How DSL Modems Work

The above discussion was based on older modems. The newer modems used today are much faster. These are known as DSL and cable. DSL will be handled here. DSLs work like this:

 

·        How DSLs Work: Standard telephone cable has a pair of copper wires that can carry a lot of information. Because of the way the wire is made, the wires are capable of carrying a great deal of bandwidth. DSL takes advantage of this large bandwidth without distorting the overall signal.  

·        DSL and the Phone Line: When the phone line was created, it had certain limitations regarding the use of frequencies. Our voices can be carried at a range of frequencies from 0 to 3,400 Hertz. Compare this to the range that stereo speakers can produce sound – about 20 Hertz to 20,000 Hertz, the frequencies of our voice are small. The bottom line is that the phone wire is capable of handling frequencies past several million Hertz. Being that there is so much more bandwidth available, DSL takes advantage of it.  

·        Limited Distance: The only problem with DSL is of distance. Your signal will be determined by the distance you are from the main or central office. The limit for DSL is 18,000 feet. If the distance to the central station is greater, the quality of the signal decreases. Most DSLs can transmit up to speeds of 8 mbps.

·        Equipment DSL Uses: The two pieces of equipment normally found with DSL includes the transceiver (also known as the ATU-R), at the senders location, and the DSL Access Multiplexer (DSLAM) at the receiving location.