I think perhaps reversing the phase (when negative) and adding/subtracting it from the original (equivalent of rail) might create a class-B type distortion perhaps?
Documented my experiments with a grc flowgraph and video.. Thoughts? https://www.youtube.com/watch?v=t3BxxEtTPJs 2 grc files are hierarchical blocks and one is the actual flowgraph On Wed, Jan 26, 2022 at 2:31 AM Anish Mangal <anis...@umich.edu> wrote: > 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 > > > > -- Anish
class_b_distort.grc
Description: application/gnuradio-grc
wbfm_carrier_block.grc
Description: application/gnuradio-grc
class_b_odd_imd_multi_carrier.grc
Description: application/gnuradio-grc
