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] <mailto:[email protected]>>
To: [email protected] <mailto:[email protected]>
Subject: Re: [USRP-users] RFNoC FIR filter block - filter taps
Message-ID: <[email protected]
<mailto:[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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