Re: Does complex conjugate invert IQ ?

[Daniel Estévez]

Indeed. Also, in case that's a long read (I think it's interesting 
anyhow), the bottom line is that IQ swap and complex conjugate are 
basically "the same" operation for most purposes.

This is because if the swap is S(a+bi) = b+ai and the conjugate is 
C(a+bi) = a-bi, then S(z) = iC(z), so we see that the only difference 
between both operations is a 90º phase rotation.

Both of these operations accomplish flipping the frequency axis, which 
is probably the main reason one would use them.

Best,

Daniel.

El 13/12/21 a las 17:14, Albin Stigö escribió:
> This might be of interest.
>
> https://www.dsprelated.com/showarticle/51.php 
> <https://www.dsprelated.com/showarticle/51.php>
>
>
> --Albin
>
> On Mon, Dec 13, 2021, 16:45 Cyrille Morin <cyrille.morin@insa-lyon.fr 
> <mailto:cyrille.morin@insa-lyon.fr>> wrote:
>
>     Hi,
>
>     You could use a "Complex to Float" to separate the I and Q
>     components, followed by a "Float to Complex", inverting the re and
>     im inputs.
>
>
>     Le 13/12/2021 à 16:31, Rachida SAROUI a écrit :
> >     Thank you for responding, but what I meant by invert is swapping
> >     the I and Q components of the signal.
> >
> >     Le lun. 13 déc. 2021 à 16:25, Fabian Schwartau <fabian@opencode.eu
> >     <mailto:fabian@opencode.eu>> a écrit :
> >
> >         Complex conjugate only inverts the imaginary (Q) part of the
> >         signal.
> >         If you want to invert both, just multiply with -1.
> >
> >         Am 13.12.21 um 16:22 schrieb Rachida SAROUI:
> >         > Hi everyone,
> >         >
> >         > I need to invert the I and Q of a complex signal. Does the
> >         block complex
> >         > conjugate do the job?
> >         >
> >         > Thank you
> >         >

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