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Message
From: Brian Korsedal<BKorsedal@b...>
Date: Fri Jan 23 17:09:17 CET 2004
Subject: Odp: [oc] FFT for COFDM systems
Thank you,This is sort of the interpretation I have. The O does stand for orthogonal but has nothing to do with the I and Q. It has to do with the fact that all the carriers (something like 1705 in 2K mode) are orthogonal after the iFFT conversion. I guess I will work on a real FFT first because it is much easier than the complex. Then if I have to, I will make a complex. -Brian
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I have understood, that in radio technology it is quite common to send data on
"I" and "Q" portions of the carrier. The carrier can be only real or have also
the imaginary part and imaginary differs pi/2 from real as a vector... as
sin/cos won't correlate with same frequency signal with 90 degrees phase
difference, it is possible to use such carriers to convey totally different
information.
So allthough the names come from complex mathematics, these signals might not
have nothing to do with each other (could be even different tv-channels).
I do not remember how is the case in DVB and such, but "O" in COFDM comes from
"orthogonal", might hint that they are dependent...
Check the standard; if investigating DVB, as it would seem, go to
"attachment.bin
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