Thank you for the tip, I have found this tool for easy FIR filter design: http://t-filter.engineerjs.com/ . What I am trying to achieve here is to get the same output signal from RFNoC FIR filter as I am currently getting from a design that is running purely on CPU using the low pass filter block in GNU radio. That block has the option to account a parameter called "decimation". Does anybody know how can I implement that parameter in RFNoC FIR filter block design?
Kind regards, Nives pon, 2. srp 2018. u 16:02 Marcus D. Leech <[email protected]> napisao je: > On 07/02/2018 07:33 AM, Nives Novković wrote: > > > Hi Marcus, > > Thank you for your answer, since I am quite new in this area I didn't > understand how to figure out which coefficients to enter. For example, if I > want to pass a signal only between 200 and 300 kHz, which coefficients > should I use? > > Kind regards, > Nives > > You'll need to use a filter design tool, like the FIRDES routines in Gnu > Radio, or the external filter designer or some other tool. > > > https://www.allaboutcircuits.com/technical-articles/finite-impulse-response-filter-design-by-windowing-part-i-concepts-and-rect/ > > > > > > --------------------------------------------------------------------------------------------------- > Message: 5 > Date: Tue, 19 Jun 2018 14:04:40 -0400 > From: "Marcus D. Leech" <[email protected]> > To: [email protected] > Subject: Re: [USRP-users] RFNoC FIR filter block - filter taps > Message-ID: <[email protected]> > Content-Type: text/plain; charset="utf-8"; Format="flowed" > > The RFNoC FIR filter takes a list of ints that can be scaled from a > floating-point representation of the filter. > > Gnu Radio includes the firdes routines for producing coefficients for > simple low-pass/high-pass/band-pass filters. One you have the results, > you can just use a simple Python expression to scale by 32767.0 and > convert to int. Something like: > > [int(i*32767) for i in filter_coeffs] > > Keep in mind that the RFNoC FIR filter is, last I checked, limited to 41 > filter coefficients > > On 06/19/2018 10:28 AM, Nives Novkovi? via USRP-users wrote: > > Hi everyone, > > > > me again with the questions. :) Next thing I am trying to learn is > > RFNoC FIR filter. I see that the only thing I can modify for the > > filter is filter taps. Is there any official documentation on those > > blocks? I am trying to figure out what values should I enter there if, > > i.e. I want to eliminate all the frequencies above 100 kHz. Those are > > actually coefficients in the FIR filter equation? Here is my current > > flow graph. > > > > > > fir_filter_flow_grc.png > > > > Kind regards, > > Nives > > > > > > >
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