As a result, when your router receives a packet, it knows which device the packet is supposed to go to. This IP address then gets attached to any incoming or outgoing packet. When a device is connected to your router, the router assigns it a unique identifier, called an IP address. But what if you have a smartphone, a game console, and a network printer all connected at once? The modem has no way to know which packets are supposed to go to which device. This data is transmitted in chunks called “packets.” If there’s only one device connected to your modem, that’s no problem. What in the world does a router do? The answer is that a modem is simply delivering data. So, a modem connects your house to the internet. So if you have digital cable but not home internet, there’s still a small modem in your home! If you have digital cable, your set top box uses its own internet connection for the menu and other features. The most common example of this is the humble TV set top box. That said, you’ll actually find small modems inside of some other devices. Some modems also have a second coaxial output port for connecting to a TV or other device. Typically, there’s a single coaxial input on the back, along with an Ethernet output. These days, most modems are compact devices, about the size of a paperback book. A CMTS is basically a fancy modem, which is designed to connect to many users simultaneously.Ĭable modems vary in design and quality, but they all have some of the same basic components. On the service provider’s end, this is done with an industrial cable modem termination system (CMTS). On your end, this is done with a cable modem. Much like with an old-school modem, this data needs to be converted between a TV signal and digital data. The incoming signal from your internet provider is called “downstream” data, while the outgoing signal is “upstream” data. This is why residential internet speeds are typically slowest at the busiest time of day. But if many people are online, they’ll eventually need to start sharing channels. There will be more than one outgoing and one incoming channel available. If there are only a few people online, you’ll still get the maximum. If it’s three in the morning and there’s nobody else online, you’ll get the maximum speed. The reason for this is that entire neighborhoods can be served by a single coaxial line. Keep in mind that your internet provider’s maximum speeds are called “maximum” for a reason. Outgoing data only requires a 2MHz band, since you don’t often need to upload as much as you download. This way, you can get Gigabit internet in your home, with no more strain on your cable than a TV channel. As a matter of fact, incoming internet data can be transmitted over a 6MHz band, just like a TV channel. Even so, it actually doesn’t take that wide of a frequency range to provide a strong internet signal. A coaxial cable, meanwhile, has hundreds of MHz of signal to play with. How in the world do you get hundreds of channels across a single cable? How do you still have room for an internet signal? The answer is that a single cable channel only occupies a frequency range of 6MHz. And that’s why almost every modern modem is a cable modem.Īt this point, cable TV subscribers will have an obvious question. For such a short run, there’s really no need for anything faster. Even newer, fiber-optic internet services use a cable connection from the curb to the house. To get faster speeds, you need a bigger wire, which is why providers started switching to cable internet. But even they aren’t as fast as modern high-speed internet. We should point out that there are faster versions of “phone” technology like T1 and ADSL lines. If you’re old enough to remember 90s internet, you remember taking half an hour for a song to download. At the time, it was mind-blowing technology! However, phone lines have a fairly limited capacity. This allowed you to send data signals over the phone line. “Demodulation,” on the other hand, means converting audio signals back to digital again. “Modem” wasn’t originally a word it was an abbreviation for “modulator-demodulator.” “Modulation” in this case means converting digital signals to audio. When we say “modem” today, we’re almost always talking about a cable modem. From there, we’ll be able to work through everything else with relative ease. Well, that and an active internet connection! But what’s the difference between the two? And can you ever get away with using just one or the other? We’re going to talk about how the technology works, starting with the internet signal itself. If you’re setting up a home internet connection, there are two main components required: a router and a modem.
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