How to generate a signal with single frequency from a signal with number of frequencies?

Sirs, I have got a signal with 17 frequencies (side by side) i.e frequency 1 is followed by 2 and then 3..... upto 17Hz. I am intended to know how could I calculate a signal with single frequency and equivalent to given signal. Amplitude of all frequencies are same(=2V) Please help.

[Manolis Michailidis]

If i understand corectly maybe you want to know the fundamental frequency? if so plot spectrogram and see if that suits you.