Re: [Discuss-gnuradio] GRC, Recording chunks of spectrum triggered on input signal level

[Marcus D. Leech]

On 11/18/2014 04:17 PM, Staffan Bruce wrote:
> It works, many thanks!
>
> It seems like the changing of a variable in itself does not trigger an 
> update of other variables (that are depending on the first one), but 
> using a button or probe will trigger an update of the variables that 
> are depending on them. Could this be something to consider for 
> GnuRadio/Companion, i.e., dependencies between variables and assuring 
> that they are updated when a change is occurring in one of them?
The dependency tree in GRC *does* work, but not "backwards".  If b 
depends on a, and a changes, b will be updated, but not the other way 
around.


> Still, file sink notices the change of the variable it is depending on 
> and that is enough. Now I have a good way of making separate 
> recordings - great!
>
> ...and yes - time to start learning how to code.
I will point out, gently, that this is *software* defined radio, rather 
than, for example, interpretive-dance defined radio.  So going into it 
expecting
  to never have to actually "code" anything is a rather naive.  The GRC 
"Lego(tm)-like" model can, realistically, only take you so far.  For 
one, it has
  a data-flow model, so doing "algorithmic" things requires that you 
escape from that model, which lands you smack in the middle of 
fairly-conventional
  software development...




> Regards,
>  Staffan
>
> -----Original Message----- From: madengr
> Sent: Monday, November 17, 2014 6:58 PM
> To: address@hidden
> Subject: Re: [Discuss-gnuradio] GRC, Recording chunks of spectrum 
> triggered on input signal level
>
> If you are using an "if" statement to switch between filename and 
> /dev/null,
> try putting the filename construction in the "if" statement, instead of a
> separate variable.  That may make it evaluate every time the "if" 
> statement
> is called.
>
> My example used the LO frequency as part of the filename, and every 
> time the
> QT GUI slider changed the LO, it probably updated the filename.
>
> If that does not work, maybe you can use a probe to examine a signal, say
> 10x a second.  Then the probe level() function could be used as part 
> of the
> filename.  That would at least change it 10x a second.
>
> For the counter, maybe you could also use a probes to look at a signal
> before and after a N sample delay, where delay and sample rate is 
> about the
> same time as your probe rate; then this pseudocode:
>
> if now.level() != delayed.level() then count = count +1
>
> At this point though you ought to delve into the Python.  As long as 
> you are
> not using the QT GUI, the code is pretty straight forward.  You can use
> probes to pull values out of the flow and evaluate them in Python.
>
> Thanks,
> Lou
> KD4HSO
>
>
>
>
> Staffan wrote
> > Hello,
> >
> > After some weekend experimenting I believe I have most (most...) of it
> > working. Sinking to a USB stick is not working so well by the way...
> > One thing that is still a challenge is how to set the filename. You
> > provided
> > a very good way of timestamping, but when I try this, it only evaluates
> > once - when I start the script. Is there any way to force 
> > re-evaluation of
> > a
> > variable?
> > In addition, it would be great to have some kind of a counter 
> > (variable, x
> > =
> > x + 1) that can be updated depending on a state change - for example 
> > when
> > a
> > trigger event occurrs. I tried some different versions, but mainly ended
> > up
> > in circular references...
> >
> > Any suggestions would be highly appreciated!
> >
> > Regards,
> >   Staffan
>
>
>
>
>
> --
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> Sent from the GnuRadio mailing list archive at Nabble.com.
>
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--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org