Can You Run OTA Antenna TV and Internet Feeds on the Same Coax Cable? Yes!

So far we’ve cut the cable TV cord and maximized our over-the-air (OTA) antenna reception for our TVs; however, if you're like me, there's a snag with sharing the antenna's signal with a TV that also depended on one coax (that's a coaxial cable if you're new to these procedures) to provide cable TV and the Internet feed.  Fear not, for I would not lead you astray and will show you the way.  This is the third chapter in this OTA adventure, so in case you missed what has been covered so far, here's a recap:

Chapter 1 - Receive HD channels on your TV with an over-the-air (OTA) antenna

Chapter 2 - Optimize the antenna signal for all TVs with splitters

Chapter 3 - Run an antenna's signal on the same cord as your Internet feed

Chapter 4 - Stream videos from cable stations with a media server

When my cable TV was installed, a coax was run from the cable box on the bottom floor to the upstairs TV, which is where my main antenna is now located.  When I went about maximizing my reception, I wanted to use the coax installed by the cable company to feed the signal from the main antenna upstairs back down to the single coax connected to the downstairs TV.  The problem was that the coax from the cable box to the downstairs TV was still being used to connect me to the Internet (you only need one coax to run cable TV and the Internet).  Because cable TV and the Internet feed use the same signal, a simple splitter is all that's needed to give the TV its channels and your Internet router its Internet data.

The fix in my head was to combine the main antenna's signal with the Internet feed on one coax...if that was even possible.  I did lots of research on audio/video forums to see if this was possible and almost everyone said it was impossible.  Most said that you could not run the two different signals on the same coax because they run at different frequencies, there’s an issue with interference, and the gods would not allow it during the summer solstice.

However, I found one person who said you could use a device called a diplexer.  It sounds ominous, but really it’s friendly once you get to know it. It took plenty of research to confirm that a diplexer would do the trick so let's hope you found this blog in less time than it took me to learn about diplexers and type this entry.  Here’s how I used to diplexers to help cut the cord and solve this problem; your setup may differ, but the concepts still apply.
Step 1 - Return to your sketch in chapter 2 of the optimal setup for your OTA signal, now knowing that you can run the OTA signal on the same coax as your Internet feed. Recall that using one antenna’s signal on multiple TVs does not decrease the video quality even when they’re all on and showing different stations.

 In my case, the "satellite antenna" is the Internet service provider's feed to the house, the red line is the single coax that carries both streams, and the "satellite signal" is the Internet feed that finds its was to the router. 

Step 2 - One diplexer is needed to combine the antenna signal and Internet feed and another diplexer is necessary to (re)split them. Diplexers look like splitters and have all female ends just as splitters do. Go online or your electronics store and purchase your diplexers and connectors as necessary, holding onto that receipt just in case this whole experience fails. 
 
Step 3 - With your diplexers in hand, setup your main antenna and run its signal down to where you want to combine it with the Internet feed. It's okay to use a splitter anywhere in the feed’s path, no matter how far from the combination point, to reach other TVs before the fancy combining happens.

Step 4 - Go where you want the antenna’s signal to combine with the Internet feed.  Based on my story, this was outside on the first floor because of where the Internet (and cable TV) box was located.

Step 5 - At the combination point, you should have a free hanging coax with a male end that finds its way back to the main antenna.

Step 6 - Take one of the diplexers, we’ll call it diplexer A, and locate the side with two connectors (the bottom side in the picture above).

Step 7 - Screw the male end of the coax from step 5 into one of the bottom side diplexer connectors, the side with more than one connector on it.

Step 8 - Unplug your router (and modem if you have one).

Step 9 - Locate the box that pulls the Internet feed into your house, this is probably the same as what was/will be your cable TV box.

Step 10 - Connected to the Internet box is a coax that runs into your house and is split with a familiar looking splitter.  Disconnect this coax from the splitter, or closest connection point to the box, leaving the other end of the coax connected to the Internet box.

Step 11 - Take the free hanging Internet feed's coax (and its male end) and screw it into the other “IN” female connector of diplexer A.

Step 12 - At the combination point, you now have diplexer A being fed the signal from the main antenna and your Internet feed.

Here's my setup proving something, I'm just not sure yet.

Step 13 - Locate the coax that runs into your dwelling; one end should still be screwed to the splitter that was connected to the Internet feed's coax.

Step 14 - Unscrew this coax from the splitter.  Congrats, you’ve got a free splitter from the cable company!

Step 15 - Take this same coax and screw it to the “OUT” female connector of diplexer A.

Step 16 - If all is well, diplexer A still has the antenna coax and Internet feed coax connected as inputs, and now has the coax that goes into your house connected to its output.

Step 17 - Take hold of the other diplexer, let’s call it, oh I don’t know, diplexer B.

Step 18 - Follow along the coax that goes into your house and locate its other end where you want to (re)split this super-mega-awesome combined feed.  In my case, the cable company setup a coax that ended with a splitter sending the signal to the TV and Internet router.

Step 19 - Connect this main coax to the “OUT” female connector of diplexer B (it's the lonely port in the picture above, you can't miss it.  Well I guess you could miss it, but then this whole thing won't work well).

Step 20 - From the indoor splitter near you, unscrew the coax connected to your home's Internet router and then unscrew the coax that connects to your TV.  Again, you're removing them from the splitter and not the router or TV.  The router and TV will keep their coaxes attached.

Step 21 - Locate the coax that runs to your home’s Internet router and screw its free end to a connector on diplexer B with multiple connectors (bottom of the picture above).  In the pictured diplexer, the bottom connectors now become "OUT" connectors and the connector that's alone on one side becomes an "IN" port.

Step 22 - Locate the TV’s free coax and screw it to diplexer B’s other “IN” or “INPUT” port.  If you want to run multiple TVs from this feed, connect a splitter to this port on diplexer B and connect TVs from there as usual.

Step 23 - Turn on a TV connected to the diplexer and see if you receive signals as done in Chapter 1, step 19.

Step 24 - Any luck? If so, high five yourself, I may have been speaking the truth afterall.

Step 25 - Turn on all TVs receiving the main antenna’s feed and see if they receive channels too, setting them up as necessary.  Pretty cool how you can watch different channels on each TV at the same time, right?

Step 26 - Plug in/turn on your Internet router and let it reconnect to the Internet; then plug in/turn on your modem and let it reconnect to the router.  These devices should reconnect to the Internet on their own.  If you see lots of lights flashing in good ways then we’re doing alright.

Step 27 - Find yourself a device that connects to the Internet and see if it can connect. Any luck? If so, give yourself two high fives! You may now have every TV tuned to different channels while streaming Internet video without any issues on any of them.  As with any antenna signal splitting, channel reception is tied to the quality of a single antenna, but it should have been placed in a location that nullifies this issue.

Step 28 - Congratulations! You are now running the OTA antenna signal on the same coax as your Internet feed, have maximized the signal for every connected TV, and can wow people at your next cocktail party by saying things like, “I spent the weekend working with coaxes, splitters, and diplexers and I’m awesome.”

In the fourth and final chapter, I’ll talk about replacing some of those cable channels you used to watch by relying on a media player and streaming video.