Re: [Discuss-gnuradio] FIR filters and set_history()

[George Nychis]

Dan Halperin wrote:

> In the normal code in the trunk, this works just as expected. But when
> you make your custom vectors, you only pull noutput_items out of the
> input buffer, not noutput_items+history.


You're exactly right with this, I'm forgetting that I'm creating new 
input buffers but only extracting noutput_items from the original input 
buffer.  I tested this and get the exact output I'm looking for now.

One line diff:
-  split_complex(in, noutput_items, in_real, in_imag);
+  split_complex(in, noutput_items+history(), in_real, in_imag);

I needed to pull history() additional items from the input queue, which 
makes sense.

> Also, my understanding of a normal matched filter is that it does the
> normal complex multiplication (by the conjugate, but I'm assuming you've
> done that already before building the taps), not the real-wise and
> complex-wise ... inner product, I guess? ... as you've defined it.

I had thought I could use gr_fir_filter_ccc, setting my taps to be the 
time reversed version of the input signal, but found that it wasn't 
correlating.  I think what I was missing is the fact you are suggesting 
that the taps be the complex conjugate of the input signal?

- George