Precise interrupts in GNURADIO?

GNU Radio
1

Dear all,
In my application, I want to implement the following feature:
1. If I decode 50 packages, then stop the flowgraph immediately
2. otherwise, if after 30 seconds, I cannot receive more than 50
packages, then stop the flowgraph. So I could prevent the flowgraph from
locking forever.

  For the first part, I add a state machine inside the decoder. When

there are 50 packages decoded correctly, I would output a high level ‘1’
on
the output. Otherwise I output low level 0. I connect this output port,
with a probe. In python, I wrote
-------------------------------------------------------------
def _probe_peak_package_number():
while True:
val = round(self.probe_package_number.level())
if (val == 1):
print “package number reach threshold %d!”
%self.threshold
self.stop()
break
_probe_package_number_thread =
threading.Thread(target=_probe_peak_package_number)
_probe_package_number_thread.daemon = True
_probe_package_number_thread.start()
-------------------------------------------------------------
which starts a thread, listening to the probe. Whenever it observes a
high
level ‘1’, it would STOP the flowgraph immediately.

For the second part, I am using the Timer in the package threading.
-------------------------------------------------------------
#def _shut_down_flow_graph():
#print “Passing %d seconds, going to kill the process!”
%self.timing
#self.stop()

    #_timer_thread=Timer(self.timing,_shut_down_flow_graph)
    #_timer_thread.start()
 -------------------------------------------------------------

But, what I observe is that:

  1. If I set the threshold to 10 packages, I have to wait until about 100
    packages being decoded correctly. Sometimes I have to wait for about 500
    packages. The threading is not very stable, even there is an high-level
    output at the probe, it does not ‘see’ it immediately.

  2. The alarm would prevent my flowgraph from exiting. Namely, when there
    are more than 50 packages, the flowgraph would not be stopped, until 30
    seconds passed. But I have a self.stop() in the snippet.

             if (val == 1):
             print "package number reach threshold %d!"

%self.threshold
self.stop()
break

Why it does not terminate the python program immediately?

Or, is there any suggestions on implementing precise interrupt in
GNURADIO?

Thanks.

2

Precise timings like this are difficult to do with GNU Radio, which is
optimized for maximum throughput.

However, I think you can do things easier than you’re doing.
First of all, you can stop the flowgraph from within blocks by returning
WORK_DONE from your work function. You can also return WORK_DONE after a
timeout, but that may have some unintended effects, or maybe your work
function isn’t being called after the timeout.

However, you don’t necessarily need the probe.

On 02/09/2015 11:11 PM, Chen C. wrote:

But, what I observe is that:

  1. If I set the threshold to 10 packages, I have to wait until about 100
    packages being decoded correctly. Sometimes I have to wait for about 500
    packages. The threading is not very stable, even there is an high-level
    output at the probe, it does not ‘see’ it immediately.

You have little control over how data is processed, and it might happen
that GNU Radio pushes very large chunks of data through the blocks in
order to maximize throughput (thereby increasing latency).

Why it does not terminate the python program immediately?
I don’t fully understand what you’re trying to do here.

M