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From: | Marcus Müller |
Subject: | Re: [Discuss-gnuradio] Processing expectations |
Date: | Mon, 10 Aug 2015 14:14:04 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
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. Best regards, Marcus [1] https://github.com/gnuradio/gnuradio/blob/master/gr-filter/python/filter/rational_resampler.py On 10.08.2015 13:55, Tom Cook wrote:
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