External library for low pass filtering

Dear Sir,

I understand that gnuradio use FFTW to perform fast fourier transform.
In contrast, what is the library used by gnuradio to perform low-pass
filtering (LPF)?

My intension is to create a custom block to perform digital
downconversion
(DDC).
This is to simulate a SBX daughtercard in receiving RF signal.
I guess this can be done by creating a hierarchical block which include
the
built-in Low Pass Filter, but I am doing this from scratch for learning
purpose.

To summarize my question:
which library is used by gunradio for low pass filtering?
Could it be something like Aquila, SPUC, dspfilterscpp, etc. ?

Thank you very much.

Regards,
Activecat

On Sat, Jan 25, 2014 at 10:46 AM, Activecat [email protected] wrote:

built-in Low Pass Filter, but I am doing this from scratch for learning
purpose.

To summarize my question:
which library is used by gunradio for low pass filtering?
Could it be something like Aquila, SPUC, dspfilterscpp, etc. ?

Thank you very much.

Regards,
Activecat

We wrote out own filters, which are specifically designed to work well
with the GNU Radio input/output buffers as well as use VOLK and other
tricks for speed. There are fir_filters_XXX that implement normal
convolution in time, but I would suggest you use the fft_filter_XXX
blocks, which perform fast convolution.

Tom