Re: [Discuss-gnuradio] Calculate signal deviation in gnuradio

[Roman]

Marcus, many thanks again!

It seems that I am on the right way, at least with calculations. :)

Lets continue with your thought-provoking questions.

" Is your received signal real-valued?" No, I put the "complex-to-mag" block before.

Regarding the final goal.

I would like to evaluate the channel characteristics for the same bursty packet signal in channels with different propagation characteristics.

For example in environment with multipath propagation will cause signal fading (at least, it should). I would like to evaluate how deep the fading is by calculating the variance of the received signal level.

Is it a right approach?

Or can you advise better alternatives of using gnuradio for such purpose?

Reards,

Roman

 

On Wed, Mar 14, 2018 at 12:21 AM, Müller, Marcus (CEL) <address@hidden> wrote:

Hi Roman,

well, it's a short term sample variance, indeed.
Is your received signal real-valued? That's surprising me a bit!
I don't think "variance per packet" is really a meaningful thing to
say. If we're talking proper variance, that's a property of a Random
Variable, not of some short observation of a short signal. I'd be
willing to say that, since variance is the same as power for
theoretically infinitely long signal, and energy is the same (or, at
least, proportional) to sample variance of a short observation, that
you're looking for the energy in a packet. Is that right?

Maybe you could give us a bit of a feeling what you're trying to do by
calculating the variance?

Best regards,
Marcus

On Tue, 2018-03-13 at 23:20 +0300, Roman wrote:
> Marcus, great thanks for reply!
> Is attached flowgraph a good approach to the variance calculation?
>
> What should I do in case of bursty signals? Can I calculate signal variance per packet?
>
> Regards,
> Roman
>
> On Tue, Mar 6, 2018 at 4:57 PM, Müller, Marcus (CEL) <address@hidden> wrote:
> > You can definitely do that! In fact, it's pretty easy. Really, read the
> > tutorials I've linked to, and you'll quickly get an idea what to do
> > when you want a moving average of the power of a signal (namely,
> > convert it to it's magnitude², then apply a moving average), and once
> > you have that, it's really only building basic math to calculate the
> > variance :)
> >
> > GNU Radio comes both with the possibility to interface with SDR
> > hardware, so that you can assess real-world signals and propagations,
> > as well as with several channel models that you can use to simulate.
> >
> > Best regards,
> > Marcus
> >
> > On Tue, 2018-03-06 at 16:50 +0300, Roman wrote:
> > > Marcus,
> > >
> > > Sorry for confusion, language problem.
> > > I would like to calculate first and second statistical moments (mean and variance) for received signal level.
> > >
> > > Regards,
> > > Roman
> > >
> > > On Tuesday, March 6, 2018, Müller, Marcus (CEL) <address@hidden> wrote:
> > > > Hi Roman,
> > > >
> > > > probably, it's possible, but I have no idea what you mean with "signal
> > > > deviation". Maybe you could elaborate?
> > > >
> > > > To give you a quick look into what GNU Radio can do for you: see https:
> > > > //tutorials.gnuradio.org
> > > >
> > > > Happy signal processing,
> > > > Marcus
> > > > On Tue, 2018-03-06 at 08:50 +0300, Roman wrote:
> > > > > Hi group,
> > > > >
> > > > > I would like to evaluate the signal deviation in different propagation conditions. Is there a way to calculate this in gnuradio or should I export data for further external processing?
> > > > > Thanks for replying!
> > > > > Roman
> > > > > _______________________________________________
> > > > > Discuss-gnuradio mailing list
> > > > > address@hidden
> > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>