Ah, the many different terms you’ll learn once you start diving into commercial RF distribution. Some, like “mini-mod” will sound positively comical.
A mini-mod is a small modulator. But let’s unpack that a bit.
What is a modulator?
If you’re using a commercial “headend” system, you’re taking a bunch of TV channels and through some miracles, making them all live happily on the same wire. Then, when they get to the TV, the person watching can choose which channel they want.
The most important of those miracles is called “modulation.” A normal TV signal takes up all the space on a single wire. This is called “baseband” video. A modulator takes that signal and reconfigures it so it only takes up a small amount of the space on the wire. It shoves all of it into a small range of frequencies 6MHz wide. This is called modulation and the device that does it is called a modulator.
The trick is, you put each channel you want into a different range of frequencies, so they don’t interfere with any other frequencies. Then you can combine them fairly easily on the same wire.
What’s the trick about that?
In the older days of TV reception, there wasn’t much of a trick to it actually. Truth be told, even with the new digital signals it’s not super hard. But when you’re going digital, a modulator has to perform two other tasks that have been pretty hard to do: encoding and compression.
Encoding
A digital signal is a bunch of ones and zeros. The real world is, well, the real world. (Unless it isn’t.) In order to translate a picture into a digital signal, it must be encoded. Encoding means setting up the rules that determine how the digital signal and the real world are going to interact. Here are some of those rules used by television encoders:
- There are 1,920 dots from left to right.
- There are 1,080 dots from top to bottom.
- The first dot is red, the second is blue, the third is green.
As you can see these are a set of simple rules that make it possible for the TV, the camera, and everything in between to agree how real life is turned into pictures. Digital encoding takes a certain amount of processing power and ten years ago, that meant a big chunky box.
Compression
If all you did was have big long streams of ones and zeroes, it would take about 6 TV channels to show just one video stream. That obviously wasn’t going to work for anyone, since the whole idea was to have TV channels that were the same size as the old analog ones, and in a market like New York where there are 100 TV program sources, they wouldn’t fit.
Compression is the process of crunching down all those numbers in order to make the whole thing fit in the space that’s required. There are a lot of complex ways to make this work, and you can also choose how small you want the final result to be. Make it too small and the picture quality suffers. Make it too big and it won’t fit in the channel you want it to fit into.
After the fancy math is done, a TV signal takes anywhere from 1/4th to 1/20th of the space it used to and if it’s done right, you’ll barely notice the difference. However, by early 2000s standards that math was pretty hard to do and it took a big machine.
Enter the full-size modulator
If you were putting together a digital TV headend in 2006, you could count on a set of boxes about the size of 4 VCRs stacked on top of each other, for each channel. By 2010 that had “shrunk” to about two VCRs stacked on top of each other. But put together a 100-channel headend and you’re talking about a lot of space.
Full-size modulators were great, but they took a ton of space.
And now, the mini-mod
Finally, a few years ago, we started seeing mini-mods like the one in the picture at top. They are designed to fit side-by-side in the space where one full-size modulator sat. With a mini-mod you can fit 8 modulators in the space you used to need for one. Now you’re finally talking.
Mini-mods are used in the COM2000 system from DIRECTV to put up to 32 channels and 32 DIRECTV receivers in the space where one modulator used to sit. That’s a massive space savings.
Mini-mods are also usually more efficient on power and generate less heat, requiring less air conditioning. They work so well because computer processors are a lot faster and more efficient than they used to be. Just like your full-sized PC gave way to your cell phone, the mini-mod has overtaken full-sized modulators.
Getting a mini-mod
There’s really only one place to look for any sort of modulator. If you’re setting up a high-end home, bar, restaurant, hotel or any sort of commercial space, you need to call the folks at Solid Signal. The number is 888-233-7563 and they’ll be able to put together a custom quote that works for you. Chances are you’ll get mini-mods that help you save power and space, too.
