>
> Hi All,
>
> I have a number of questions related to I/Q balancing.
>
>
>
> Not being a math genius, I am having trouble trying to figure out
how to compensate for I/Q imbalances in software. Are there any good
strategies for balancing the amplitude and phase differences between
the I/Q channels in software?
>
Art,
all is easier if you picture in your mind the I/Q components as the
projections on the X and Y axes of a rotating vector that represents
the analytic signal. Look here :
http://sundry.i2phd.com/iq.gif
So, to balance the amplitude you just multiply one of the two
components by a correction factor. Nothing simpler. A small phase
error means that the angle between the two is no more exactly 90
degrees, but something else, albeit close. Then, applying elementary
geometry, you do a vectorial sum of one of the two components with a
small fraction of the other. The result, if done correctly is again a
couple of vectors at exactly 90 degrees. A quick test with paper and
pencil will convince you.
>
> What would be a good display for checking I/Q balance?
> How would you compute it?
The easiest check is to input, as said in a previous message, a steady
carrier into your mixer. If that results in a single peak on the
correct side of the passband center, then your balance is ok. If you
see two symmetric peaks, usually with different amplitudes, then you
balance has something to be corrected.
>
> And my last question Does anyone have a manual or Doc's for the old
Intel signal processing lab(NSP)? It seems that they have changed to
IPP and I can no longer find any info for the old DLL.
Yes, I have it. You can get it from :
http://sundry.i2phd.com/splman.pdf
73 Alberto I2PHD
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