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Re: cso/ctb testing

First understand how these CSO/CTB beats are created. Each anolog channel from Ch2 on produse harmonics of themselves. Example Ch2 @ 55.25 will create another small beat at 110.50..55.25+55.25=110.50 and so on. Some of these beats fall behind a video carrier. In order to measure these carriers correctly, the video carrier under test needs to be removed at the headend so the beat under the carrier is visable to measure. There is no need to turn off all the channels in the system, just the carrier under testing. This would be the maunel way of testing CSO/CTB, for lack of a better disciption.
With today's CATV services, the industry moved toward being lease intrusive to their customers and started testing CSO/CTB using the Gating option on testing equipment. Which is what the SDA does by using math beyond myself to understand. However is will estimate the results to give you a CSO/CTB measurement.
In the day when amps went 10 to 50 amps in cascade this became important to measure and maintain. With today's design which tend to be less then 5 amps in cascade it became less a issue and over looked as not that important. Which should not be the case.

So to some it up, the best way to test is removing the carrier and get a solid number on the longest cascade at a EOL with a 100' drop. Good luck
This is CABL.com posting #350706. Tiny Link: cabl.co/mbDoI
Posted in reply to: Re: cso/ctb testing by massive coax
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