Hi, Le 22/10/2013 19:14, Todd a écrit : > > Thanks for the feedback. I agree that your documentation does make > clear the distinction between "phase" and "angle" and that it has > a consistency. I just feel that this distinction does not exist > "outside" ... > > But beyond this question of phase vs. angle, I must say I don't > see that big a use case for phase/angle spectrums[*] (as opposed > to magnitude which are much used). > > > I personally use phase and angle spectrums a huge amount. In signal > processing it is extremely important. It is a critical component in > acoustics. It is also used a lot to separate out signals that have > been mixed together. Knowing the phases of signals can also be very > important in certain optics applications and for radio signals and > RADAR. Changes in the phase spectrum over time (like you would get > from a phase spectrogram) is important for doppler analysis both with > optical and acoustic signals. > > Also, from an educational perspective, anyone taking a digital signal > processing course will need to produce magnitude/phase plots, probably > both with and without wrapping (since any decent digital signal > processing course will teach you about the pitfalls that occur due to > phase wrapping). So this will make matplotlib much more useful for > such courses. > > > Also, in many cases, "spectrum" is synonymous with spectral > density, which implies "magnitude". In the end I wonder whether > the notion of phase even makes sense for a spectrogram ? > > > Yes, particularly electrical engineering. But there are many other > fields where spectral density is rarely used, and where more > "ordinary" magnitude and phase plots are the norm, as I explained in > the previous paragraphs. Thanks for dealing with my ignorance. It's true that I have a biased view on these frequency functions, because I mostly deal with random signals these days.
In fact I'd like to understand a bit more how phase spectorgram works. Since the signal must be cut into chunks to make the plot along time, how is the phase computations "synchronised", that is, how does it use a common time reference. (because I would imagine that otherwise the phase would make "jumps" between each window frame). Do you have a pointer for how this is solved ? (or is this problem just non-existing?). best, Pierre
signature.asc
Description: OpenPGP digital signature
------------------------------------------------------------------------------ October Webinars: Code for Performance Free Intel webinars can help you accelerate application performance. Explore tips for MPI, OpenMP, advanced profiling, and more. Get the most from the latest Intel processors and coprocessors. See abstracts and register > http://pubads.g.doubleclick.net/gampad/clk?id=60135991&iu=/4140/ostg.clktrk
_______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
