Smooth a curve or increasing the resolution?

Hello !!

I read data from an instrument (ILX Lightwave TEC) that gives me current values and I plot against time, but my curve saturates at times. I think this might be a resolution problem.

I would like to smooth the curve.

I tried using the slidingavg function, but it doesn't seem right.

clear all
y = load('ILX_TEC_curr.txt');
x = load('ILX_TEC_time.txt');

N = 10;
ys = slidingavg(y, N);

hfig4=figure(4);
plot(x,y,x,ys,'-o');

xlabel('Time (s)','fontsize',18,'fontweight','bold');
ylabel('Sample TEC Current (A)','fontsize',18,'fontweight','bold');

Is there another form or function that can help me smooth the first result (first curve - blue line)?

Attached here are the data if that helps.

Thank you.

Tay

[Stephen23]

https://web.archive.org/web/20211124062931/https://www.mathworks.com/matlabcentral/answers/892372-smooth-a-curve-or-increasing-the-resolution

Answer 1

[Sulaymon Eshkabilov]

You may consider using a moving average filter smoothdata() with sgolay, for instance.

[Tay]

Hi Sulaymon Eshkabilov

Thanks.

Which would you be more advisable to use? Slidinggavg or smoothdata?

My data changes like rapid ramp.

For a window equal to 150, I got:

Thank you.

[Sulaymon Eshkabilov]

Before making a final decision, play with the settings of these filters and also test movmean(). And compare them. The problem here is the quality of your acquired data. It looks like your data was not collected on a fixed smapling time.

[Tay]

What do you mean by fixed sampling time?

I collect the current value each time using for loop.

Something like this

loop_end = 6000; 

for i = 1:loop_end
    ILX_TEC_time(i) = toc; %cpu elasped time
    ILX_TEC_curr(i) = str2double(query(ILX_obj,'TEC:ITE?')); %read ILX TEC current
end

Then I plot current x time aquired.

Will have a look to the movmean() function also :D