How can a coaxial cable give you true HD?

If you listen to the cable company, it can’t. But they’ve been known to be wrong.

If you’re a cable customer you’ve probably been told at some point that every TV in your house needs a cable box. The old way of sending cable TV over coax, so it would “just hook up” to your supposedly cable-ready TV, went away forever, thanks to an FCC decision from 2016. If you want basic cable, you have two choices. You’ll need a converter box, which the cable company will be happy to rent you. Or, in some cases, they will let you use your smart TV or streaming box. Many cable companies have apps that let people use their smart TVs as their own cable box. The cable company doesn’t care, especially if they’re the ones providing you with internet service

How cable boxes work

Those cable boxes, should you need them, have a coaxial cable connection out to go to your TV, and the output is strictly standard definition. So that raises the question, how can you get HD reception from an antenna if it uses that same connection? Don’t you need HDMI or something else to get true HD?

The answer boils down to… over-the-air antenna isn’t the same as cable. Over-the-air antenna signals are designed to go through coaxial cable into your TV’s antenna input. There’s no need to use an HDMI cable or anything like that with your antenna. You’ll need an HDMI cable to connect a cable box, streaming box, or something like that… but not for an antenna. There your good-old-fashioned coax comes to the rescue and it does it perfectly.

The little secret that cable companies don’t want you to know

Here’s something they don’t want you to know. You can absolutely run HD programming over a cable, anytime you want. The reason it’s not done has more to do with copy protection and less to do with technology. If you could connect up your TV or DVR with a coax cable, then you’d also be able to make perfect digital copies of your programs like you can with over the air programming. Obviously the broadcasters don’t want you to do that.

Broadcasters use a technology called SDI which carries pure, uncompressed video over a coaxial cable. This ensures the best possible quality at every step. But it’s practically impossible for regular folks to buy and use. There’s an agreement in place that SDI equipment won’t be offered to consumers. Pretty much everyone has signed off on this. They know that if they don’t, they won’t be able to use encrypted content. All about the dollars, folks.

Solid Signal can help

If you do want to produce high quality video the way that broadcasters do, we can help. Solid Signal has the best selection of broadcast-quality video equipment. You’ll find things you won’t find anywhere else. All you have to do is shop at Solid Signal. Not sure what you need? Call us! The number is 888-233-7563. We’re here during East Coast business hours. If it’s after hours, just fill out the form below. We’ll get back to you, usually within one business day.

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 10,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.