Re: [Discuss-gnuradio] External library for low pass filtering

[Tom Rondeau]

On Sat, Jan 25, 2014 at 10:46 AM, Activecat <address@hidden> wrote:
> 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

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