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regarding correlation and cross-correlation

Started by Unknown March 4, 2008
Hi,
 this is devika , i want some  clear information regarding the
correlation and cross-correlation .
    if there are two sine waves  how can we see taht they are
correlated and cross-correlated .
please give some examples with there wave forms  examples   and give
some information regarding how to calculate the correlation and cross-
correlation as per  equations(software view)
please reply as early as possible
 waiting for u r reply ,

 thanks&regards,
 Devikareddy.
devikapatnam@gmail.com wrote:
> Hi, > this is devika , i want some clear information regarding the > correlation and cross-correlation . > if there are two sine waves how can we see taht they are > correlated and cross-correlated . > please give some examples with there wave forms examples and give > some information regarding how to calculate the correlation and cross- > correlation as per equations(software view) > please reply as early as possible > waiting for u r reply , > > thanks&regards, > Devikareddy.
May I suggest starting at http://en.wikipedia.org/wiki/Cross-correlation
On Mar 4, 6:42 pm, Richard Owlett <rowl...@atlascomm.net> wrote:
> devikapat...@gmail.com wrote: > > Hi, > > this is devika , i want some clear information regarding the > > correlation and cross-correlation . > > if there are two sine waves how can we see taht they are > > correlated and cross-correlated . > > please give some examples with there wave forms examples and give > > some information regarding how to calculate the correlation and cross- > > correlation as per equations(software view) > > please reply as early as possible > > waiting for u r reply , > > > thanks&regards, > > Devikareddy. > > May I suggest starting athttp://en.wikipedia.org/wiki/Cross-correlation
hi devika, try out hands at matlab functions of xcorr and remember you try to see the xcorr code by typing edit xcorr in the command window and you can come to know about it. particle (filter) reddy
Hi,

    we are not using the  matlab functions , we have to write code in
embedded C only that why iam asking you. and we have to do calculation
in that why if you have information regarding this please provide me .
waiting for your reply.


Thanks&regards,
Devika.

On Mar 4, 9:22&#2013266080;pm, "PARTICLEREDDY (STRAYDOG)"
<particlere...@gmail.com> wrote:
> On Mar 4, 6:42 pm, Richard Owlett <rowl...@atlascomm.net> wrote: > > > > > > > devikapat...@gmail.com wrote: > > > Hi, > > > &#2013266080;this is devika , i want some &#2013266080;clear information regarding the > > > correlation and cross-correlation . > > > &#2013266080; &#2013266080; if there are two sine waves &#2013266080;how can we see taht they are > > > correlated and cross-correlated . > > > please give some examples with there wave forms &#2013266080;examples &#2013266080; and give > > > some information regarding how to calculate the correlation and cross- > > > correlation as per &#2013266080;equations(software view) > > > please reply as early as possible > > > &#2013266080;waiting for u r reply , > > > > &#2013266080;thanks&regards, > > > &#2013266080;Devikareddy. > > > May I suggest starting athttp://en.wikipedia.org/wiki/Cross-correlation > > hi devika, > &#2013266080; &#2013266080; &#2013266080; &#2013266080; &#2013266080; &#2013266080; &#2013266080; try out hands at matlab functions of xcorr and > remember you try to see the xcorr code by typing &#2013266080;edit xcorr &#2013266080;in the > command window and you can come to know about it. > > particle (filter) reddy- Hide quoted text - > > - Show quoted text -
devikapatnam@gmail.com wrote:
> Hi, > > we are not using the matlab functions , we have to write code in > embedded C only that why iam asking you. and we have to do calculation > in that why if you have information regarding this please provide me . > waiting for your reply. > > > Thanks&regards, > Devika.
To help get the feel for how correlation works, you might want to set up an experiment in a spreadsheet. For example: - Set up two pairs column, where each pair represents a sine of a certain frequency and phase. The first column of each pair is the phase angle; the second is the cosine of the first. - Add a cell at the top of each phase column that allows you to parameterize the change in phase per cell. - Make another column that's the product of the two cosine columns and total up the product column using the "sum" function. - Experiment with different initial phases and delta-phases (frequencies) and see how the sum changes. You can expand this to cover the case of a complex signal (that is, a cosine/sine pair) by adding in a sine column for each signal and calculating the product according to the rules of complex numbers. Also, be sure to conjugate the second one by negating its sine column. Once you master all that, you're well on your way to writing your own correlation routines in C. Basically, correlation boils down to multiplying corresponding data points from two signals and summing the result. You can implement it by translating the formulas in textbooks directly into code - or a spreadsheet. =g2 _____________________________________________________________________ Grant R. Griffin Publisher of dspGuru http://www.dspguru.com Iowegian International Corporation http://www.iowegian.com See http://www.iowegian.com/img/contact.gif for e-mail address
Hello Devika,

      The equation for autocorrelation and cross-correlation are
      very simple and mentioned at many websites and standard DSP
      textbooks (buy DSP book by proakis and manolakis, 
      one of the best book written in the subject of DSP).

      The equation is also very easy to implement. 
      You just need to run a for-loop. In embedded application 
      not sure if for-loop is better or their are more efficient ways.
      This you may check with local embedded C expert.

      In case if you do not have access to Matlab, you can 
      use Octave or Scilab (both these softwares are free and both
      of them have windows and linux versions, easily downloadable
      and installable from their websites www.octave.org and 
      www.scilab.org. I am big time fan of Octave (Million Thanks to 
      John W Eaton and his team) and do not use Matlab at all. Matlab
      license cost is 3 lakh Rupees in India
      (basic matlab + signal processing toolbox + image processing
      toolbox). Also I have build up my own DSP function library
      in octave to make it superior to Matlab for signal processing
      applications.

      You may write your efficient code in embedded C but to test it
      you can use functions available in scilab and octave. My suggestion
      is use Octave as it is more matlab compatible and easy to use. The
      code can be ported vice-versa without extra effort.

Regards
Bharat Pathak

Arithos Designs
www.Arithos.com