Finally, a cable company you don't hate!
Finally, a cable company you don't hate!
Sometime in 2020, I was watching Star Trek with my wife, my mind drifted, and I started wondering about how cable TV worked. For some reason I had a lot of extra time on my hands around then, so I started learning about what all was involved and then, arrogantly, declared to anyone willing to listen, that I was going to create my own cable system.
The more I thought about the project the more I fell in love with it. It wasn’t just a project, it was (and is) a never-ending collection of projects. It’s a theme around which projects can sprout. I am a software engineer by trade, and one of the aspects of the career I treasure most is the neverending stream of opportunities to learn new things. This is my model train set. It’s never complete, and there will always be something more I can do or change with it. When I need a break from working on it, I can watch it. When I want to and am able to, I can find a new part of it to obsess over.
Even if this doesn’t inspire you to build your own cable system, I hope you can appreciate the novelty of it, and I hope you have or find a hobby that brings you the amount of joy this has brought me.
You can think of a cable system as multiple videos playing at the same time, and your TV knows how to focus on just one at a time. Imagine a 50 channel cable service (small by today’s standards), then imagine a stack of 50 DVD players all playing something different. You can take the video and audio from each DVD player and put it on a separate radio frequency. This is called modulation. You can then take those 50 separate signals, all on different frequencies, and combine them to flow on a single cable. At that point, your TV just has to choose one frequency out of the 50 to focus on at a time. That’s called tuning. Each channel has it’s own frequency, so if you modulate to a channel’s assigned frequency, you’ll see and hear it on that channel.
Now, it would be a huge pain to swap discs constantly as you change what show is on, but people used to do this! Well, they most likely used tapes or maybe laserdiscs in some cases. Still, we’re talking about running multiple channels ourselves! We can’t be swapping tapes or discs constantly. Instead, what I’ve done is used a series of small, low cost, low powered computers to play the videos based off a centalized schedule. Oh, and I have them inserting commercials as well for a more authentic experience.
I have a small server rack that contains several Raspberry Pis (one per channel). They know what to play by asking the central scheduling server, which is also running on a Raspberry Pi. That one also doubles as the guide channel.
The videos are stored on a Synology NAS, and all the channel Raspberry Pis have read-only access to the shared directory. Each Raspberry Pi runs a piece of software I call “Technical Director”, which is what consults the scheduling server and queues up shows and commercials. It displays the video content in fullscreen using libVLC.
The composite output of the Raspberry Pis each go into a separate modulator. I use Blonder Tongue mini-modulators, model MICM-(b, c, or d). 12 of these slot into a 2U rack which also contains a power supply for them. The Raspberry Pis are powered via PoE fed by a switch on the rack. The modulators all connect to inputs on a Blonder Tongue OC-12 signal combiner. This results in two outputs, one that has been attenuated enough for direct use, and another that has not been attenuated at all and has a very strong signal coming off it. This stronger output was made to be split many times and still have a decent strength. This equipment was likely pulled from a school or motel. I got it off eBay.