What Is a Cable Modem?

The info you need on this home internet workhorse

A cable modem is a crucial piece of hardware you'll either receive from your internet service provider or purchase separately. It receives and sends information like emails, web pages, text messages, and other data through the primary data connection.

An Ethernet cable plugging into a modem

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What Does a Cable Modem Do?

Like all modems, the cable version handles and distributes internet information for a home or building. What makes the cable version unique is it moves data through the same jack and cables you use to watch TV.

Most companies that offer cable internet used their existing infrastructure to add the extra function on top of TV programming. This transition is similar to wired phone service providers who expanded into their high-speed internet, DSL. You'll usually be able to save money by bundling cable service with internet through the same provider.

Cable internet is a broadband type, which means it can carry out multiple processes simultaneously. It's generally faster than DSL but slower than newer fiber technology.

What Is the Difference Between a Modem and a Cable Modem?

Every modem does the same job: it serves as a bridge to receive and send data over the internet. The differences between different kinds ultimately come down to the connection they use to do their job.

The oldest modems used a house's phone line to receive the internet, but they couldn't run simultaneously. If you were on the computer and received a call, you would lose your connection. Faster DSL internet also uses the phone line, but it works on a different frequency so you can receive calls while sending emails and not have to worry about interference.

Cable internet bypasses the phone entirely and uses a building's cable TV jack and coaxial cables to run the internet. In contrast, fiber modems use a specific wall port the ISP has to come over and install (it'll mean another hole in your building or at least your floor).

Will a Cable Modem Work for Wi-Fi?

The hardware that gives you a wireless internet connection is compatible with most, if not all, types of connections. Your internet service provider will probably issue you a cable modem with a built-in wireless router. These devices can handle the data streams in and out of a building and transmit them through the air.

If your ISP doesn't give you a combination modem and router, however, you can also buy one separately. You don't necessarily need a router if you plan on connecting all of your devices directly to the modem via Ethernet cables. However, if you intend to use things for which this is impractical or impossible, like smartphones, tablets, or smart-home accessories, you will need to set up a wireless network.

  • How do I set up my cable modem?

    Connect your modem to a TV wall jack with the coaxial cable that came with your modem, then plug in the power source. If you have an external router, connect it to your modem to set up a wireless network, or connect your devices directly to the modem via Ethernet.

  • How do I connect a router to my modem?

    Plug one end of an Ethernet cable into your modem and the other end into the router's WAN port. Locate your router's network name and network key (usually found on the bottom of the device), then connect to the Wi-Fi network on your computer.

  • Why isn't my modem working?

    Potential reasons your modem isn't working include loose or damaged cable connections, miscommunication with the router, overheating, and outdated firmware or equipment. If you can't connect to your Wi-Fi network, then you need to troubleshoot your router.

  • How do I connect my TV and modem to one cable outlet?

    To connect a modem and TV to the same coaxial cable, you’ll need a cable splitter. Connect the cable splitter to the wall socket, then connect the modem and TV to the splitter.

  • What is a good signal-to-noise ratio for a cable modem?

    The minimum signal-to-noise ratio (SNR) requirement for a cable modem is 23.5 dB, but 30 dB or higher is recommended.

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