Re: Complex to 2x real - how?

On Oct 11, 12:46 pm, System Alchemist <dotter@[EMAIL PROTECTED]
>
wrote:

> I'm looking at the GC1012 wideband downconverter with a view to
> implementing some of the functionality.  The output formatter
> has the option to invert and ****ft the complex output spectrum,
> both these operations I'm comfortable with.

The pictures of the choices in the data sheet should provide a lot of
clarity.

> It also has the option to create a ****fted real output at twice the
> sample rate so that no information is lost, the output spectrum being
> reflected about 0Hz.  I'm pretty sure that this is achieveable without
> interpolation and additional filtering but struggling to understand
> how to accomplish this.

It is either accomplished by interpolation or by keeping a 2x sampling
rate in the first place.

****fting is accomplished by multiplying by a complex "local
oscillator" at 1/4 of the output sample rate (which is fairly trivial
given the actual samples that the LO will generate)

Note that ****fting and "flipping" (spectral inversion) are independent
choices - you can have neither, either, or both.