Re: Complex to 2x real - how?

John E. Hadstate wrote:

> 
> "dotter" <dotter@[EMAIL PROTECTED]
> wrote in message 
> news:gcltn3$hjb$1$8302bc10@[EMAIL PROTECTED]
> 
>> Hi,
>> I'm struggling with how to convert a complex data stream into a real 
>> stream with the same bandwidth and twice the sample rate.
>>
>> How could this be accomplished?
>> Thanks!
>>
> 
>
http://groups.google.com/group/comp.dsp/browse_frm/thread/4246297bae7f3fa3/359dce97646f8740

> 
> 
> Look at #8 in the thread from Rick Lyons.
> 

Thanks for the replies, I appreciate I could have been a bit more 
forthcoming regarding my homework problem (not!).

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.

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.

I've looked at some of the suggestions eg the sequence
Real = I(n), Q(n) -I(n+1), -Q(n+1)
which certainly provides some aspects of what I expect but the image 
below 0Hz has unexpectedly small amplitude.

Suggestions welcome.