Hi Paul,
Am 13.12.2015 um 22:01 schrieb Paul Nicholson:
I'm puzzled by the I/Q inconsistency. Is there no convention
on the signs in the complex mixer? Perhaps it is
vlfrx-tools and ebnaut which needs to change Q sign?
Don't change yours. I already changed mine :)
http://www.qsl.net/dl4yhf/speclab/wavfiles.htm#I_Q_files
Seriously: There doesn't seem to be a convention (at least I didn't find
a better explanation than the one previously mentioned, see the
datasheet of the AD6620). Yours has trigonometric reasons, the other may
have traditional reasons (cos, sin). Similar as angle values on a
compass and in a mathematician's coordinate system.
One prefers the pointer (or needle) to rotate clockwise when the value
increases, the other one counter-clockwise.
For 'downconverters' (like the AD6620) the negative Q sign may have its
reason. For a dedicated 'upconverter' the NCO's Q output may have a
different sign. But this is just guesswork. Maybe someone has a more
convincing explanation for doing it this way ?
Cheers,
Wolf .
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