I am building a small RV park that has only 10 spaces. I am thinking about running Coax cable to each spot to provide TV service. At first I will just be hooking it up to broadcast tv using an antenna, but may provide cable tv eventually.

Would it be ok to just daisy chain all 10 spots? Or possibly even just 5 spots on 2 separate lines? I would just run direct burial grade coax from the office to spot 1, use a splitter to run another cable to spot 2, and so on.

I am mainly wondering if there will be any issues with signal quality degrading too much after each split? Has anybody done anything similar to this? This cable will be transmitting HD tv only, no internet. There is a driveway up the middle of the park with 5 spaces on either side, with the office right in the middle on one side of the driveway. The spaces are each about 40 ft apart from one another.

closed as off-topic by mmathis, Daniel Griscom, Tester101 Aug 28 '17 at 14:11

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  • How strong of a signal do you get now? Splitting a signal always degrades it somewhat; whether that's significant depends on how strong the original signal is and how many times it's split. – mmathis Aug 22 '17 at 15:47
  • You're likely going to need to at least RG11 (much heavier than RG6) and you will likely need a "better than typical home grade" amplifier. This project is not easy, it's also not DIY home improvement. – Tyson Aug 22 '17 at 16:30
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    I doaintenance for 2 large RV parks on occasion. Every RV comes equipped with it's own tv capabilities, whether satellite or antenna, no matter what the age. Wifi is where it's at now. – NPM Aug 22 '17 at 16:35
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    @NPM well that is good information to know too, so you are saying not many people even use it since they have built in options available? Maybe installing cable is not worth the effort if people don't use it much anymore... – lucky.expert Aug 22 '17 at 18:06
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    I'm voting to close this question as off-topic because it's a commercial project, not home improvement – mmathis Aug 22 '17 at 19:07

If your system is analog and not digital, the following will apply. If it is digital video transmission, it's out of my league.

Analog cable television systems transmit radio frequencies into coaxial cable (simplified explanation) which has signal loss over distance. The lower frequencies (lower numbered channels) will decrease strength at a lower rate than the higher frequencies.

Smaller diameter cable will have greater loss than larger diameter cable. If you can use RG-8U for the "backbone" of the system, it's superior to the smaller RG-6U typically used for house drops and internal wiring.

If you use splitters at each junction, you'll have a fraction of signal level at the end. There are devices known as directional couplers which are similar in concept to splitters, but smarter! The construction of these devices are such that there is an "in," an "out," and a "tap," although the terminology for the last may vary from manufacturer to manufacturer.

The operation is such that, for example, you would have 34 db signal level at the "in" on a 26 db directional coupler. It would provide 8 db signal level to the tap port and pass along the rest of the signal to the "out" port. The signal level would not be reduced by 8 db, but there is some loss involved. In this example, a 34 DC would have a 0.4 db through loss at channel 2 frequencies. The next span of cable would have appropriate losses to be calculated to determine the next value of DC to use.

There are also two-port directional couplers, sometimes called directional taps. This would combine a splitter on the output or tap port of a single port unit, in one enclosure. For your purposes, five two-port DCs appropriately designed would service ten units in a spine-like arrangement.

In the drawing below, the values have been exaggerated by reducing them in an un-calculated manner. You would need to know the frequency range you plan to use as well as the losses for that range in the coaxial cable to be used.

The last connection would be a splitter, which will create a 3.5 db loss for each leg. That is to say, if you have 15 db signal level, you'll get 11.5 db on each side of the splitter. It may not seem like much, but there is a 3 db loss for the split and a 0.5 db loss for the device. In RF terms, 3 db is half-signal. If the entire system were splitters, you'd have 1/32 of the signal after five splits!

Even a digital system uses an analog RF signal to carry the signal, which is equally susceptible to attenuation through the cable and devices.

Equalization of the signal may not be a problem, but if it's strictly analog, you'd want to ensure that it's within limits. Equalization refers to higher frequencies dropping off faster than low. It's not as simple as cranking up the higher channel levels, as too much signal level is just as bad as too low.

Digital configurations are more forgiving and an entirely different realm of design.

crude cable television design

  • Wow, very good information. That is good to know about directional couplers instead of splitters, I didn't realize those existed. – lucky.expert Aug 22 '17 at 18:08
  • I once was a cable tv guy and part of the early segment of my career was designing small layouts. I later wrote a Basic program to run on a Sinclair ZX-81 computer to do all the number crunching. Nine dollars and ninety-five cents a month for 12 channels. Kinda dates me, doesn't it? – fred_dot_u Aug 22 '17 at 19:04
  • After doing some more thinking, I think I can run 4 separate feeds from the office since they aren't all in the same direction, and use directional couplers to get 2/3 drops on each run as you drew up. Thanks for the knowledge! – lucky.expert Aug 23 '17 at 1:59

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