Amati vs Westell, DMT vs CAP ADSL Message Board

To: Vance Schoonover who wrote (1288)	1/7/1997 10:26:00 AM
From: Luke Smithwick	of 1365

Vance, I joined GTI last month. I previously worked at Bell Laboratories in the DSL business. Unfortunately, as such, I have not seen a true unbiased discussion of CAP vs. DMT. I do, however, know colleagues in the industry who are in the process of writing papers dealing with the same. BTW, these are people who work/worked for the RBOCs and ISPs and have tested CAP and DMT in the REAL WORLD. As far as CAP vs. DMT - both were invented at Bell Laboratories. Bell Laboratories continues to be somewhat line code agnostic as they sell both technologies - but for different environments. They learned long ago that there are slight differences in performance depending upon impairments. The DSL environment is better suited for single carrier systems (CAP/QAM). Other environments are better suited for DMT. Why do some of the DMT vendors refuse to acknowledge this??? Note I said some... At any rate, since there are no properly performing DMT chips available at the present time, a true and fair comparison cannot be made. Note that CAP chips, that perform rather well have been available for some time and are selling in modest quantities. I believe that you will see the actual differences when both systems hit the streets (provided the ADSL market takes off). I would be really careful with my investments in Si vendor stocks until then... Take care, Luke PS try globespan.net