RE: [SI-LIST] : Ignorance in I & Q

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From: Ron Kane (
Date: Mon Feb 26 2001 - 16:50:56 PST

I and Q refer to "In-phase" and "Quadrature-phase" components of a signal.
Think of a vector in the X-Y plane at an angle off the X-axis. The
projection onto the X-axis is the I and the projection onto the Y-axis is Q.

In the RF world when a signal is downconverted using a mixing
(multiplication) process you'll end up with only a sine-part or cosine-part
result. Sometimes complex downconverters are used so that both components
are available for later processing / demodulation.


-----Original Message-----
From: Grossman, Brett []
Sent: Monday, February 26, 2001 4:24 PM
Subject: [SI-LIST] : Ignorance in I & Q

Can any of you RF folks out there lend me a hand and tell me what I & Q are,
and why they are called I & Q?

I know this is a simple question, but none of my old RF books seem to
explain (though a few do use these terms).



Brett Grossman
Intel Test Tooling Operations

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