extract and change fundamental frequency

I have a sin wave,the fundamental frequency of sin wave is 50 Hz & it contains harmonics(3rd order & 5Th order)the frequency of 50 Hz is continued till 5 sec and at 5 sec the fundamental frequency that is 50 Hz suddenly changed to 51 Hz and continued till 15 sec also in that period,there is 3rd order and 5Th order harmonics exists.At 15 Th sec the fundamental frequency again changed to 50 Hz(also have harmonics of order 3rd and 5th) and this is continued till 20 Th sec .I need to extract the fundamental frequency also the change in the fundamental frequency and i need to plot the change in the frequency from 50 Hz to 51 Hz and back to 50 Hz vs time in a graph, That means, i need to plot it in a graph frequency(y axis) and time(x axis).

I used 1 D discrete(daubechies)(db4)(4 levels)wavelet transform for that.I gained the db1,db2,db3,db4, levels and a1,a2,a3,a4.I used the commands available in wavelet tool box. Now i need to extract the fundamental and change in the frequency of fundamental and i need to plot the change in the fundamental vs time in a graph,means the frequency in y axis and time in x axis how can i do that?

I tried lots of methods, But i am not getting the final graph,can any one help me in this issue?

Expecting the reply.

Answer 1

[Wayne King]

You have not told us what the sampling frequency is of the data, but I doubt you are going to get satisfactory results using the decimated discrete wavelet transform for this.

I think if a wavelet technique is going to work, you are going to have to use the continuous wavelet transform.

[mskumarsajeesh mskumar]

The sampling frequency is 2500 Hz,I need to extract the fundamental frequency and change in the fundamental frequency and i need to plot the graph between the frequency(y axis) vs time(x axis) . i used discrete wavelet transform,daubchies(db4)(level4)using wavelet transform till now i just separated the different components and levels only .Is it a bad way?. I do not know how to proceed from here onwards. Could you help me in this?

[Wayne King]

I don't think you are going to get the frequency and time resolution you need with the discrete wavelet transform, that is why I suggested the CWT. I can help, but I can't do it this instant.

[mskumarsajeesh mskumar]

okie.Thanks for the reply,I am ready to shift to cwt,i am ready to wait.