Re: Vector Source and QT GUI Time Sink causes performance drop

[Ron Economos]

It's telling you what's wrong.

>>> Warning: This flow graph may not have flow control: no audio or RF hardware blocks found. Add a Misc->Throttle block to your flow graph to avoid CPU congestion.

Add a Throttle block between the Vector Source and QT GUI Time Sink blocks.

Ron

On 1/9/21 14:32, Mariusz Pluciński wrote:

Hello everybody,

I'm quite new to GNU Radio (and to signal processing as well), but I did a few successful experimens. But now, I encountered a weird behavior, namely:

Every flowgraph including Vector Source and QT GUI Time Sink conencted (regardless if directly or with intermediate steps) causes huge performance degradation. CPU usage jumps to 100% of a core, window takes a few seconds to refresh, GUI becomes almost unusable.

Everything works well if I use any different source, .e.g. Signal Source or osmocom Source.

Everything works well if I use any different sink, e.g. Audio Sink or QT GUI Frequency Sink.

It's just this specific combination that causes the issue. Drastically reducing the number of points in the Time Sink helps, but at the cost of the output becoming useless.

To reproduce the problem, it's enough to do the following in GNU Radio Companion:

1. Create an empty flow graph

2. Add "Vector Source"

3. Change "Vector" parameter to "(0, 0, 0, 1)"

4. Add "QT GUI Time Sink"

5. Connect both blocks

6. Run

Am I doing something wrong here?

(in case it's necessary, my ultimate goal here is to use the vector source as a source of bits to modulate a square wave; the output will later be transmitted out, but first, I'd like to see it in the Time Sink)

I'm using GNU Radio 3.8.1.0 on Ubuntu 20.04.

Best Regards,

Mariusz Plucinski