find the dependence ratio

2 views (last 30 days)
hi, i have a graph above. Now i want to comment in this graph. For example, if the channels increase 4 times, the OSNR decrease 'x' times. What function should i use to find 'x'?

Accepted Answer

Salaheddin Hosseinzadeh
Salaheddin Hosseinzadeh on 29 Aug 2014
Dear Son,
You can make a function if you have a series of measurements.
You can compare results with a base signal, and then find a equation for it using cftool
Lets say channel(ch) = 2 then OSNR reduced 1
ch = 3, ONSR = 2
ch = 4, OSNR = 3
and so on
What you need to do is then go to the cftool
then assign the x and y data
x is the ch
y is the OSNR
Find a fit for it, whichever method you prefer.
Then you have an equation or relation between ch and OSNR which allows you to predict and tell the dependency of CH and OSNR.
Hope this helps
Good Luck!
Salaheddin Hosseinzadeh
Salaheddin Hosseinzadeh on 29 Aug 2014
That's good Son,
So you managed to find a polynomial fit with max degree of 2
That's great, congradulations.
Now you have the equation which is
f(X) = (-14.74)X^2 + 5.23X + 5.431
Where x is I guess number of channels

Sign in to comment.

More Answers (1)

Salaheddin Hosseinzadeh
Salaheddin Hosseinzadeh on 29 Aug 2014
Hi Son,
I guess you want to compare between your signals to see how close the are! At least that what I understood from your unclear question.
To see this you need to use Xcorr I believe to see the correlation between your signals.
To find the corss correlation in MATLAB you can either use crosscorr function or xcorr
doc crosscorr
doc xcorr
type those above in MATLAB to see the matlab documentation about them, they are straightforward to use.
If this is not what you're looking for just let us know.
Good Luck.
son on 29 Aug 2014
yeah, but i want to find a function to show this dependence. is it possible?
if i know that function, i can find the OSNR decrease for the number of channels increase 2.5 WITHOUT plot a graph.

Sign in to comment.


Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!