Re: [Discuss-gnuradio] AWAL root raised cosine filter in the GRC trunk?

[Johnathan Corgan]

On Fri, Dec 12, 2008 at 1:47 PM, Josh Blum <address@hidden> wrote:

> However, I would like to make these convenience blocks for some of the
> combinations. Would RRC FIR be useful? Any other suggestions for some
> practical combinations?

A rational resampler that used RRC taps would be useful as a transmit
side RRC interpolator.

A common MPSK transmitter chain is to create a symbol stream at a
particular number of samples per symbol (related to your input data),
perform RRC filtering, then resample to meet the rate expected by the
USRP at some particular hardware interpolation rate.

You can economize CPU cycles by merging the RRC and resampling filter
stages, that is, by using properly calculated RRC taps in the place of
the resampler lowpass filter.

You could make a GRC wrapper for this.  Come to think of it, this
would be a good opportunity to make a hierarchical block for the blks2
namespace.

-Johnathan