The terms IQ are increasingly commonplace in amateur radio literature.  Open any copy of Radcom or read anything about Software Defined Radio (SDR) and you will see the terms IQ.  But what are they?

Since transitioning from a cherished black-box radio last Autumn to SDR I’ve been meaning to understand the mysteries of IQ.  Fundamentally, its really very simple.  But I’ve read several descriptions on the Internet which, quite frankly, are just confusing – too many words all trying to convey something that is much easier done visually.

Tonight, I discovered the video below.  It is an excellent description of, not only, IQ but of modulation and especially BPSK, 4PSK and 16PSK.  I highly recommend taking a few minutes and watching even if you are not interested in SDR and IQ.

Andrew
G0RVM