how can I find the delay between two seperate sine waves

[keremcant]

I am pulsing an transducer with an FPGA board and I get both the pulse signal and an echo of it after some time. the pulse I am using is a combination of three sine waves. I want to measure the delay between the pulse itself and the echo. how can I do it? probably I will have to compare the signals, but how?

 

[JoannesPaulus]

What tool are you using?

 

[FvM]

Did you try cross-correlation?

 

[Communications_Engineer]

hmm...

cross correlation would be a good approach but correlating sine waves, might not be the best thing as you'll get multiple-peaks.

But I think it will give a decent enough approximate.


Why don't you sent a pn sequence?

 

[FvM]

Why don't you sent a pn sequence?

May be an option, the original poster should clarify the requirements. I was already wondering what's the purpose of a "combination of three sine waves".

I guess it's a small band (e.g. US) transducer, having a sine burst as impulse response anyway. And the intention is to achieve a time resolution of a fraction of the self resonance period. Ambiguousity is then a general problem, not only specific to cross-correlation. The stimulation must be carefully designed, e.g. a phase-keyed or small-band chirp signal. Possibly the threefold sine has a similar purpose.