Re: Complex to 2x real - how?

Jerry Avins <jya@[EMAIL PROTECTED]
> writes:

> Randy Yates wrote:
>> dotter <dotter@[EMAIL PROTECTED]
> writes:
>>> [...]
>>> Given the architecture of the device and various FPGA implmentations,
>>> interpolation seems unlikely and more likely to be some cleverness
>>> though I wonder if this is in the implementation space rather than
>>> signal processing.
>>
>> If you simply take the real component and stuff zeros in every
>> other sample to upsample to 2*Fs, you've got what's advertised,
>> although without the "inversion". That is, you'll have a real signal
>> that has the original content from 0 to Fs / 2 preserved in 0 to Fs / 2
>> of the new signal, and the original content from -Fs / 2 to 0 preserved
>> in Fs / 2 to Fs. Since the new sample rate is 2 * Fs, Fs is the highest
>> frequency at the output rate.
>
> Don't you have to filter after stuffing in order to suppress images?

That was the idea - to *preserve* the image! But I realized a few
minutes after clicking the <send> button [1] that you can't just throw
away
the information in the Q signal (i.e., take the real part) - something's
wrong with my thinking.

--Randy

[1] I hate it when I do that!
-- 
%  Randy Yates                  % "She's sweet on Wagner-I think she'd die
for Beethoven.
%% Fuquay-Varina, NC            %  She love the way Puccini lays down a
tune, and
%%% 919-577-9882                %  Verdi's always creepin' from her room."

%%%% <yates@[EMAIL PROTECTED]
>           % "Rockaria", *A New World Record*, ELO   
http://www.digitalsignallabs.com