The (R)evolution of the Modem

Oct 30, 2012 cable, cable modem, dialup modem, 0 Comments
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The word “modem“ stands for modulate-demodulate. That’s fancy tech-talk for letting your computer talk with your Internet Service Provider and, through said computer modem, the world of the Internet. These handy little devices have come a long way since the early days. From devices that were so slow that even transferring a small text file could take half a day, to today’s high-speed broadband modems, they’ve experienced more of a revolution than an evolution since their invention a few decades ago.

The Early Days Before the Internet

AJ 311 Acoustic modem

Photo Credit: Wikimedia Images by Mikael Restoux

Before there was the Internet, there were bulletin board services. We referred to them as BBSes for short and we had to call them. In the very early days, these devices were the size of a small suitcase. You had to dial the phone number you were calling manually, wait to hear the tones, and then connect the handset to the acoustic coupler. This was a part of the device that looked like a mold for the telephone’s handset.

If you’re old enough to remember the old dial-up computer modems, or have used a fax machine, you know what tones I’m talking about. Back then, computers (and the programs they ran) talked to each other using these tones. The only digital part of the communication was before and after the computer modem did its job.The device in your computer would take the ones and zeros that your computer and programs generated and modulate it. In other words, it would turn it into the tones the phone system required. When the data embedded within those tones reached the computer you were “talking” to, they would be demodulated, or turned back into ones and zeros that the computer and programs could understand.

US Robotics 56K Modem Front

US Robotics 56K Modem - Photo Credit: Wikimedia Images by Xiaowei

The first computer modem that I saw was a 300 baud Rockwell device, that, like I said, was the size of a small suitcase. The first one I owned, a few years later, was a 2,700 baud unit and was the size of a midsize clock radio and it connected to my computer using phone cords. No more acoustic coupler. This was back in the mid-80s. Within a year or so, that was replaced with a smaller unit that was installed in my computer and operated at 9,600 baud. A small (4″x8″) picture would take at least an hour to download. My first one was fast enough to allow almost real-time text conversations. The last one I owned was 10 times as fast, at 96 Kbaud. Well, actually, it was a 56K device that used compression to get a perceived 92 K bitrate, or speed.

Enter DSL Modem– No More Tones & Much More Speed

US robotics isa modem

US robotics isa modem – Photo Credit: Wikimedia Images by Tremaster

Right around 1997, phone companies started rolling out a new service for higher speed Internet connections called DSL, or Digital Subscriber Line. The communications were completely digital, and of much higher speed. But they still required a modem, which was connected to a standard phone outlet. And, even better, if you wanted to be able to use the phone AND the Internet at the same time, you could, without requiring a second phone line/number! All you needed was a DSL filter to filter out the digital communications on the line and you were set.

DSL gave speeds of up to about 1.5 Megabits per second.You could even use a router or hub (with Network Address Translation activated) and you could share the Internet connection with multiple computers in the house. One problem that people noticed with DSL was that if they were more than a couple of kilometers from the phone company’s switching office, their speeds dropped off dramatically. Even though DSL was about 300 times faster than the fastest dial-up connection, it still wasn’t fast enough for most people.

We wanted more speed.

True Broadband Cable Internet

T-DSL Modem

T-DSL Modem – Photo Credit: Wikimedia Images by Heidas

The Cable TV companies decided they wanted to get in on the action of providing Internet services to customers, so they came up with a way to send the digital network information over their RG-8 coaxial cable, and from the cable to your computer. What they used (and still use) is a called a cable modem.

This device connects to the same cable network that you use to get your TV programming and it strips the Internet information (data) from the cable and sends it to your computer, usually through a router (especially if you’re smart). Not only does the router allow you to connect up to 255 computers to a single Internet connection, but it also helps block unwanted attempts at entry to your network by “bad guys.”

Thomson Modem

Thomson Modem – Photo Credit: Wikimedia Images by Maduixa

Cable Internet overcame most of the problems that DSL had, especially the distance from the central office problem. And it delivers connection speeds of as high as 20 Megabits in some areas. However, it does have one drawback in that you’ll almost never experience the maximum advertised speed because the connection is shared with everyone in your neighborhood. This is because the cable to your house is actually tapped off of a main cable coming from the company’s main office in your area.

Fax machines still rely on these devices to do their jobs. You can hear them every time you send or receive a fax. In fact, until fiber to the home becomes ubiquitous, we’ll always have needs for these venerable devices.


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Mike is a certified low voltage installer with over 10 years of professional experience in the field, much of it working for Cable TV companies. He also has over a decade of experience in the computer field as a network engineer and support specialist. Mike's hobbies include installing high-end audio and video systems.

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