On Thursday, October 12, 2023 at 11:02:06 AM CDT, discuss-gnuradio-request@gnu.org <discuss-gnuradio-request@gnu.org> wrote:
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Today's Topics:
1. Some GRC files run with no errors but don't plot (tom sutherland)
2. Re: Some GRC files run with no errors but don't plot
(Marcus Müller)
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Message: 1
Date: Thu, 12 Oct 2023 11:36:24 +0000 (UTC)
Subject: Some GRC files run with no errors but don't plot
Content-Type: text/plain; charset="utf-8"
I have a simple grc file that shows the difference in Interpolation and Decimation using the Rational Re-sampler blocks. The program runs once, a "Time Sink" shows the signals(once) and then stops plotting and the Frequency Sink does not show a frequency plot at all. I've had other programs that do similar things, runs but nothing shows, once and freezes or for a few cycles and stops. Any thoughts on causes and /or how to solve/debug it would be appreciated. I am running GRC 3.10.5.0 on a Windows 10 Enterprise 12th Gen i7 machine with 32GB RAM. I've attached the grc/py and plot files.
Thanks...Tom
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Message: 2
Date: Thu, 12 Oct 2023 13:59:07 +0200
Subject: Re: Some GRC files run with no errors but don't plot
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I think I can explain!
Both sinks need to always consume the same number of input items from all their inputs.
So, even if you disabled the time sink, the upper sink would quickly grind to a halt,
because the "lowest rate" Rational Resampler (interp=1,decim=4) would not be able to
produce the samples needed to keep up with the "highest rate" resample (interp=4,
decim=1). Both resamplers work on the same input, just that the lowest-rate one takes 16×
the amount of input to produce the same amount of output as the highest-rate one. Since
both share the same input, and that input has a finite buffer, this can't work for long.
So, your flow graph has an architectural shortcoming, either way.
The time sink hits that bug you've built quicker, because it has no throttle in the way.
Best,
Marcus
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