ELFWork Scrapbook
Cable Television
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Cable Television
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Cable television systems are typically built under power lines on the same poles. This picture shows a congested pole with multiple cables, taps, and customer drops. Bonding and grounding, including interutility bonding, becomes a complicated matter when non-standard, specialized procedures are required. | |
| The cable television isolator, shown here housed in a plastic enclosure at the residence drop point, provides DC and low-frequency AC electrical isolation between the cable plant and the residential cable system. The RF signal that provides the cable service passes through the device unaffected. | |
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The initial work to develop a low-frequency cable television
isolator that did not affect the RF operation led to the device
on the left.
This design was subject to ingress interference,
a problem that can cause multiple pictures on the TV.
A broadcast signal intense enough can penetrate into the cable
system through the metallic discontinuity necessary to
achieve the AC isolation in in the outside shell.
The device on the right solves the problem. Developed by Zenith, it is currently manufactured and sold by Telesignal Communications in England. |
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` Last updated: June 5, 1998. |