Proxmark3 community

iceman

Administrator

Registered: 2013-04-25

Posts: 9,538

Website

GUI Overlay functionality -LF - ASK only

"The overlays just allow different cleaning tools for ask modulation for now"

The overlay functionality is somewhat less documented. Its better that @marshmellow tells us how its suppose to work. I'm not quite sure myself.

They are however just GUI sliders calling the  autocorr, askedge, dirthreshold commands underneath. Once you have manipulated the signal to something that looks ok, you need to issue one of the "data rawdemod" commands to get the blue decoded signal as a overlay.

Signal colors

• green - raw signal

• red - demodulated ASK signal

• blue - decoded binary signal

marshmellow

Contributor

From: US

Registered: 2013-06-10

Posts: 2,302

Re: GUI Overlay functionality -LF - ASK only

the overlays window allows you to see the results of the ask cleaning commands `data askedge x` and `data dirthreshold x y` on the graph before applying the command so you can configure the correct value with the sliders.

once you are happy with it click apply. 

now you are ready to run a demod (i.e. `data rawdemod am`) 

if the results are not as expected click restore to undo the applied command.

the askedge and dirthreshold really only work with ASK based modulation NOT PSK or FSK.  once we build some FSK or PSK cleaning tools i will add them to the overlays.

the other MORE useful addition to the graph is the auto plotting of the demodulated data over the original graph of the signal in blue.  this works for all modulations.  (and is automatic)

the blue demod line allows you to learn how to demod the signal manually or understand what went wrong if it got the demod incorrect.

marshmellow

Contributor

From: US

Registered: 2013-06-10

Posts: 2,302

Re: GUI Overlay functionality -LF - ASK only

https://github.com/Proxmark/proxmark3/w … -new-graph
short demodulation walk through highlighting the demod (blue) line on the new graph.

ntk

Contributor

Registered: 2015-05-24

Posts: 701

Re: GUI Overlay functionality -LF - ASK only

This is an amazing work of art you have created here Marshmellow. It works very well on FSK, PSK traces... Strangely with ASK I have problem, I can not nail down yet, perhaps I need doing more training.

This tool is working very well, has helped me work out the relationship between graph and raw data. Thank you very much Marshmellow.

Still it makes me uneasy because of some reasons I think need to be clarify

But, before I post question I would like to apology to Marshmellow Gator96100 and all moderators who I have offended with my post#5 posted on 19/06/2017 in the thread lf guard no longer in V3.0.1.

For several weeks already  I have searched up and down internet for knowledge how to understand information from electric signal , graph, how to read the 1s and 0s from ASK/FSK/PSK graph. There are not much and contradicting material and when asked there is hardly a reply, it made me nervous, felt empty, scared being loaded with wrong worthless knowledge and  that made me crazy unbeareable to society... but those are no excuse for my wrong behaviour

I was very wrong on that evening. Pls accept my sincere apology.

marshmellow

Contributor

From: US

Registered: 2013-06-10

Posts: 2,302

Re: GUI Overlay functionality -LF - ASK only

with ask it is best to have a strong "clean" (or heavily clipped) wave.  with a weak wave the blue demod line may not line up as it should, yet the auto demod works.  there is a reason for this, but that gets a bit complicated. 

For best manual demoding (from the graph) a strong clean wave is needed.  this is the reason for the dirthreshold and askedge functions - different tools that might clean up the wave.  but they might also destroy it depending on the settings.  this is the reason for the overlays window, to allow you to try different settings on those tools and see how it will affect the original wave if you apply it before you actually do.  and you can revert it easily if it doesn't work to try again...

once you have a strong wave and run a demod cmd then the blue lines should line up appropriately.

marshmellow

Contributor

From: US

Registered: 2013-06-10

Posts: 2,302

Re: GUI Overlay functionality -LF - ASK only

also when looking at various graphs of modulating waves from different devices (like PM3 vs scope) you have to understand the sample rate the graph is taken at.  different sample rates and different min and max amplitudes can drastically change the look of the same wave at the same frequency.

iceman

Administrator

Registered: 2013-04-25

Posts: 9,538

Website

Re: GUI Overlay functionality -LF - ASK only

..it took me some time to understand what a heavily clipped wave was in the beginning.

For those who doesn't know yet, its a wave with the "top"/"bottom" cut off.  No round nice curve, just cut off.