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Jose and Dave, I have attached a doc with a quick overview of the layout of the typical cable TV spectrum (USA). Might be helpful to those interested. I have also attached a doc on measuring the 256 QAM carriers in such a system with the TinySA.?
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The cable spectrum is fairly consistent in general layout, the complexity exists in the allocation of EIA's (channels) into dedicated service bands, and the embedding of programming in each of the carriers. However, as this is done through centralized digital network programming it is not apparent to someone observing the spectrum on an analyzer.? Normally the only programming data available to the customer (or outside observer) is the listing of program channels as tuned by the digital set top box. Tables of programming maps to the individual carriers, as well as dedicated band assignments are only available to the systems technical personnel.?? There are a myriad of issues that affect cable transmission, ingress of interference, response over such a wide bandwidth, transmission delays, reflections, variation with temperature etc. it's a wonder the systems work as well as they do given hundreds of miles of plant and thousands of connections in a typical system. ?? ----------------------------------------- From: "DAVE REISER"To: "[email protected]" Cc: Sent: Monday October 4 2021 7:02:12PM Subject: Re: [tinysa] Uhf TV monitoring, Antenna testing I would be interested in seeing one.? Here is the raw data to make one.? In the QAM column, each channel can have 10 or more 6 MHz channels compressed into one QAM 6 MHz channel.? Also channel numbers don¡¯t follow.? ??For example, if I want to watch channel 975 my set-top converter will tune to channel 121.? That¡¯s totally up to the cable company. ? Kind Regards, Dave Dave Reiser Phone: 301-216-5394 Mobile: 301-802-1929 Email:? davereiser2outlook.com 520 Russell Avenue, Gaithersburg, MD 20877 ? From: [email protected]
<[email protected]> On Behalf Of Jose Cruz
Sent: Monday, October 4, 2021 3:10 PM To: [email protected] Subject: Re: [tinysa] Uhf TV monitoring, Antenna testing ? Is there some type of overlay to see the Tv
channels portion of the spectrum? |
