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From: | Ron Economos |
Subject: | Re: [Discuss-gnuradio] DVB-S2 Physical Layer Framer: Why outputs a zero after each sample? |
Date: | Wed, 15 Jun 2016 15:41:02 -0700 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 |
The primary design decision was to use the FFT filter instead of the
interpolating FIR filter for performance. The FFT filter is
considerably faster, especially at the 100 taps used in the flow
graph. However, (as far as I know) the FFT filter does not have an
interpolation option, just decimation. So the 2X interpolation is
done in the Physical Layer Framer block instead. You can remove the zero stuffing from the Physical Layer Framer and use the Interpolating FIR Filter block instead of the FFT filter block for RRC filtering. If you try that, be sure to remove the factor of two in lines 535, 548 and 680 in the PL framer block. Here's a link that explains why zero stuffing is the correct way to do interpolation. http://www.dspguru.com/dsp/faqs/multirate/interpolation Ron On 06/15/2016 02:37 PM, Francisco
Albani wrote:
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