sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring Cable TV backbone design for high rise

Hi All, I have just been tasked with designing a backbone for cable TV for a high rise building. 22 stories. I plan on running (1) RG11 to every other floor. Each floor has approximately 8 residential units. From the IDF on every other floor I plan to run (1) RG6QS to a media box in each unit and from there RG6QS to the individual drop locations. Each unit will have approximately 4 RG6QS drops. So worst case scenario if all the drops were live we would be looking at serving 64 locations from (1) RG11. So to summarize I would have (1) RG11 to the each IDF, (1) 16 way splitter RG11 to RG6 in the IDF, (1) RG6 home run to each units media box and then each unit will have (1) 4-6 way splitter with 4-6 drops per unit. Not having much experience with RG11 or cable TV my questions are:
Is this design viable? Am I splitting the cable too many times? Is one RG11 to each IDF going to be able to serve up to 64 connections? How many locations/drops can I get out of (1) RG11? I have one IDF that will be serving a possible 96 drops. Would I need more RG11 drops to this IDF? We are not providing any electronics but simply providing the infrastructure. Hopefully this makes sense. Looking to see if this design is correct and if not would appreciate any suggestions to correct. Thank you all very much for your input. Cheers, Velcro

Do you have ANY experience and education in CATV? Sorry Charlie, one word- NO! Sub it out to somebody who knows what they are doing or turn it down.

If you have been around here for a while you should know that I'm adamant about techs knowing their limitations and acting professional. CATV is much more complex than you realize and by what you say I can tell right away this is not something that you know anything about and should be doing.

I can't believe anybody in their right mind would be so naive to think that they could ask somebody who was not affiliated with the cable company and who has zero experience to handle a job of this magnitude. Have they even approached the cable company to see if they will wire the building at no cost? Most will if they will have enough subscribers. I know because that's what I used to do.

No offence, just the way it is.

-Hal

Understood. Thanks.

Years ago I did a lot of work at Time & Life's Headquarters Building in Rockefeller Center in NYC. When CNN was moving in I was the foreman responsible for (among other things) the Video.

The work was on several floors scattered throughout the complex and included the new studios for Connie Chung and Paula Zahn. (Both great, down-to-earth ladies BTW)There was a video engineering firm that was responsible for the design of the video system. I worked for the Electrical Contractor.

Besides the major work in the studios, every desk had two screened Cat 6 cables (one each for Voice and Data) and an RG-6 for Video. There were a LOT of drops. I don't remember the exact amount but it was in the hundreds.

Besides the fiber feeds for the studios, most of the job seemed to be RG-11 feeding RG-6 drops. Most, but not all. In some places we had larger cable (RG-8 think, but I can't remember) and in some places we had amplifiers installed in the middle of the runs.

I asked the engineer from the design company about these aberrations to the standard install and he said that if we had installed straight RG-11 we'd have troubles up the wazoo. I installed the job as designed and when it cut over the picture was terrible.

Then I dragged a monitor over to the Time Warner feed coming in and IT was terrible. TW fixed the feed and the picture was immaculate - everywhere.

I'd like to take some credit for a good install, but the credit for the quality belonged to the design engineers who knew when to put in bigger cable, when to put in smaller cable, when to boost the signal and what equipment to use.

If I can quote an early figure from my childhood:

"Don't try this at home boys and girls."

Like Hal said, if you don't know how, don't do it.

Sam

Good advice SS. I'll let you know what happens.

Good luck. I have to say - there's nothing as humbling as working with a real engineer.

I've done some very large jobs over the past 40+ years in the industry and some of them have been designed by top flight people. I've been the guy responsible for making their plans work - but it's been their plans.

I always look at the plans when I'm starting a job and think about how I would have designed it and then compare. Some times I'm on the money and sometimes I realize just how little I know.

I did the PA work at JFK airport for AA some years ago. Thousands and thousands of speakers. Hundreds and hundreds of amplifiers. You look at the job layout and go: Why do that here? What was the point of that?

Then when you hear/see/experience the results you understand.

Sometimes I think that jobs have been "overbuilt" - but I'd rather have the job overbuilt then under built - any day.

Sam

Thanks SS. I'm going on 15 years in the biz in various roles and one of my good/bad characteristics is that I can't stand being told that I can't do something or that it can't be done. So here I am on a Sunday doing my research because I am determined to figure this out and do it right! And you can bet I will. I hesitated before posting knowing that I may get rebuffed....oh well. I understand. Luckily we have great manufacturer support and I will engage their engineers and win this deal!! Cheers!

Even on commercial buildings with far fewer drop counts (max 200), all we do is pull in the RG6 from each drop to an IDF, mark it, and trim out the cable at the wallplate. The cable/satellite company does the rest. Every cable is homerun to a closet, absolutely no splitters - ever.

Speccing the taps, feeds, etc. is not something I do because a) I don't know how and b) even if I did know how, I don't have to right tools to tune/test/troubleshoot a CATV system.

What I do is about the extent of what would meet with Hal's approval, though he's said before 'don't do anything with CATV except run cable', or words to that effect. And, he's right.

"Is this design viable?"; I don't know, but I take it by Hal's reply that it isn't. Even if it were, I'd be curious to know how you plan(ned) to install a 4-6 way splitter in each unit.

Can you do this job? I'm sure that with the correct training and tools, you could do it.

Should you do this job? imho, no.
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It may be the type of buildings I cable (more likely my limited experience), but only once have I seen the cable company completely cable a building. Some companies will give us the cable to use, but many don't even do that.

Jack

... one of my good/bad characteristics is that I can't stand being told that I can't do something or that it can't be done.

To me that is a rather immature and childish attitude but I wish you luck my friend. Unfortunately we can't help you here.

-Hal

All I can say is listen to Hal. His wisdom speaks volumes.