How cable works: Inside a Time Warner head-end center

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If you, like many people, turn off your brain when you turn on the TV, you probably don’t think too much about how it all works. But like many other things technological, it’s pretty darn complicated. For instance, if you’re a cable watcher, the code that transmitted that image of Olympic sprinter Usain Bolt traveled 50,000 miles in seconds (even faster than he runs) to get to your television.

We’ve aired lots of complaints about Time Warner Cable’s customer service woes and its lack of high-definition offerings. But last week, Time Warner invited me into its head-end facility to show me just how complex it is to get cable and high-def channels and on-demand movies and voice-over Internet protocol to your home. If you’ve ever wondered how cable works, what exactly giant satellite dishes do or what happens to satellites in space once they run out of gas, continue reading below the jump.

TV starts, of course, with a program such as the Olympics or ‘The Daily Show with Jon Stewart.’ Signals transmitting that program are beamed to satellites 22,500 miles up in space and then ...

... sent 22,500 miles back to giant satellite dishes that receive them. The signal bounces off the surface of the dishes (which are so big you could lay across them from head to toe twice) and jumps to something called the focal point, which is that branch coming out of the dish, kind of like the stigma of a flower.

Time Warner calls the centers that receive these signals ‘master head-ends.’ One of Time Warner’s two master head-end centers for the Los Angeles region is located in a Culver City lot, below a hill covered with dying grass. Eight giant satellite dishes sit in the parking lot, and each dish is responsible for receiving programming from certain channels. Places with lots of dishes are called ‘dish farms.’

Up in space, the satellites’ motors are calculated to keep them in sync with the earth’s rotation. The satellites travel at the same speed that the earth is spinning, so that Time Warner’s giant dishes always point at the same satellites.

(Once the satellites run out of gas, they’re propelled away, often toward the sun, where they eventually burn up or join the 15,000 other pieces of space debris drifting around. Twice a year, the satellites are aligned in such a way with the sun that heat overpowers the technology, and some of your cable channels may be disrupted for a few minutes.)

From these satellite dishes, cables the size of fingers take the signal into the head-end center, a nondescript squat building that looks like it either has something to do with cable or else is the front for the Bureau of Paranormal Research and Defense. Inside, servers hum and air conditioning whirs under the floors to keep everything cool. Servers and cables are everywhere, as are a few TV screens showing cable programs so that the engineers, who are there 24/7, can be sure everything is working right. Or maybe the screens are just there to keep the engineers amused in the windowless room.

Here’s where it starts to get complicated. In the main room, thick cables shoot up from the floor and plug into a rack. Each cable represents a channel, and if you were to unplug one such cable, that channel would go down throughout Los Angeles.

From the rack, the data is sent to an encoding device, which allows Time Warner to play it anywhere on its digital lineup and format it into different packages. Next, yellow, green and gray wires go to something called a combining network, which unites cables representing video, high-speed Internet, telephone and video on demand into one cable. That cable goes into a fiber optics transmitter, which moves the data into colored cables the size of really thin strands of hair.

Fiber optic cables go either under or above ground to a different area in the city, to facilities called nodes. In the nodes, information in the hair-sized fiber optic cable is transmitted back onto finger-sized RF cables, which then go to your home. If you don’t have as many high-def channels as you’d like yet, it’s probably because Time Warner is updating the node near you.

Head hurt yet? We haven’t even begun to talk about digital ad insertion, which is where Time Warner places local ads in national programs, or pricey equipment called CMTS that transmits high speed Internet and VOIP calls. That takes even more whizzing, complicated equipment, which can determine where gamers live based on the areas that need more bandwidth.

If you made it this far into the post, you’re doubtless impressed by the technology, and maybe even a little nervous (or else you’re my grandmother -- Hi, Fritzi!). So many wires. Couldn’t a malicious someone with a big pair of pliers take down our whole entertainment system pretty easily, depriving us of very important knowledge such as who is going to win the medal for trampoline? Evildoers aside, couldn’t a big klutz wreak havoc on our cable-dependent lives?

Rest assured: Time Warner has two master head-ends to back up each other, and 18 other facilities where the data can be processed, repackaged and sent to homes.

-- Alana Semuels