In Reply to: Re: Ground Breaker and digital cable. posted by Steve K on November 24, 2002 at 12:40:34:
Well, I couldn't resist joining in on this topic. First off, I am a CATV technician. I have been to numerous schools and deal with EVERY part of the RF/Fiber plant of the CATV system. Don't assume all CATV installers or techs are "dunces". 90% of all noise problems are generated by the customers VCR, TV, or bad jumper wires (most with push on ends) I have NEVER seen noise caused by an improper or non existing ground. The primary reason for grounding the cable at the point that it enters the house is for electrical protection. Proper grounding is grounding the splitter or protetctor within 20 feet or less of the POWER ground. The differnce in the two grounds can be a problem, NOT with noise. The problem comes into play when the cable has a good ground and the house has a poor ground or no ground. If the house were to loose the neutral connection with the power line, it will use the cable drop as the house ground. This can be very dangerous. This is why we ground to the house power ground. There is 15 dbmv differnce between the audio carrier and the video carrier in an analog channel within the 6 mhz of bandwith that it takes up. The digital is converted from digital to analog via the convertor box and the same is true whith its levels. This is why bad connectors and jumper wires are the culpruts of many a audio problem. Voltage on the line typically shows up on the tv screen as rolling horizontal lines or "hum bars" These usually start at the bottom and work their way up the screen. Usually there will be 2 bars on the screen at any given time, this is due to the fact that power is 60hz, and the tv scans each half at 30hz and then combines them.
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Follow Ups
- Re: Ground Breaker and digital cable. - billwilljr 20:35:03 12/11/02 (0)