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To: Doughboy who wrote (3484)	4/28/1999 12:17:00 PM
From: Bernard Levy	Respond to of 12823

Hi Doughboy: DMT - discrete multi-tone. DMT modulation is a multicarrier modulation whereby the transmission spectrum is divided into frequency bins, and a different carrier is used for each bin. The advantage of this approach is that the modulation order (say QAM-16, QAM-64 ...) is adjusted to take into account the signal to noise ratio (SNR) in each bin (some bins can be more affected than others by interferers). The equalization is also extremely easy to accomplish. By opposition QAM/CAP modulation uses a single carrier, but a very long and complex equalizer. DMT is also known in the wireless context as OFDM= orthogonal frequency division multiplexing. The rationale for using different carriers in this context is that different frequencies undergo different levels of fading, leading to different SNRs for different frequency bins. DMT/OFDM modulation has a few drawbacks: higher circuit complexity and power consumption, and higher latency due to the Fourier transform which implements the signal division into different bins. Best regards, Bernard Levy

To: Doughboy who wrote (3484)	4/28/1999 12:31:00 PM
From: MikeM54321	Respond to of 12823

"What CPE is involved with DSL? Let's take a practical example: if I sign up with Concentric for a DSL, will they roll their truck to my office or do they just go to the CO? What equipment has to be installed at my premises?" DougHboy, Since Bernard took care of the DMT question, let me take a stab at the others. In regards to the CPE (Customer Premise Equipment?) I believe it's a "splitter" that has to be installed at your home or office. But this depends upon which flavor of DSL you are requesting or is being deployed. See that's the big debate here. Should ILECs or Data CLECs or DSL Provider deploy something that doesn't offer much bandwidth (DSL light for instance) but is relatively easy to deploy because no truck has to roll to the premise. OR Should they go full bore and try to deploy something more complicated like VDSL where a truck has to roll to the premise and not only install a splitter, but a box thing in the house too. But in doing so, mucho megabits of bandwidth will be available to deliver; phone service, Internet connection, AND many, many TV channels. Hope I got it all right. MikeM(From Florida)