Re: [Discuss-gnuradio] Multirate Blocks

On Sat, Feb 26, 2011 at 8:00 AM, Antoine Dedave <qlmqny_anti_rsca@hotmail.com> wrote:

Hi,

I'm implementing a 2-FSK modulator (I Know that a good one already exists but 

i have to do it myself for academic purpose). 

To do so, i produce a given (N) number of samples corresponding to the sampling of a complex exponnetial for each

 incoming bits.

 

The "sampling rate" (one bit => N samples) is increased  by N through the modulator, so i'm doing this

 

Constructor:

  

  set_relative_rate(N);

  set_output_multiple(N);

  

General_work:

  

  consume_each(noutput_items/N);

  

Is that correct? and is there anything else to do? 

Thanks in advance,

Antoine Dedave

First, what type of gr_block are you inheriting from? The fact that you are using noutput_items/N in your consume_each function makes it look almost like you are using a gr_sync_block, which would not be the right answer here.

In fact, you can use a gr_sync_interpolator since you know the direct relationship between input and output samples (1-to-N). Set the interpolation rate as N and you don't need to worry about any of the reset (setting the relative_rate or consume_each; the parent class knows what to do with them).

Look at the implementation of gr_sync_interpolator to see how it handles setting everything up for you to do the interpolation properly.

Tom