Re: [Discuss-gnuradio] Visualizing Amplitude spectrum instead of power spectrum

Hey Fernando,

not quite sure I get what you need; I'd say the Amplitude Spectrum you'd be looking for is

or, rather, the decibel representation of that. There's no way to get a negative number out of the absolute of something – it's by definition a positive real number.

Now, we could also use our freedoms to define our amplitude spectrum to take the shape

But: that's really only useful if you have phase-coherent reception – as an analytic tool for an unsynchronized observation of the spectrum, it doesn't help you much, since you have a random due to having random relative phase.

So, maybe it'd be a good idea to formulate what purpose you're doing this for :) You can, indeed, tell 180° out-of-phase signals apart by this, but I'd argue that being 180° out-of-phase, for the most things I can think of, is only meaningful on one and the same frequency – and hence, I'm not quite sure this is what you're looking for!

Best regards,

Marcus

On 25.04.2017 12:01, Fernando wrote:

Hello.

Yes, with Time sink I can see the difference, but if the signal is compound of some other signals (for instance  signal=1K/amplitude +1 +2K/amplitude -1 +3K/qamplitude +1 +4K/amplitude +1 )  i would like to see the 2k signal as -1 amplitude, but in the power spectrum it will appear as possitive and in the QT time sink it is very difficult to see the signal as it is a complex one.

regards


El 25/04/17 a las 10:57, Jinyang Lee escribió:

Hello Fernando,

I think the QT GUI time sink displays the relationship between time and amplitude. You can see the signal through it. But when I use the channel model block,the QT2 can see the signal which is zero.

Enclose is running result with channel model and with channel model.

Regards,

Lee

2017-04-25 15:45 GMT+08:00 Fernando <fernando@samara.com.es>:

Hi.


Is there a way of visualizing ampitude spectrum (with + and - signals)
instead of power spectrum?


regards



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