Hi. Yes. I am just looking at modeling a class-B distortion at the moment, but could someone guide on how to convert between quadrature signals and real signals. Because the rail (or the other one I was trying .. abs, only work on real signals)
The simple example im trying to shoot for is create a wbfm waveform, "clip/distort" it, and demodulate it and see the noise in the spectrum. Thanks for the replies!! :) On Wed, Jan 26, 2022 at 1:55 AM Nick Foster <bistrom...@gmail.com> wrote: > Anish, > > If you really just want to model crossover distortion in a class-B > amplifier, you could use a pair of Rail blocks: > [image: image.png] > > If you're trying to model the distortion created by a real solid-state > amplifier, and not trying to correct it with predistortion, there are a > million different models which attempt to accurately characterize > distortion in SSPAs: Rapp, Saleh, and Ghorbani seem to be most widely used. > They're all pretty simple. > > Here's a very simple, memoryless model (Ghorbani) implemented as an > embedded Python block: > https://gist.github.com/bistromath/75d30dd9691fd18211b306db630d8c4f > > Some basic information about the model can be found here: > https://www.mathworks.com/help/comm/ref/memorylessnonlinearity.html > > Nick > > On Tue, Jan 25, 2022 at 12:03 PM Wheberth Damascena Dias < > whebe...@gmail.com> wrote: > >> Hello Anish, >> >> Non-linear power amplifier modeling and pre-distortion is a vast subject. >> >> If you want to go deep in this matter I would suggest you to take a look >> at Baseband polinomial models. >> Here a reference I have used some time ago: >> https://repositum.tuwien.at/handle/20.500.12708/13980 >> >> If you just need something quick, you may want to lookout for AM/PM >> models, such as the Saleh model. >> >> Good luck! >> >> Best Regards >> Wheberth Dias >> >> >> >> >> On Tue, Jan 25, 2022, 20:44 Anish Mangal <anis...@umich.edu> wrote: >> >>> Hi, >>> >>> How should I go about modeling the distortion introduced by a class-B >>> amplifier stage that clips the signal when its value is below zero? >>> >>> Example: >>> >>> I want to combine two FM modulated signals, pass them through this >>> "class-B distorter", demodulate them, and analyze the quality of the signal >>> produced (compared with the undistorted one). >>> >>> How should I go about doing it. >>> >>> Created the flowgraph attached, but this is obviously wrong. :) >>> >>> -- >>> Anish >>> >>> >>> >>> >>> -- Anish
