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Re: [Discuss-gnuradio] Change filter parameters in running flowgraph?


From: Adrian Hodgson
Subject: Re: [Discuss-gnuradio] Change filter parameters in running flowgraph?
Date: Thu, 02 Nov 2017 18:53:08 +0000

John you may be having a similar issue to the one I am having, have a look at 
the attached grc.

I find that if I start out at 100kHz bandwidth I can reduce and drop the 
bandwidth to 10kHz and then go back up again to 100KHz, the displayed 
bandwidth follows it. But if I set the default to start at the low end it does 
not increase.
The decimation and interpolation changes with the variable counters.

The flowchart is basically a narrow band radio receiver, I use hackrf one but 
it will work with a RTL2832.

Adrian



On Thursday, 2 November 2017 18:24:56 GMT John Ackermann N8UR wrote:
> OK, bummer but thanks for the clarification.
> 
> On 11/02/2017 01:58 PM, address@hidden wrote:
> > For the most part, decimation cannot be changed at runtime, due to the
> > way the scheduler does static allocation and buffer management.
> > 
> > On 2017-11-02 13:05, John Ackermann N8UR wrote:
> >> I'm getting ready to do a Gnuradio tutorial for a local group, and
> >> want to show the impact of decimation and filtering.  I created a QT
> >> Gui Range parameter that sets the ID "decimation".
> >> 
> >> In the low pass filter block I the decimation value is set to
> >> "decimation."  That seems to work and I can see the span of the QT
> >> Frequency Sink change as the decimation value changes.
> >> 
> >> But I also use the decimation parameter to determine the cutoff
> >> frequency ((samp_rate/decimation)/2) and transition width
> >> ((samp_rate/decimation)/10).  However, these don't seem to change
> >> dynamically when the flowgraph is running-- the filter remains at the
> >> width it was when the flowgraph started.
> >> 
> >> Is there a way to have the filter change as the decimation parameter
> >> changes?
> >> 
> >> Thanks,
> >> John
> >> 
> >> _______________________________________________
> >> Discuss-gnuradio mailing list
> >> address@hidden <mailto:address@hidden>
> >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> 
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Attachment: Narrow_band_QT.grc
Description: application/xml


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