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I am plotting SNR ~ BER with a limited number of points i.e I have 2 series of data [x] and [y]

Now I want to make it a smooth curve of the plot(x,y) (just like in Excel). Anyone know how to do that?

Thanks alot!

HTH

FROM HELP:

p = polyfit(x,y,n) finds the coefficients of a polynomial p(x) of

degree n that fits the data, p(x(i)) to y(i), in a least squares

sense. The result p is a row vector of length n+1 containing the

polynomial coefficients in descending powers.....

I hope this will answer your question!

Regards,

Sohaib.

--- In matlab@matl..., Heart To Heart <heart2heart090@y...>

wrote:

> Hello,

> I am plotting SNR ~ BER with a limited number of points i.e I have

2 series of data [x] and [y]

> Now I want to make it a smooth curve of the plot(x,y) (just like

in Excel). Anyone know how to do that?

> Thanks alot!

>

> HTH

> I am plotting SNR ~ BER with a limited number of points i.e I have

> 2 series of data [x] and [y]

> Now I want to make it a smooth curve of the plot(x,y) (just like in

> Excel).

The smoothing in Excel is made via splines: you take 3rd degree

polynomials, and adjust their four coefficients with the need of

continuity, and smooth 1st and 2nd order derivatives. Then you would

have to create sufficient points from those polynomials, so that you

can see the curve really smoothed.

MATLAB implements the spline command.

Try "help spline" to see how it works.

--

Juan de Dios Santander Vela

BS in Physics, Master in Electronic Engineering

D.Sc. Student on Multimedia Technologies

Instituto de Astrofísica de Andalucía — Pre-doctoral Contract

Hi there,

SNR values are usually presented in dB. So you scale should be in
logarithmetic scale. Here you have to use semilogxy function instead of
plot(x,y), check the function with help.

To get smoother curves you suppose that you have two values of SNR:

1- the one with dB values SNR1=1,2,3,.....20,...

2-SNR2^((SNR1)/10)

in your Gaussian noise formula use the values of SNR2 and then you will get smmother curves.

in your Gaussian noise formula use the values of SNR2 and then you will get smmother curves.

regards

khmaies

Thanks guys for your advice, finally, it is done with just 3 commands below.

Cheers,

HTH

1. polycoefficient = polyfit(EbN0db,log10(ber_itn+10^(-30)),2);

%Find the coefficents of a polynomial of order 2

% to approximate log10(ber) of each iteration

%10^(-30) to make ber_itn non-zero

2. poly_ber = 10.^polyval(polycoefficient,EbN0db);

%Approximate log10(ber) of each iteration using the above coefficents

3. semilogy(EbN0db,poly_ber,'-',EbN0db,ber_itn,'+'); grid on

%plot both actual data and approximated data

hold on; khmaies ouahada <khmaies@khma...> wrote:

Hi there,

SNR values are usually presented in dB. So you scale should be in logarithmetic scale. Here you have to use semilogxy function instead of plot(x,y), check the function with help.

To get smoother curves you suppose that you have two values of SNR:

1- the one with dB values SNR1=1,2,3,.....20,...

2-SNR2^((SNR1)/10)

in your Gaussian noise formula use the values of SNR2 and then you will get smmother curves.

regards

khmaies

To

___________________________________________________________

If I have 3 letters: H, R, T.

I can add E, A to have HEART,

I can also add U to get HURT.

But:

I'd rather have U and get HURT than having a HEART without U __________________________________________________

">http://mail.yahoo.com

Hi!

Great to see the solution also, other wise most of the time, only problems
where seen & no solution, after long time. Thanks Heart to share the
solution.

Regards,

Sohaib.

*Heart To Heart <h...@yahoo.com>*
wrote:

Hello,

Thanks guys for your advice, finally, it is done with just 3 commands below.

Cheers,

HTH

1. polycoefficient = polyfit(EbN0db,log10(ber_itn+10^(-30)),2);

%Find the coefficents of a polynomial of order 2

% to approximate log10(ber) of each iteration

%10^(-30) to make ber_itn non-zero

2. poly_ber = 10.^polyval(polycoefficient,EbN0db);

%Approximate log10(ber) of each iteration using the above coefficents

3. semilogy(EbN0db,poly_ber,'-',EbN0db,ber_itn,'+'); grid on

%plot both actual data and approximated data

hold on;khmaies ouahada <k...@gmail.com> wrote:

Hi there,

SNR values are usually presented in dB. So you scale should be in logarithmetic scale. Here you have to use semilogxy function instead of plot(x,y), check the function with help.

To get smoother curves you suppose that you have two values of SNR:

1- the one with dB values SNR1=1,2,3,.....20,...

2-SNR2^((SNR1)/10)

in your Gaussian noise formula use the values of SNR2 and then you will get smmother curves.

regards

khmaies

To

___________________________________________________________

If I have 3 letters: H, R, T.

I can add E, A to have HEART,

I can also add U to get HURT. &nb sp;

But:

I'd rather have U and get HURT than having a HEART without U__________________________________________________

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