What Happens If the Digital Cable Length is too Long?

by Pat Brown

In this article, Pat Brown addresses an issue that occurs if the digital cable length is too long.

This happened just after the recent SynAudCon Digital seminar. Digital audio training includes a presentation of guidelines for allowable length of coaxial cable. A general guideline for allowable cable length for some professional interfaces is 100 m (330 ft). If the cable is too long, the signal can be degraded, causing errors. The data must then be resent, which slows down the connection.

Digital Cable TV

We had a length issue with our cable TV/Internet at the house, so 18 months ago the cable company installed a low-loss coaxial cable, with a junction box half-way between the house and road. After the installation, there was a “temporary feed” from the main drop to the junction box that they left laying on top of the ground. It would be buried at a later date. Surprisingly, there was NO improvement in speed due to the new cable. I’ve been mowing around it for a year and a half!

A Dead Cable Modem

Our cable modem died this past Thursday and the tech arrived to replace it on Friday. We walked down and looked at the buried cable situation. After sizing it up, he figured out that the crew of 18 months ago installed the new junction box in the yard correctly, but then ran a cable on top of the ground, back down to the road, and tied into the original cable feeding the house. So, rather than REDUCE the line loss, they actually added several hundred MORE feet. He was amazed that it worked at all.
This is an example of how through incompetence, much money can be spent to make something worse. The cable company has agreed to re-install it, and the yard is already marked for the cable burial. I’ll be watching this time with my fingers crossed.  pb
Digital Cable Length - Diagram showing how the cable was buried

Click to enlarge