Hi Tom, added the block, opened the block properties, had a look at the id; I knew that these kind of blocks live within gr-filter, so
cd gr-filter vim grc/*rational*.grc ##that's where the block definitions for GRC reside found out that the non-base variant used rational_resampler_$(type), but I had a look into filter, and only found rational_resampler_base_*; so I guessed it was a python file. Went into python/filter, and opened rational_resampler.py, based on it being the only python file that was possibly relevant here. You know, that's really unintuitive, and I think we'll need some helpers or better documentation that makes finding such things easier. Best regards, Marcus On 10.08.2015 14:31, Tom Cook wrote: > On Mon, 10 Aug 2015 at 13:14 Marcus Müller <marcus.muel...@ettus.com > <mailto:marcus.muel...@ettus.com>> wrote: > > Hi Tom, > > I just had to look this up. If you're in GRC, you have "rationale > resampler" and "rational resampler base"; they do basically the > same, but if you use the one without "base", and don't specify the > taps, GNU Radio just automatically designs a filter that avoids > all aliasing and imaging, which is done with a python wrapper > around the C++ rational_resampler_base_xxx's make function[1]. > That's pretty handy in most use cases, but not too much if you > want your own filter for some reason. > > If you're using the "base" variant, you /must/ specify the taps > yourself, because you directly invoke the C++ block's maker. If > you go ahead and just use "[1.0]" as taps, you get the aliased > results from my pictures. > > So if you happen to /want /to specify the taps, because you can > integrate the functionality of a downstream filter into the > resampler to save CPU cycles, it doesn't make a difference which > block you use. > > > Ah, I see. Many thanks for taking the time to explain this. Where > did you look to find out that 'rational resampler' block does an > automatic filter design for you? > > Regards, > Tom
_______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
