Re: QT GUI Time Sink graph refresh rate

[Cyrille Morin]

Hi Marcin,
In this graph, the Time sink waits for chunks of 100 samples to display at a time.
Since the Throttle is set to forward 1000 samples per second, it should be able to update up to 10 times per second. 

Keep in mind that this is an estimate since the Throttle block does not enforce its timing exactly. It depends on the size of sample blocks it operates on. 
So it could be possible that the scheduler gives it a chunk of 1000 samples at a time. In this case, it would forward it whole, and the Time sink would only display the 100 samples out of these 1000. 
If that repeats, you would only get 1 update per second.

Hope this makes sense,
Cyrille

Le 30 décembre 2021 10:38:06 GMT+01:00, "Marcin Puchlik via GNU Radio, the Free & Open-Source Toolkit for Software Radio" <discuss-gnuradio@gnu.org> a écrit :

Hi Marcus,

Thanks for your answer. Please, check out this flowgraph.

Shouldn't the Time Sink update its graph content every second in this configuration?

https://gist.github.com/marcinsztajn/224ced2e1b3921aa97ef28978c1b8426

BR,

Marcin

śr., 29 gru 2021 o 19:27 Marcus Müller <mmueller@gnuradio.org> napisał(a):

Hi Marcin,

only if there's no other component that limits the speed of processing. For example, if
the samples come from an SDR, than that has a sampling rate, so there's only so many
samples per second that can reach your sink.

 > I noticed that when I am using
 > throttle block along with QT GUI Time Sink the update period is not working properly (I
 > have to wait much longer to see the updated graph).

That only happens when the number of samples reaching the sink isn't sufficient to get one
full vector of samples per update period.

Best regards,
Marcus