Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: John Higdon Newsgroups: comp.dcom.telecom Subject: Re: Data Access Lines Message-ID: <8293@accuvax.nwu.edu> Date: 25 May 90 04:40:57 GMT Sender: news@accuvax.nwu.edu Reply-To: John Higdon Organization: Green Hills and Cows Lines: 20 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 387, Message 3 of 12 Chip Rosenthal writes: > dBm is commonly used to specify a level referenced to a "digital ^^^^^^^ > milliwatt" signal. This is a 1004Hz sine wave of 1mW power into > 600ohms. What was it before digital technology? I've always heard it referred to as simply the "milliwatt". Also, to be technically pure, dBm can be a reference to one milliwatt into any impedance, as long as it's a milliwatt. The 600 ohms comes into play because everyone knows that that when you measure 0.775 volts on across 600 ohms, you have a milliwatt. If you measure 0.949 volts across 900 ohms, you still have a milliwatt. And it is still 0 dBm. John Higdon | P. O. Box 7648 | +1 408 723 1395 john@bovine.ati.com | San Jose, CA 95150 | M o o !