Effect of having multiple throttle in a chain of flowgraph

GNU Radio
1

Hi,

I would like to ask what happen if there are many block of throttle
connected between a source and a sink in pure simulation? I notice the
GUI
Interface (wxgui) is getting slow when 5 throttle block is connected
between a signal source and signal probe sink.

| Signal Block | —> | Throttle | —> | Throttle | —> | Throttle | —>
| WX GUI Scope Sink |

2

On Tue, Jan 31, 2012 at 5:41 PM, محمد روسلي [email protected]
wrote:

–
Regards,
Muhammad b Rosli

It’s never been tested because there’s really no reason to ever do it.
You
only need one block that rate limits the flow graph. The throttle block
only exists if you are running things in simulation or without any real
hardware that controls the flow of data. It’s keeps the system from
consuming all of your CPU; especially useful when using GUIs.

Never use more than one rate-limiting block in your flowgraph.

Tom

3

On 1/31/12 5:41 PM, wrote:

Hi,

I would like to ask what happen if there are many block of throttle
connected between a source and a sink in pure simulation? I notice the
GUI Interface (wxgui) is getting slow when 5 throttle block is connected
between a signal source and signal probe sink.

| Signal Block | —> | Throttle | —> | Throttle | —> | Throttle |
—> | WX GUI Scope Sink |

The GUI slowing down is understandable. You’re doing a lot of extra
work for nothing. As Tom said, you only need one rate-limiting block
per flowgraph.

In addition to the extra work, you’re introducing a lot of extra latency
for no reason, because each interface introduces another 32k sample
buffer. This becomes particularly noticeable at low sample rates.

For example, at a sample rate of 9.6k, each 32k buffer introduces an
additional 3.1 SECONDS of latency! (1.04 ms/sample x 32k samples).

@(^.^)@ Ed