calculate snr of digital signal

Hi I have a data stream say

data_in

Its maximum is data_max and min is data _min

means that data_in may vry between data_max and data_min

I need to calculate the snr of the data

I am doing it like this

diff=data_max-data_min;

SN=snr(data_in,diff);

Am I correct ??

Regards

Uzmeed

Answer 1

[Daniel M]

This is not correct. The second input to snr must be a real-valued row or column vector that must have the same dimensions as the first input. It is the estimate of noise of your signal. You are entering a single number which is the range of amplitudes of your signal.

How are you quantifying noise? What does your signal look like? You may want to browse the examples on the document page for snr to see if you can get an estimate of the noise that way. Otherwise, you'll have to provide more information here, perhaps in the form of a figure showing the frequency spectrum of your signal.

[Daniel M]

Also, you shouldn't name your variable diff as that overrides the native function diff. This is tricky for new users that don't know common MATLAB function names. If you're ever unsure, you can write

which <name>

where <name> is a variable you want to use, to check if it is the name of a function.

Answer 2

[uzmeed]

Thanks Daniel

All my input are cloumn vectors data_in is a single colum vector

similarly diff again a column vector that I am getting subtracting two column vectors data_min and data_max

As far as quantification of noise is concerned

I have digital stream of data with an RMS value ( I consider it as the signal)

Then have the min max limit till where the data can vary ( I cosider it the range of noise)

Suppose if the data_in =x;

data_min=0.9x;

and

data_min=1.1x

so I take 0.2x as noise, the diff of min max values

and calculate the snr as snr(data_in,diff)

Again thanks for guidance I will be carefull for assining variable

Best Regards

Uzmeed