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Re: [Discuss-gnuradio] FIR filters and set_history()
From: |
George Nychis |
Subject: |
Re: [Discuss-gnuradio] FIR filters and set_history() |
Date: |
Wed, 06 Feb 2008 12:40:08 -0500 |
User-agent: |
Thunderbird 2.0.0.6 (X11/20071022) |
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