module according to any of the preceding claims, where two support elements are mounted proximal opposing ends of the insert.

6. A Cisco / Scientific Atlanta back box incorporating a module according to any of the preceding claims.

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