[LAD] Smallest, simplest, silliest SDR?

[fons at kokkinizita.net]

On Sun, Feb 28, 2010 at 08:35:37PM -0500, Gene Heskett wrote:

> On Sunday 28 February 2010, Gordon JC Pearce wrote:
>
> So did mine Gordon, heck, while I know what it is, and that its symetrical, I 
> could write an FFT or even a butterfly transform with a gun to my head.  But 
> I have sure made heavy use of gear that can do it over the years.

The discrete form is a set of two FIRs I[i] and Q[i]
with

 Q[i] = 0            for even i	
 Q[i] = 2 / (pi * i) for odd i

for i = -N...N, delayed by N samples to make it causal,
and I[i] is just a delay of N samples.

Q is an finite-lenght approximation of the real thing,
so its FR is not entirely flat. If it matters you can
modify I for the same FR to compensate.

Ciao,

-- 
FA

O tu, che porte, correndo si ?
E guerra e morte !