Private Lines
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Private Line covers what has occurred, is occurring, and will ocurr in telecommunications. Since communication technology constantly changes, you can expect new content posted regularly.

Consider this site an authoritative resource. Its moderators have successful careers in the telecommunications industry. Utilize the content and send comments. As a site about communicating, conversation is encouraged.

Writers

Thomas Farely

Tom has produced privateline.com since 1995. He is now a freelance technology writer who contributes regularly to the site.

His knowledge of telecommunications has served, most notably, the American Heritage Invention and Technology Magazine and The History Channel.
His interview on Alexander Graham Bell will air on the History Channel the end of 2006.

Ken Schmidt

Ken is a licensed attorney who has worked in the tower industry for seven years. He has managed the development of broadcast towers nationwide and developed and built cell towers.

He has been quoted in newspapers and magazines on issues regarding cell towers and has spoke at industry and non-industry conferences on cell tower related issues.

He is recognized as an expert on cell tower leases and due diligence processes for tower acquisitions.

« Enough nonsense! | | New Nokia Phone »

September 05, 2002

Posted by Tom Farley & Mark van der Hoek at 11:35 PM

Trying to explain D.C. signals

I'm trying to explain D.C. signals for my telephone history series. Take a look below to see if you can understand what I write:

Analog transmission in telephone working. At the top of the illustration we depict direct current as a flat line. D.C. is the steady and continuous current your telephone company provides to carry your conversation. The middle line shows what talking looks like. As in all things analog, it looks like a wave. The third line shows that when you talk the telephone impresses that analog wave on the direct current provided. Thus, your voice varies the telephone's electrical current. Click here for another diagram that complements this illustration. Comments? Corrections?

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